Ndt Handbook

'v

Non-Destructive Testing Inspector's Handbook

Visual Inspection (VT) Liquid Penetrant Inspection (PT) Magnetic Particle Testing (MT) Ultrasonic Testing (UT) Eddy Current Testing (ET) Radiographic Inspection (RT)

Preface This reference book was designed for use in the field and to support onthe-job training. It should not be Lised as a standard or referred to as a stand-alone document. This book covers basic formulas, charts, and other NDT related information.

Dedication To all the people who have influenced my naval career and where I am today in the NonDestructive field. Thank you. I originally started this project as a self-knowledge application and began receiving comments from my fellow colleagues requesting a copy. I soon realized that this would prove to be an invaluable tool for general infomation in our field. I have received support from both military and civilian personnel and have taken a sample of their suggestions and compiled them for you, the end user. I wanted to take personal credit for this project and realized it would not benefit the NDT field as a whole. Instead, I encourage you, the end user, to change, manipulate, or configure this book for yourself. In closing, "Share the Wealth with Others."

Last Revision Date 20 April 2002

Contact Information [email protected] ndthandbook.zapto.org

Disclaimer This book is not intended for sale or any monetary benefit to the editor.

Inspector's Handbook

Table of Contents

Scope of Standards..............................................................................................................................................iv. .

Chapter 1 - General Information .................................................................I

d

Schedule Designations of Pipe Sizes .............................................................................................................. Copper Tubing Wall Thickness.....................................................................................................................1.1 Decimal to Inches .......................................................................................................................................... 1.1 Temperature Conversions ............................................................................................................................-1.1 Fraction to Decimal Equivalent ..................................................................................................................1-2 Decimal to Second Conversion..................................................................................................................... 1-2 Numerical Place Value Chart ......................................................................................................................1 - 2 Elements of a Nondestructive Examination Symbol.................................................................................... 1-3 Elements of a Welding SyrnboL....................................................................................................................1-3 Examples of Grooves ....................................................................................................................................1-4 Basic Joints (Welding) ..................................................................................................................................1-4 Order of Performing Arithmetic Operations .................................................................................................1-5 Ratio And Proportion.................................................................................................................................... 1-6 Calculation of Area .................................................................................................................................... 1-7 Weld Area Calculation.................................................................................................................................. 1-7 Common Symbols and Terms ....................................................................................................................... 1-7 Solution of Right-angled Triangles ............................................................................................................... 1-9 1 10 ................................................................................................................... . Basic Illustration of a Weld Welding Processes....................................................................................................................................... - 11 Backing Ring Common Defect Locations .................................................................................................. 1.12 Consumable Insert Common Defect Locations .......................................................................................... 1.12 Primary Processing Discontinuities ............................................................................................................ 4 Finish Processing Discontinuities ................................................................................................................ Dial Indicating Calipers ..............................................................................................................................1- 15 Micrometer ............................................................................................................................................... 1 15 1 - 16 Thread Terminology (fasteners) ................................................................................................................. Tap and Drill Size Chart:.............................................................................................................................1-16 Julian Date Calendar (Perpetual)................................................................................................................. 1- 17 Julian Date Calendar p a p Year) .............................................................................................................. -1-18

-

Chapter 2 .Visual Inspection ...................................................................... 2-1 Common Definitions and Examples ...........................................................................................................2 - 1 Chapter 3 .Liquid Penetrant Testing ..........................................................3-1 Common Terms and Definitions ..................................................................................................................-3-1 Prorated Maximum Number of Indications ..................................................................................................3-6 Areas of Circles .............................................................................................................................................3-6 Penetrant Wetting Characteristics .................................................................................................................3-7

Chapter 4 .Magnetic Particle Testing......................................................... 4-1

Common Definitions and Examples .............................................................................................................4. 1 Longitudinal Magnetization Math Formula ..................................................................................................4F7 Prorated Maximum Number of Indications .................................................................................................. Areas of Circles ............................................................................................................................................. Common Types of Magnetization ................................................................................................................4-9 Inspector's H m m k

-

4

Theory: "RigheHand Rule .......................................................................................................................... -4-9

Hysteresis=Curve........................................................................................................................................ -4-10 4- 11 Magnetic Particle Field Indicator (Pie Gage) .............................................................................................. *&

....................................................................5- 1 Chapter 5 .Ultrasonic Testing Common Terms and Definitions ................................................................................................................... 5-1 ............................................................................................................................ Common Math Formulas 5- 12 Calibration Chart . UT Shearwave .............................................................................................................5- 13 FPADSCRhD .............................................................................................................................................. 5- 14 ............................................................................................................................................. Velocity Chart 5- 15 Chapter 6 .Eddy Current Testing ...............................................................6-1 Common Terms and Definitions ................................................................................................................... - 1 Two Types of Electrical Current ...................................................................................................................6-6 Conductivity and the IACS ...........................................................................................................................6-7 Right Hand Rule ............................................................................................................................................ 6-7 Magnetic Domains ........................................................................................................................................6-9 Depth of Penetration................................................................................................................................... 6-12 Limitations of Eddy Current Testing .........................................................................................................6-18 Advantages of Eddy Current Testing ...................................................................................................... 6 18 Summary of Properties of Eddy Currents ................................................................................................... 6-18 Eddy Current Relationship of Properties ............................................................................................ 6 - 18

Chapter 7 .Radiographic Inspection ...........................................................7-1 Common Definitions and Examples ............................................................................................................ -7-1 Structure of the Atom and an Element .......................................................................................................... 7-8 Components of an Isotope............................................................................................................................. 7-8 Characteristics of A Radioactive Element .................................................................................................... 7-8 Two Types of Radiation................................................................................................................................ 7-8 History of Radiography................................................................................................................................. 7-9 60' Coverage for Pipes and Location Marker Measurements ....................................................................7-11 Common Math Formulas ....................................................................................................................... 7 12 Magic Circles ....................................................................................................................................... 7 1 5 Single Wall Exposure I Single Wall Viewing for Plate ........................................................................... 7-15 Single Wall Exposure 1 Single Wall Viewing for Pipe .............................................................................7-16 Double Wall Exposure 1 Double Wall View (superimposed)...................................................................7-16 Double Wall Exposure I Double Wall View (offset) .............................................................................7-17 Double Wall Exposure 1 Single Wall View ...............................................................................................7-17 KILLER CARL ...........................................................................................................................................7-18

Penetrameter Material and Group Numbers ..............................................................................................7-18 Penny T-Hole Maximum Density..................................................................................................... 7 19 2% Penetrameter Quality Conversion Chart (X-RAY ONLY)................................................................... 7-20 Basic Components of an X-ray Tube ..........................................................................................................7-25 Types of Scatter Radiation .......................................................................................................................... 7-25 . . Radiographc Fllm Interpretation................................................................................................................7-25 . . Radiographic Film Interpretation................................................................................................................7-26 Probable Causes and Corrective Action for Automatic Film Processing ...................................................7-50 Probable Causes and Corrective Action for Processed Radiographic Film ................................................7-51 Inspector's Handbook

iii

Scope of Standards

.

NSTP 271 REQUIREMENTS FOR NONDESTRUCTIVE TESTING METHODS This document covers the requirements for conducting nondestructive tests (NDT) used in detenninin( presence of surface and internal discontinuities in metals. It also contains the -mum requirements necessary qualifL nondestructive test and inspection personnel, procedures, and nondestructive equipment. This document does not contain acceptance criteria for nondestructive test. This document does not cover all of the requirements for performing nondestructive tests in an underwater environment. Nondestructive tests in an underwater environment shall be performed as specified in NAVSEA S0600-AA-PRO-070.

.

NSTP 248 REQUIREMENTS FOR WELDING AND BRAZING PROCEDURE AND PERFORMANCE QUALIFICATION This document contains the requirements for the qualification of welding and brazing procedures, welders, welding operators, brazers and brazing operators that must be met prior to any production fabrication. It includes manual, semiautomatic, automatic and machine welding and brazing of ferrous, nonferrous, and dissimilar metals. The qualification tests required by this document are devised to demonstrate the adequacy of the welding or brazing procedures and to demonstrate the ability of welders, brazers, welding operators and brazing operators to produce sound welds or brazes. NSTP 278 REQUIREMENTS FOR FABRICATION WELDING AND INSPECTION, AND CASTING INSPECTION AND REPAIR FOR MACHINERY, PIPING, AND PRESSURE VESSELS This document contains the welding and allied processes (except brazing) and casting requirements including inspection for the fabrication, alteration, or repair of any item or component of machinery, piping, and pressure vessels in ships of the United States Navy. MILSTD 2035 NONDESTRUCTIVE TESTING ACCEPTANCE CRITERIA The acceptance criteria contained herein are for use in determining the acceptability of nondestructive t. (NDT)discontinuities in castings, welds, forgings, extrusions, cladding, and other products when specified by the applicable Naval Sea Systems Command (NAVSEA) drawing, specification, contract, order, or directive.

-

NSTP 1688 FABRICATION, WELDING AND INSPECTION SUBMARINE APPLICATIONS This document contains minimum requirements for fabrication and inspection of submarine and non combatant submersible structures, including shipbuilding practices, specifications for materials, weld joint design, workmanship, welding, inspection, and record requirements. MILSTD 1689 FABRICATION, WELDING, AND INSPECTION OF SHIPS STRUCTURE This standard contains the minimum requiremeas for the fabrication and inspection of the hull and associated structures of combatant surface ships. The requirements for shipbuilding, materials, welding, welding design, mechanical fasteners, workmanship, inspection, forming, castings and records are included. It also applies to those submarine structures which are not high-yield strength steels. MILSTD 22D WELDED JOINT DESIGN This standard covers welded joint designs for manual, semiautomatic, and automatic arc and gas welding processes for use onmetals and weldments, as applicable, when invoked by a fabrication document. The welded joint designs shown herein represent standard joint designs used in welded fabrication and are not intended to be all inclusive.


NSTP CHAPTER 074 - VOLUME 1WELDING AND ALLIED PROCESSES This chapter furnishes both the minimum mandatory requirements (indicated by the word shall) and guidance information (indicated by the words should or may) necessary for welding, brazing, inspection, and safety when used for ship maintenance, repair, and alteration. -NSTP CHAPTER 074 - VOLUME 2 NONDESTRUCTIVE TESTING OF METALS QUALIFICATION AND CERTIFICATION REQUIREMENTS FOR NAVAL PERSONNEL (NON-NUCLEAR) This chapter is M s h e d to ensure achievement of uniform and reliable nondestructive tests on naval materials and components, implementation of the training, qualification, and certification programs described in this chapter should be followed precisely.


Copper Tubing Wall Thickness Decimal to Inches

inches 1 12 = decimal decimal 12 = inches

Temperature Conversions -

Fahrenheit = (915 * C) + 32 Celsius = (F - 32) * 519


1

Fraction to Decimal Eauivalent

I

Decimal to Second Conversion

I

PLACE)

Numerical Place Value Chart

I

ForExample2,262.357.619844 2

MILLIONS

1,000,000 D 6

THOUSANDS TEN THOUSANDS 2 THOUSANDS

3

HUNDREDS

5

TENS

bI

UNITS

HUNDREDTHS

1/100

0.01

111,000

0.001

1110,000

0.0001

1H00.000

0.00001

E

10,000

C 9 THOUSANDTHS

1,000

1 8

loo 10

I

1/10

100,MK)

1

1

A4

ILI

I

TENTHS

TEN THOUSANDTHS HUNDRED TEN THOUSANDTHS MILLIONTHS

I

0.1

111,000,000 0.000001

I

I

Elements of a Nondestructive Examination Symbol LENGTH OF SECTION TO BE EXAMINED

NUMBER OF EXAMINATIONS REFERENCE LINE

-EXAMINE SPECIFICATION OR OTHER REFERENCE

IN FIELD

EXAMINE-ALL-AROUND

TAIL

ARROW RADIATION DIRECTION

FIELD EXAMINATION

EXAMINE ALL AROUND

/

L

Elements of a Welding Symbol GROOVE ANGLE: INCLUDED ANGLE OF COUNTERSINK FOR PLUG WELDS ROOT 0PENING:DEPTH OF FILLING FOR PLUG AND SLOT WELDS LENGTH OF WELD PITCH OF WELDS -FIELD WELD

FINISH SYMBOL GROOVE WELD SIZE DEPTH OF BEVEL; SIZE OR STRENGTH FOR CERTAIN WELDS SPECIFICATION OR OTHER REFERENCE (OMITTED WHEN NOT USED)

T

WELD-ALL-AROUND

TAIL

ARROW NUMBER OF SPOT, SEAM, STUD, PLUG. OR PROJECTION WELDS

A

GROOVE Square

V

Scad

U

Mvel

-v-- --LL-- -- . - --Y-- -A- --1'T-- -A-- --Y---Ki

7r

Fillet

Plug or Slot

Stud

Spot or Projetiin

Seam

Back or Backing

Flarebevel

Flare-V

J

-I/_---LC-2x --

--rcFlange

Surfacrng

Edge

1

Corner

Basic Weld Symbols

Weld all around

Field Weld

Melt ~hrough

Consumable Insen (Square)

Backing or Spacer (Recrangle)

/-i


,Contour Flush or Flat

Convex

Concave

-Tee

Examples of Grooves

Single J

square

Single Vee

Single Bevel

Double Bevel

Single U

Basic Joints (Welding)

I

I

' /I

corner

w e

Lav

/ /

Tee


Order of Performing Arithmetic Operations When several numbers or quantities in a formula are connected by signs indicating that additions, subtractions, multiplications, or divisions are to be made, the multiplications and divisions should be carried out %st, in the order in which they appear, before the additions or subtractions are performed. 1 , Examples:

10+26X7-2=10+182-2=190 18+6+15X3=3+45=48 12+14+2-4=12+7-4=15

When it is required that certain additions and subtractions should precede multiplication's and divisions, use is made of parentheses 0 and brackets These indicate that the calculation inside the parentheses or brackets should be carried out complete by itself before the remaining calculations are commenced. If one bracket is placed inside of another, the one inside is first calculated.

n.

Examples:

(6-2)X5+8=4X5+8=20+8=28 6 X ( 4 + 7 ) + 2 2 = 6 X 11 - 2 2 = 6 6 + 2 2 = 3 2+[1OX6(8+2)-4]X2=2+[1OX6Xl0-4]X2 =2+[600-4]X2=2+596X2=2+1192=1194

The parentheses are considered as a sign of multiplication; for example, 6(8 + 2) = 6 x (8 + 2). The line or bar between the numerator and denominator in a fractional expression is to be considered as a division sign. For Example,

In formulas the multiplicationsign (X) is often left out between symbols or letters, the values of which are to be multiplied. Thus

ABC AB=AXB,and-=

(AXBXC)+D D


Ratio And Proportion The ratio between two quantities is the quotient obtained by dividing the first quantity by the second. For example, the ration between 3 and 12 is '14, and the ratio between 12 and 3 is 4. Ratio is generally indicated P - * d sign (:); thus 12 : 3 indicates the ratio of 12 to 3.

A reciprocal or inverse ratio is the reciprocal or the original ratio. Thus, the inverse ratio 5 : 7 is 7 : 5. In a compound ratio each term is the product of the corresponding terms in two or more simple ratios. Thus when

then the compound ratio is:

Prop is the equality of ratios. Thus,

The first and last tenns in a proportion are called the extremes; the second and thirds, the means. The product of the extremes is equal to the product of the means. Thus,

If third terms in the proportion are known, the remaining term may be found by the following rules: 1) The first term is equal to the product of the second and third terms, divided by the fourth term.

2) The second term is equal to the product of the first and fourth terms, divided by the third.

3) The third term is equal to the product of the first and fourth terms, divided by the second.

4) The fourth term is equal to the product of the second and third tenns, divided by the first.


Calculation of Area

Square/Rectangle

=

Circles

-

Triangle

=

Sphere

-

Length

* Width

w2

Height * Base

*

1/2

4m2

Weld Area Calculation

* Width

Structural Welds

=

Length

Piping Welds

=

Circumference (OD*7t) * Width

Socket Welds

(measured)

= L x W L = ((OD at A + OD at B) / 2) *7t W = Width of the weld is measured.

Common Symbols and Terms 3.1415

Diameter / 2 Inside Diameter Outside Diameter Less Than

(ie 6 ~ 9 )

Greater Than

(ie 9>6)

Equal To or Less Than Equal To or Greater Than Plus or Minus InspectaPs Handbook

.

Change percent ( % ) to decimal (0.0) Move decimal point 2 spaces to the left and drop the percent sign., Example: 2% = 2.0% = -02 Change decimal (0.0) to percent ( % ) . .. Move decimal point 2 units to the right and add the percent sign. Example: .43 = 43% Change a fraction to a decimal. Divide the numerator by the denominator. Example: 1/2 = 1 divided by 2 = .5 Tm = Material Thickness, thickness of the thinner member excluding reinforcements. Ts = Specimen Thickness, thickness of the thinner member including reinforcements. Minimum Weld Throat Thickness Based upon 1T X 1T

= .7

x Tm


d

Solution of Right-angled Triangles

Basic Illustration of a Weld

FILLET LEG SIZE OF WEW

1qxctoP"sHandbook

Welding Processes

ha

ELECTRODE COVERING

Shielded Metal Arc Welding (SMAW) An arc welding process, which melts and b,ins metals by heating them with an arc oetween a covered metal electrode and the work. Shielding gas is obtained from the electrode outer coating, often called flux. Commonly referred to as "stick" welding.

METAL AND SLAG SOLIDIFIEL) SLAG

SHELDINGGASIN

ON WELD

CURRENT CONDUCTOR

WIRE GUIDE

DIRECTION OF WELDING

AND CONTACT

GAS NOZZLE

Gas Metal Arc Welding (GMAW) An arc welding process, which joins metals by heating them with an arc. The arc is between a continuously-fed filler metal (consumable) electrode and the m r k piece. Shielding gas is supplied from an external source of inert gas, normally argon, helium, or a mixture of the two. Commonly referred to as "MIG" welding.

WIRE GUIDE 6. CONTACT TUBE

joins metals by heating them with an arc between a continuous, consumable electrode wire and the work Shielding is obtained from a flux contained within the electrode core. Depending upon the type of flux-cored wire, added shielding may or may not be provided from externally supplied gas or gas mixture.

tungsten electrode, which should not become part of the *ompletedweld. Filler metal is normally used when welding. L Jsually helium or argon, or mixture, is used for shielding gas. Inspector's Handbook

1-1 1

Backing Ring Common Defect Locations

OVERLAP UNDERCUT

\

CRACKING SLAG/OXIDE INCLUSIONS TUNGSTEN INCLUSIONS POROSITY

I

i

INCOMPLETE (LACK OF) FUSION CRACKING

BAD FITUP SLAG BETWEEN BACKING RING AND PIPE ID

/

INCOMPLETE (LACK OF) PENETRATION SLAG OR UNDERCUT AT THE ROOT TOES CRACKING

u

u

MELT-THROUGH BURN-THROUGH

Consumable Insert Common Defect Locations

OVERLAP UNDERCU

CRACKING SLAG/OXIDE INCLUSIONS POROSITY

INcLuSroNS

I

INCOMPLETE (LACK OF) FUSION CRACKING

CONCAVITY MELT-THROUGH BURN-THROUGH INCOMPLETE (LACK OF) FUSION UNDERBEAD CRATERS CENTERLINE CREASE OVERLAP CRACKING UNDERCUT AT THE#OO&OTTO# BACKING GAS LOS A% MPLETE (LACK OF) PENETMTION

4

Discontinuity

Process

Cold Shut

:L

Primary Processing Discontinuities Caused By Lack of h i o n between two intercepting surfaces of metal as it flows into the cast

Hot Tear

I

Difference in cooling rates between thin sections and thick sections

Improperly designed mold causing premature blockage at the mold gate

Subsurface

Blow Holes

Inability of external gasses to escape h m the mold

Surface

Porosity

L

I

Lap

Folding of metal in a thin plate on the surface of the forging

Burst

Forging at improper temperature

(bar

Flattening and lengthening of discontinuities in parent material

I

Flattening and lengthening of discontinuities found in parent material Lengthening of surface cracks found in parent

F r I L a C k o f Fusion

I

pipe

I ( I I

Subsurface Subsurface Surface

(

I I

Surface (inner and outer) Subsurface

Inner Surface

Metal buildup on piercing material

I

Sizing mandrel dragging Present in parent material

Porosity

( Present in parent material

Galling (cracks)

w

Surface or Subsurface

Present in the parent material (round bar stock)

Seams

I I

I

Slugs Gouges

1-

Incomplete weld

Surface

Present in the parent material (sheet or parent material)

Laminations

Seams

I

Entrapped internal gasses

Laminations (flat plate) sdgem

Seamless Pipes and Tubes ,

surface

Microshrinkage

Forging

I

1

Subsurface

Casting

I

Surface

Lack of enough molten metal to fill the space created by shrinkage

Cavity

I

Location

Improper metal flow through the die

(

Surface

1

Surface

1


1- 13

I

Process

Discontinuity

Grinding

Cracks

Finish Processing Discontinuities Caused By Excess localized heat created between the grinding wheel and the material

Location Surface ~

Stress built up by improper processing - unequal heating and cooling

Heat Treating

Stress Cracks

Explosive Forming

Cracks and Tears Crater Cracks (star, transverse, and longitudinal)

-

Extreme deformation overstresses the material

I

surface

I

Improper use of heat source

I


I

-

Porosity Slag Inclusions Welding

Incomplete cleaning of slag fiom the weld between passes

I

I

Machining

I

I

Subsurface

I

Lack of Penetration

Improper welding technique

I


I

Lack of Fusion


Undercut


Tears

Pz?," I

1 Electroplating I


Excessive current used during GTAW

Cracks

1


Tungsten Inclusions

Weld overlaps parent material - not b e d

Overlapping

Bending

Surface

I

Entrapped gasses

I

I

Surface

Stresses built up by the weld contraction (if material is restrained)

Stress Cracks

.-/

-

I

I

-

Subsurface

1

I

surface

(

I

surface

I

1

Surface

I

-

Overstress of material Working with dull tools or cutting too deep

Cracks

Relief of internal stress

Surface

Cracks

Relief of internal stress

Surface

Inspector's Harrdbook

Dial Indicating Calipers

1. VerifL the caliper's calibration date is current, and clean all dirt fiom measuring faces. Perform user calibration on dial indicator, ensure reading is zero, and tighten the bezel clamp as needed. 2. Adjust measuring faces, contact points, to fit item being measured.

3. Apply f m pressure to fine adjusting roll and ensure measuring contacts are in contact with the material being measured. 4. Apply lock screw and read measurement in place if practical. If not, remove calipers carefully to prevent false measurements. Micrometer PART TO BE MEASURED

GRADUATIONS TO BE READ

READING L I N E

FRAME

1. Verifj. that the micrometer's calibration date is current, and clean all dirt from measuring contacts.

C

VEPN~ER .000/ GIRHRT/ONS

IS

2. Attach ball if measuring curved surfaces. 3. Adjust micrometer to fit the item being measured, do not spin frame to adjust the micrometer.

-

s-L f CYrC too 4%vo. Olb GRRDVRT/O/YS

4. Slip the micrometer over the area to be measured by placing the anvil f d y against the material and slowly turn the thimble clockwise until spindle is firmly against the material. Then turn the ratchet three clicks to be sure equal pressure is applied. w

5. Take reading in place, or set the locking nut and remove fiom the item. Determine reading on scale and note accordingly. Do not forget to minus the ball measurement if used.


AXIS

CREST

PITCH DIAMETER

R m

Tap and Drill Size Chart

7

1

THREAD SIZE


Julian Date Calendar (Perpetual)

Day Jan Feb 1 0 0 1 032 "w 2 002 033 3 003 034 004 035 4 5 005 036 6 006 037 007 038 7 8 008 039 9 009 040 10 010 041 11 011 042 12 012 043 13 013 044 14 014 045 15 015 046 16 016 047 17 017 048 18 018 049 19 019 050 20 020 051 21 021 052 22 022 053 23 023 054 24 024 055 25 025 056 26 026 057 27 027 058 28 028 059 29 029 30 030 . 31 031

L'

Mar 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090

Apr 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 I13 114 115 116 117 118 119 120

May 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151

June 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181

July Aug 182 213 183 214 184 215 185 216 186 217 187 218 188 219 189 220 190 221 191 222 192 223 193 224 194 225 195 226 196 227 197 228 198 229 199 230 200 231 201 232 202 233 203 234 204 235 205 236 206 237 207 238 208 239 209 240 210 241 211 242 212 243

Sep 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273

Oct 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 -

Nov 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334

-

Dec 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365

Day I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

L


1-17

i

Julian Date Calendar (Leap Year)

Day 1 2 3 4 5 6 7 8 9 I0 I1 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1-18

Jan 001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031

Feb 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060

Mar 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091

Apr 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121

May 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152

June 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182

July 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213

Aug 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244


Sep Oct 245 275 246 276 247 277 248 278 249 279 250 280 251 281 252 282 253 283 254 284 255 285 256 2 8 6 257 287 258 288 259 289 260 290 261 291 262 292 263 293 264 294 265 295 266 296 267 297 268 298 269 299 270 300 271 301 272 302 273 303 274 304 305

Nov 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335

Dec 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366

C 1 2 3 4 5 6 7 8 9 I0 I1 12 13 14 15

*

'

v l b ,

17 18 19 20 21 22 23 24 25 26 27 28 29

30 3. 4

Chapter 2 - Visual Inspection Common Definitions and Examples Aligned rounded indications Four or more indications in a line, where each is separated i/ from the adjacent indication by less then 1/16 inch or D, whichever is greater, where D is the major diameter of the larger of the adjacent indication.

r

Arc strike

Any localized heat-effected zone or change in the contour of the surface of the finished weld or adjacent base metal resulting from m atc or heat generated by the passage of electrical energy between the surface of the finished weld or base metal and a current source, such as welding electrodes or magnetic particle inspection prods. Burn throu~h

A void or open hole that extends through a backing ring, strip, fused root, or adjacent base metal.

Burst A rupture caused by forging at improper temperatures. Bursts may be either internal or external to the surface. Cold shut The result of pouring metal over solidified metal. /

+ Track orAtear linear rupture of metal under stress. Crater pit An approximately circular surface condition exceeding into the weld in an irregular manner caused by insufficient filler metal at the weld stop. Defect One or more flaws whose aggregate; size, shape, orientation, location, or properties do not meet the specified acceptance criteria and are rejectable. Discontinuity Any interruption in the normal physical structure or configuration of a part, which will cause a detectable indication or signal when nondestmctively examined. Evaluation A review, following interpretation of the indications noted, to determine whether they meet specified cceptance criteria. L


2-1

False indication An indication that is interpreted to be caused by a condition other than a discontinuity or imperfection. Heat checks Fissures or tears in the weld heat affected zone of material containing low melting point.

ure of quality characteristic from its intended condition. IndicaticLn IZvidence of a discontinuity that requires interpretation to determine its significance. ete fusion ,ack of complete fusion of some portion of the metal in a Weld jolnt with adjacent metal. The adjacent metal may be either base metal or previously deposited weld metal, or consumable insert.

I

Incomplete penetration Lack of penetration of the weld through the thickness of the joint, or penetration which is less than specified. Interpretation The determination of whether indications are relevant, nonrelevant, or false.

Lap (forginas) Folding of metal on the surface of the forging, usually occ u when some of the forging metal is squeezed out between the two dies. '

Linear indication An indication in whichthe length is equal to or greater than three times the width. Melt through A convex or concave irregularity on the surface of a backing ring or strip, fused root, or adjacent base metal resulting from fusion completely through a localized region but without development of a void or open hole. Non-linear rounded indications Indication whose length is less than three times its width. Nonrelevant indications An indication that is caused by a condition or type of discontinuity that is not relevant.


Oxidation A condition resulting from partial or complete lack of inert gas shielding of a surface which is heated ring welding resulting in formation of oxide on the surface. This condition may range fiom slight oxidation idenced by a multicolored or tightly adhering black film to the extreme of a very rough surface having a crystalline appearance. Porosity Gas pockets or voids in weld metal or castings. Quench crack A crack formed as a result of the& rapid cooling fiom a high temperature.

stresses produced by

Root surface concavity A depression on the root surface of a weld which may be due to gravity, internal purge, or shrinkage. Root surface centerline crease or shrinkage An intermittent or continuous peripheral centerline concavity formed on the root surface. Root undercut A groove in the internal surface of a base metal or backing ring or strip along the edge of the root of the weld. Shrinkage Void, or voids, that may occur in molten metal due to contraction during solidification.

& s Non-metallic solid material entrapped in the weld metal, between weld metal and base metal, or in a casting. Tungsten inclusion Tungsten entrapped in the weld deposit. Undercut A groove melted into the base metal at the toe of the weld and left unfilled by weld metal. Unfused chaplet A metal support used in the casting process, which has not fused with casting material.

Weld spatter Metal particles which deposit on the surface of the weld or adjacent base metal during welding and which do not form a part of the weld.



Chapter 3 - Liquid Penetrant Testing Common Terms and Definitions Alkaline Any soluble mineral salt or mixtures of salt capable of neutralizing acids.

L

Angstrom Unit (A) A unit of length equal to lo8 cm and used to express wavelengths of light; i.e., electromagnetic radiation. Background The surface upon which an indication is viewed. It may be the natural surface of the test article or it may be the developer coating on the surface. This background may contain traces of unremoved penetrant (fluorescent or visible), which, if present, can interfere with the visibility of indications. Background Fluorescence Fluorescent residues observed over the general surface of the test article during fluorescent penetrant E h Term used colloquially to designate the liquid penetrant inspection materials into which test articles are immersed during inspection process. Black L i ~ h t Light radiation in the near ultraviolet range of wavelengths (3200 to 4000 A), just shorter than visible light. Black Light Filter A filter that transmits black light while suppressing visible light and hard ultraviolet radiation with L wavelengths less than 3200 angstroms. Bleedout The action of the entrapped Penetrant in spreading out from surface discontinuities to form an indication. Blotting The action of the developer in soaking up the entrapped penetrant from d a c e discontinuities to form an indication. Capillary Action or Capillarity The tendency of liquids to penetrate or migrate into small openings such as cracks, pits, or fissures. Carrier Fluid (Vehicle or Medium) A fluid in which liquid penetrant inspection materials are dissolved or suspended. Clean Free from interfering solid or liquid contamination on the d a c e . Comparative Test Block An intentionally cracked metal block having two separate but adjacent areas for the application of different penetrants so that a d
Contact Emulsifier An emulsifier that begins emulsifying penetrant upon simple contact with the penetrant; usually oil-base (Lipophilic). Contrast w The difference in visibility (brightness or coloration) between an indication and the surrounding surface. Dark Adaptation The adjustment of the eyes when one passes from a bright to a darkened area. Detergent Remover A penetrant remover that is a solution of a detergent in water. Also Hydrophilic Emulsifjer. Developer A material that is applied to the test article surface after excess penetrant has been removed and that is designed to enhance the penetrant bleedout to form indications. The developer may be a fine powder, a solution that dries to a fine powder, or a suspension (in solvent, water, alcohol, etc.) that dries leaving an absorptive film on the test surface. Developing Time The elapsed time necessary for the applied developer to bring out indications from penetrant entrapments. Also called Development Time. Dragout

The canput or loss of penetrant materials as a result of their adherence to the articles being processed. Drain Time That portion of the penetrant inspection process during which the excess penetrant, emulsifier, detergent remover, or developer is allowed to drain fiom the test article.

w

Dry Developer A fine, dry powder developer that does not employ a carrier fluid.

Drying Oven An oven used for drying test articles. Drvinn Time A time allotted for a test article to dry.

DuaLresponse Penetrant A penetr- that contains a combination of visible and fluorescent dyes. Dwell Time The total time that the penetrant or emulsifier is in contact with the test surface, including the time required for application and the drain time. Also see Emulsification Time. Electrostatic Spraying A technique of spraying wherein the material being sprayed is given a high electrical charge while the test axticle is grounded. u


Emulsification Time The period of time that an emulsifier is permitted to combine with the penetrant prior to removal. Also called Emulsifier Dwell Time. Tmulsifier A liquid that combines with an oily penetrant to make the penetrant water-washable. Also see Hydmphilic Emulsifier &d Lipophilic Emulsifier.

'v

Flash Point The lowest temperature at whicha volatile, flammable liquid will give off enough vapor to make a combustible explosive mixture in the air space surrounding the liquid surface. Fluorescence The emission of visible radiation by a substance as a result of, and only during, the absorption of black light radiation. Fluorescent Dye Penetrant An inspection penetrant that is characterized by its ability to fluoresce when excited by black light. Halogen (Halonenous) Any of four very active nonmetallic elements; chlorine, iodine, fluorine and bromine.

-

Hydrophilic Emulsifier A water-base agent that, when applied to an oily penetrant, renders the penetrant water-washable. Can be used as a Contact Emulsifier, but more often the emulsifier is added to the water rinse and accompanied by some form of mechanical agitation or scrubbing to remove excess penetrant. Sometimes called a Hydrophilic Scrubber.

~ e a Testing k A technique of liquid penetrant testing in which the penetrant is applied to one side of the surface while the other side is inspected for indications that would indicate a through- leak or void. Lipophilic Emulsifier An oil-base agent that, when applied to an oily penetrant, renders the penetrant water-washable. Usually applied as a Contact Emulsifier. Near Surface Discontinuity A discontinuity not open to, but located near, the surface of a test article.

,Nonaqueous Wet Develowr A developer in which the developing powder is applied as a suspension in a quick-drying solvent. Also called Solvent Developer. Penetrability The property of a penetrant that causes it to find its way into very fine openings, such as cracks. Penetrant A liquid (sometimes gas) capable of entering discontinuities open to the surface, and which is adapted to the inspection process by being made highly visible in small traces. Fluorescent penetrants fluoresce brightly under black light while the visible penetrants are intensely colored to be noticeable under visible light. L


Post-emulsification Penetrant A penetrant that requires the application of a separate emulsifier to render the surface penetrant waterwashable. Also can be removed by applying a solvent remover. Precleaning 4 The removal of surface contaminants or smeared metal from the test article so that they cannot interfere with the penetrant inspection process. Ouenchin~of Fluorescence The extinction of fluorescence by causes other than removal of black light (the exciting radiation). Resolution The property of a test system that enables the separation of indications of close proximity in a test article.. Rinse -

The process of removing liquid penetrant inspection materials from the surface of an article by washing or flooding with another liquid-usually water. Also called Wash. See-ability The characteristic of an indication that enables th: observer to see it against the conditions of background, outside light, etc. Self-developinnPenetrant A penetrant not requiring the use of a developer. Useful for production work in the detection of gross discontinuities. Sensitivity The ability ofthe penetrant process to detect minute surface discontinuities.

.'v

Solvent Removed A penetrant-removal technique wherein the excess penetrant is washed or wiped from the test surface with a solvent remover. Solvent Remover A volatile liquid used to remow excess surface penetrant from the test article. Sometimes called Penetrant Remover. Surface Tension That property of liquids which, due to molecular forces, tends to bring the contained volume into a form having the least superficial area. Viscosity The state or degree of being viscous. The resistance of a fluid to the motion of its particles. Visible Dye Penetrant An inspection penetrant that is characterized by its intense visible color-usually red. Also called Color Contrast or Nonfluorescent Penetrant. Water-soluble Developer A developer in which the developer powder is dissolved in a water carrier to form a solution. Not a suspension. 3-4


d

Water-suspended Particle Developer A developer in which the developer particles are mixed with water to firm a suspension. Water-wash A penetrant-removal technique wherein excess penetrant is washed or flushed from the test surface with water.

L

Water-washable Penetrant A type of penetrant that contains its own emulsifier, making it water-washable. Water Tolerance The amount of water that a penetrant, emulsifier, or wet developer can absorb before its effectiveness is impaired. Wet Developer A developer in which the developer powder is applied as a suspension or solution in a liquid-usually water or alcohol. Wetting Ability The ability of a liquid to spread out spontaneously and adhere to the test article's surfaces.


w

(MAX # OF INDICATIONSl36)X ACTUAL AREA = NEW MAX # OF INDICATIONS

-

I

.I00

Area = m2


.0079

I

Penetrant Wetting Characteristics

Inspector's HandGook

Inspector's Randbook

Chapter 4 - Magnetic Particle Testing Common Definitions and Examples -.&

gap

When a magnetic circuit contains a small gap, which the magnetic flux must cross, the space is referred to as an air gap. Cracks produce small air gaps on the surface of an article. Alternating current Electric current periodically reversing in polarity or direction of flow. AmDere The unit of electrical current. One ampere is the current that flows through a conductor having a resistance of one ohm at a potential of one volt.

Ampere turns The product of the number of turns in a coil and the number of amperes flowing through it. A measure of the magnetizing or demagnetizing strength of the coil. W h The suspension of iron oxide particles in a liquid vehicle (light oil or water). J

Black light Radiant energy in the near ultraviolet range. This light has a wavelength of 3200 to 4000 angstrom units (A), peaking at 3650 A, on the spectrum. This between visible light and ultraviolet light. $lack light filter A filter that transmits black light while surprising the transmission of visible light and harrml ultraviolet radiation. Carbon steel Steel that does not contain significant amounts of alloying elements other than carbon and maganese. Carrier fluid The fluid in which fluorescent and no* fluorescent magnetic particles are suspended to facilitate their application in the wet method. Central conductor An electrical conductor that is passed through the opening in a ring or tube, or any hole in an article, for the purpose of creating a circular field in the ring or tube, or around the hole. Circular field See Field, Circular Magnetic. Circular magnetization A method of inducing a magnetic field in an article so that the magnetic lines of force take the form of concentric rings about the axis of the current. This is accomplished by passing the current directly through the article or through a conductor which passes into or through a hole in the article. The circular method is applicable for t h detection of discontinuities with axes approximately parallel to the axis of current through the article.


Coercive force The reverse magnetizing force necessary to remove residual magnetism in demagnetizing an article. Coil shot A pulse of magnetizing current passed through a coil surrounding an article for the purpose of l o n g i d magnetization.

-

Contact headshot The electrode, faed to the magnetic particle testing unit, through which the magnetizing current is drawn. Contact pads Replaceable metal pads, usually of copper braid, placed on contact heads to give good electrical contact thereby preventing damage to the article under test. 1

Continuous method An inspection method in which ample amounts of magnetic particles are applied, or are p r e s a on the piece, during the time the magnetizing current is applied. Core -

That part of the magnetic circuit that is within the electrical winding.

Curie point The temperature at which ferromagnetic materials can no longer be magnetized by outside forces, and at which they lose their residual magnetism: approximately 1200 to 1600' F (646 to 871° C) for many metals. Current Flow Technique A technique of circular magnetization in which current is passed through an article via prods or contact 4 heads. The current may be alternating, half-wave rectified, rectified alternating, or direct. C m t Induction Technique A technique of magnetization in which a circulating current is induced in a ring-shaped component by a fluctuating magnetic field. Demamethtio n The reduction in the degree of residual magnetism to an acceptable level. Diamagnetic Materials whose atomic structure won't permit any real magnetization. Materials such as bismuth and copper are diamagnetic. Diffused Indications Indications that are not clearly defined, such as indications of subsurface defects. Direct Contact Magnetization A magnetic particle testing technique in which current is passed throdgh the test article. These include headshots and prod shots. Direct Current An electrical current, which flows steadily in one direction

4-2

Inspector's Handboak

Distorted Field A field that does not follow a straight path or have a uniform distribution. This occurs in irregularly shaped objects. b

Dry Medium Magnetic particle inspection in which the particles employed are in the dry powder f o m

Dry Powder Finely divided ferromagnetic particles suitably selected and prepared for magnetic particle inspection. Electromagnet A magnet created by inserting a suitable metal core within or near a magnetizing field formed by passing electric current through a coil of insulated wire. Etching The process of exposing subsurface conditions of metal articles by removal of the outside surface through the use of chemical agents. Due to the action of the chemicals in eating away the surface, various surface or subsurface conditions are exposed or exaggerated and made visible to the eye. Ferromagnetic A term applied to materials that can be magnetized and strongly attracted by a magnetic field. Field, Circular Mametic Generally the magnetic field in and surrounding any electrical conductor or article resulting from a current being passed through the conductor or article or fiom prods. .field, Longitudinal Magnetic A magnetic field wherein the flux lines traverse the component in a direction essentially parallel with the axis of the magnetizing coil or to a line connecting the two poles at the magnetizing yoke. Field, Magnetic The space within and surrounding a magnetized article, or a conductor carrying current in which the magnetic force is present. Field, Magnetic Leakwe The magnetic field that leaves or enters the surface of an article at a magnetic pole. Field. Multidirectional A magnetic field that is the result of two magnetic forces impressed upon the same area of a magnetizable object at the sametime-sometimes called a "vector field." Field, Residual Mametic The field that remains in magnetizable material after the magnetizing force has been removed Flash Magnetization Magnetization by a current flow of very brief duration.

W

Fluorescence The emission of visible radiation by a substance as the result of and only during the absorption of black light radiation. J ,


Fluorescent Magnetic Particle Inspection The magnetic particle inspection process employing a finely divided fluorescent ferromagnetic inspection medium that fluoresces when activated by black light. V

Flux Density The normal magnetic flux per unit area It is designated by the letter "B" and is expressed in telsa (SI units) or gauss (cgs units).

Flux Leakage Magnetic lines of force which leave and enter an article at poles on the surface. Flux Lines Imaginary magnetic lines used as a means of explaining the behavior of magnetic fields. Their conception is based on the pattern of lines produced when iron filings are sprinkled over a piece of paper laid over a permanent magnet. Also called Lines of Force.

Flux Penetration, Magnetic The depth to which a magnetic flux is present in an article. Furring Buildup or bristling of magnetic particles due to excessive magnetization of the article. Gauss The unit of flux density. Numerically, one gauss is one line of flux per square centimeter of area and is designated by the letter "B." Head Shot A short pulse of magnetizing current passed through an article or a central conductor while clamped between the head contacts of a stationary magnetizing unit for the purpose of circularly magnetizing the article.

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w

Heads The clamping contacts on a stationary magnetizing unit. Horseshoe Magnet A bar magnet bent into the shape of a horseshoe so that the two poles are adjacent. Usually the term applies to a permanent magnet. Hysteresis The lagging of the magnetic effect when the magnetic force acting upon a ferromagnetic body is changed; the phenomenon exhibited by a magnetic system wherein its state is influenced by its previous magnetic history. Hysteresis Loop A curve showing the flux density, "B," plotted as a h c t i o n of magnetizing force, "H." As the magnetizing force is increased to the saturation point in the positive, negative, and positive direction sequentially, the curve forms a characteristic S-shaped loop. Intercepts of the loop with the "B" and "H" axes and the points of maximum and minimum magnetizing force define important magnetic characteristics of the material. Inductance The magnetism produced in a ferromagneticbody by some outside magnetizing force. The magnetism is not the result of passing current through the article. 4-4

Inspector's Randbook

w

Leakage Field The magnetic field forced out into the air by the distortion of the field within an article. ',ifit Intensitv The light energy reaching a unit of surface area per of time.

L . ,

Lonnitudinal Magnetization The process of inducing a magnetic field into the article such that the magnetic lines of force extending through the article are approximately parallel to the axis of the magnetizing coil or to a line connecting the two poles when yokes (electromagnets) are used. Magnet, Permanent A highly-retentive metal that has been strongly magnetized; i.e., the alloy Alnico. Mmetic Field Indicator An instrument designed to detect andlor measure the flux density and polarity of magnetic fields. Magnetic Field Strength The measured intensity. of a magnetic field at a point always external to the magnet or conductor; usually expressed in amperes per meter or oersted (Oe). Magnetic Material Those materials that are attracted by magnetism. Magnetic Particles Finely divided ferromagnetic material. i/

Magnetic Particle Inspection A nondestructive inspection method for locating discontinuities in ferromagnetic materials. Magnetic Poles Concentration of flux leakage in areas of discontinuities, shape changes, permeability variations, etc. Magnetic Writing A form of nonrelevant indications caused when the suface of a magnetized part comes in contact with another piece of ferromagnetic material that is magnetized to a different value. Magnetizing Current The flow of either alternating, rectified alternating, or direct current used to induce magnetism into the article being inspected. Magnetizin~Force ,The magnetizing field applied to a ferromagnetic material to induce magnetization. Medium The fluid in which fluorescent and nonfluorescent magnetic particles are suspended to facilitate their application in the wet method. b Jear Surface Discontinuitv

A discontinuity not open to, but located near, the surface of a test article.


Oersted A unit of field strength, which produces magnetic induction and is designated by the letter "H." /

Paramagnetic 4 Materials which are slightly affected by a magnetic field. Examples are chromium, manganese, aluminun, and platinum. A small group of these materials are classified as ferromagnetic. Permeability The ease with which the lines of force are able to pass through an article. Pole -

The area on a magnetized article fiom which the magnetic field is leaving or returning to the article.

Prods Hand-held electrodes attached to cables used to transmit the magnetizing current from the source to the article under inspection. Rectified Alternating Current Alternating current, which has been converted into direct current. Reluctance The resistance of a magnetic material to changes in magnetic field strength. Residual Magnetism The amount of magnetism that a magnetic material retains after the magnetizing force is removed. Also called "residual field" or "remanence."

w

Residual Technique A procedure in which the indicating material is applied after the magnetizing force has been discontinued. Retentivity The ability of a ~mterialto retain a certain portion of residual magnetization. Also known as rernanence. Saturation The point at which increasing the magnetizing force produces no M h e r magnetism in a material. Sensitivity The capacity or degree of responsiveness to magnetic particle inspection. Settling Test A procedure used to determine the concentration of magnetic particles in a medium or vehicle. Skin Effect The description given to alternating current magnetization due to its containment to the surface of a test article. Solenoid (Coil) An electric conductor formed into a coil often wrapped around a central core of highly permeable mate ,

4-6


,

Suspension The correct term applied to the liquid bath in which the ferromagnetic particles used in the wet magnetic particle inspection method &e suspended. >

Lrest Article An article containing known artificial or natural defects used for checking the efficiency of magnetic particle flaw detection processes. Wet Medium An inspection employing ferromagnetic particles suspended in a liquid (oil or water) as a vehicle. Yoke A U-shaped or C-shaped piece of highly permeable magnetic material, either solid or laminated, sometimes with adjustable pole pieces (legs) amund which is wound a coil carrying the magnetizing current. Yoke Magnetization A longitudinalmagnetic field induced in an article or in an area of an article by means of an external electromagnei shaped like a yoke.

Longitudinal Magnetization Math Formula AT =

45,000 (+/- lo?!)

W)

A = ampere T = turns of the coil L = length of the item D = diameter or cross section of the item

The minimum UD ratio is 2 The maximum L used in calculations is 20 inches


4-7

Common Types of Magnetization Horse shoe (longitudinal)

Central Conductor (circular)

Coil Shot (longitudinal)

Yoke (longitudinal)

Discontinuities

Theory: "Right-Hand Rulen

CURRENT

FLOW


Hysteresis Curve

B+ (FLUX DENSITY) 0 - A = Referred to as the virgin curve A = Saturation point B = Residual field 0 - C = Coercive force D = Reverse saturation point E = Reverse residual field 0 - F = Reverse coercive force

L/

H- (MAGNETIZING FORCE OF OPPOSITE POLARITY TO H+)

H= (MAGNETIZING FORCE)

R (FLUXDENSITY OF OPPOSITE POLARITY TO B+)

SLENDER LOOP

WIDE LOOP

HIGH PERMEABILITY LOW PERMEABILITY HIGH RENTENTMTY LOW RENTENTIVITY HIGH COERCIVE FORCE LOW COERCIVE FORCE LOW RELUCTANCE HIGH RELUCTANCE HIGH RESIDUAL WU3FETISM LOW RESIDUAL MAGNETISM Inspector's Hadbook

d

Magnetic Particle Field Indicator (Pie Gage) Eight low carbon steel pie sections, furnace brazed

Artificial flaw (all segment interfaces)

1 in.

,'

I I I

' '

Nonferrous handle of any Convenient length

/J Copper plate 0.010 in t 0.001 in thick

I

7

\

\

Braze weld or mechanically attach nonferrous trunnions


Inspector's Hanetbook

Chapter 5 - Ultrasonic Testing Common Terms and Definitions -\-scan

Display A dimlav in which the received signal is displayed as a vertical displacement fiom the horizontal sweep

time trace, wkl; the horizontal distance between a& G o signals represents the sound path distance (or time of travel) between the two. Absorption Coefficient, Linear The fractional decrease in transmitted intensity per unit of absorber thickness. It is usually designated by the symbol and expressed in units of cml. Acceptance Standard A control specimen containing natural or artificial discontinuities that are well defined and, in size or extent, similar to the maximum acceptable in the product. Also may refer to the document defining acceptable discontinuity size limits. Acoustic Impedance The factor which controls the propagation of an ultrasonic wave at a boundary interface. It is the product of the material density and the acoustic wave velocity within that material. Amplifier A device to increase or amplify electrical impulses. Amplitude. Indication The vertkal height of a received indication, measured fiom base-to-peak or peak-to-peak.

b.

Angle Beam Testing A testing method in which trammission is at an angle to the sound entry surface. Amle of Incidence The angle between the incident (transmitted) beam and a normal to the boundary interface.

.

Angle of Reflection The angle between the reflected beam and a normal to the boundary interface. The angle of reflection is equal to the angle of incidence. Angle of Refraction The angle between the refracted rays of an ultrasonic beam and the normal (or perpendicular line) to the rehcting surface. Angle Transducer A transducer that transmits or receives the acoustic energy at an acute angle to the surface to achieve a specific effect such up the setting up of shear or surface waves in the part being inspected. Anisotropic A condition in which properties of a medium (velocity, for example) vary according to the direction in vhich they are measured.

, ,


Array Transducer A transducer made up of several piezoelectric elements individually connected so that the signals they transmit or receive nay be treated separately or combined as desired. \

s-,

Attenuation Coefficient A factor which is determined by the degree of scatter or absorption of ultrasound energy per unit distance traveled. Attenuator A device for measuring attenuation, usually calibrated in decibels (dB). B-scan Display A cathode-ray tube display in which the received signal is displayed as an illuminated spot. The face of the CRT represents the area of a vertical plane through the material. The display shows the location of a discontinuity, as it would appear in a vertical section view through the thickness direction of the material. . Back Reflection The signal received from the back surface of a test object.

Back Scatter Scattered signals that are directed back to the transmitterlreceiver. Background Noise Extraneous signals caused by signal sources within the ultrasonic testing system, including the material in test.

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w

Barium Titanate (Polycrystalliie Barium Titanate B a r n 3 ) A ceramic transducer material composed of many individual crystals fired together and polarized by the application of a dc field. Baseline The horizontal line across the bottom of the CRT created by the sweep circuit. Basic.Calibration The procedure of standardizing an instrument using calibration reflectors described in an application . document. Bi-modal The propagation of sound in a test article where at least a shear wave and a longitudinal wave exists. The operation of angle beam testing at less than first critical angle. Boundary Indication A reflection of an ultrasonic beam from an interface. Broad Banded Having a relatively wide frequency bandwidth. Used to describe pulses which display a wide frequency spectnun and receivers capable of amplifying them. 4


C-scan A data presentation method yielding a plan (top) view through the scanned surface of the part. Through gating, only indications arising from the interior of the test object are indicated.

",libration To determine or mark the graduations of the ultrasonic system's display relative to a known standard or reference.

X/

Calibration Reflector A reflector with a known dimensioned surface established to provide an accurately reproducible reference. Collimator

An attachment designed to reduce the ultrasonic beam spread. Compensator An electrical matching network to compensate for circuit impedance differences. Compressional Wave A wave in which the particle motion or vibration is in the same direction as the propagated wave (longitudinal wave). Contact Testing A technique of testing in which the transducer contacts the test surface, either directly or through a thin layer of couplant.

L.

Contact Transducer A transducer which is coupled to a test surface either directly or through a thin film of couplant. Continuous Wave A wave that continues without interruption. Contracted Sweep A contraction of the horizontal sweep on the viewing screen of the ultrasonic instrument. Contraction of this sweep pennits viewing reflections occurring over a greater sound-path distance or duration of time. Comer Effect The strong reflection obtained when an ultrasonic beam is directed toward the inner section of two or three mutually perpendicular surfaces. Couplant A substance used between the face of the transducer and test surface to permit or improve transmission of ultrasonic energy across this b o u n w or interface. Primarily used to remove the air in the interface. Critical An~le The incident angle of the sound beam beyond which a specific refracted mode of vibration no longer exists. Cross Talk An unwanted condition in which acoustic energy is coupled from the transmitting crystal to the receiving .,pystalwithout propagating along the intended path through the material.

Ld


Damping (transducer) Limiting the duration of vibration in the search unit by either electrical or mechanical means.

Dead Zone The distance in a material from the sound entry surface to the nearest inspectable sound path.

\

4

Decibel (dB) The logarithmic expression of a ratio of two amplitudes or intensities of acoustic energy Delamination A laminar discontinuity, generally an area of unbonded materials. Delay Line A material (liquid or solid) placed in front of a transducer to use a time delay between the initial pulse and the fiont surface reflection. Delayed Sweee A means of delaying the start of horizontal sweep, hereby eliminating the presentation of early response data.

Delta Effect Acoustic energy re-radiated by a discontinuity. Detectability The ability of the ultrasonic system to locate a discontinuity. Difiction The deflection, or "bending," of a wave front when passing the edge or edges of a discontinuity. Diffise Reflection Scattered, incoherent reflections caused by rough surfaces or associate interface reflection of ultrasonic waves from irregularities of the same order of magnitude or greater than the wavelength. Discontinuity An interruption or change in the physical structure or characteristics of a material. Dispersion, Sound Scattering of an ultrasonicbeam as a result of diffuse reflection from a highly- irregular surface. Distance Amplitude CorrectionP A C ) Compensation of gain as a function of time for difference in amplitude of reflections fiom equal reflectors at different sound travel distances. Also referred to as time corrected gain (TCG),time variable gain (TVG) and sensitivity time control (STC). Divergence Spreading of ultrasonic waves after leaving search unit, and is a function of diameter and frequency. Dual-Element Technique The technique of ultrasonic testing using two transducers with one acting as the transmitter and one as f receiver. 5-4


.&

Dual-Element Transducer A single transducer housing containing two piezoelectric elements, one for transmitting and one for receiving. zffective Penetration The maximum depth in a material at which the ultrasonic transmission is sufficient for proper detection of discontinuities. Electrical Noise Extraneous signals caused by externally radiated electrical signals or from electrical interferences within the ultrasonic instrumentation. Electromametic Acoustic Transducer (EMAT) A device using the magneto effect to generate and receive acoustic signals for ultrasonic nondestructive tests. Far Field The region beyond the near field in which areas of high and low acoustic intensity cease to occur. First Leg The sound path beginning at the exit point of the probe and extending to the point of contact opposite the examination surface when performing angle beam testing. Focused Transducer A transducer with a concave face which converges the acoustic beam to a focal point or line at a d e f d distance from the race. LZ

Focusing Concentration or convergence of energy into a smaller beam. Frequency Number of complete cycles of a wave motion passing a given point in a unit time (1 second); number of times a vibration is repeated at the same point in the same direction per unit time (usually per second). -

Gate -

-

An electronic means to monitor an associated segment of time, distance, or impulse.

Ghost An indication which has no direct relation to reflected pulses from discontinuities in the materials being tested.

Emz (Hz)

One cycle per second.

Horizontal Linearity A measure of the proportionality between the positions of the indications appearing on the baseline and the positions of their sources. b

'Immersion Testing A technique of testing, using a liquid as an ultrasonic couplant, in which the test part and at least the transducer face is immersed in the couplant and the transducer is not in contact with the test part. Inspector's Handbook

5-4

Impedance (acoustic) A material characteristic defined as a product of particle velocity and material density. Indication(ultrasonics) The signal displayed or read on the ultrasonic systems display. Initial Pulse The first indication which may appear on the screen. This indication represents the emission of ultrasonic energy from the crystal face (main bang). Interface The physical boundary between two adjacent acoustic mediums. Insonification Irradiation with sound. Isotropy A condition in which significant medium properties (velocity, for example) are the same in all directions. Lamb Wave A type of ultrasonic vibration guided by parallel surfaces of thin mediums capable of propagation in different modes. Linearity (area) A system response in which a linear relationship exists between amplitude of response and the discontinuity sizes being evaluated necessarily limited by the size of the ultrasonic beam.

v

Linearity(depth) A system response where a linear relationship exists with varying depth for a constant size discontinuity. Longitudinal Wave Velocity The unit speed of propagation of a longitudinal (compressional) wave through a material. Loss of Back Reflection Absence of or a significant reduction of an indication from the back surface of the article being inspected. Maior Screen Divisions The vertical graticule used to divide the CRT into 10 equal horizontal segments. Manipulator A device used to orient the transducer assembly. As applied to immersion techniques, it provides either angular or normal incidence and fmes the transducer-to-part distance. Material Noise Extraneous signals caused by the structure of the material being tested. Miniature Angle Beam Block A specific type of reference standard used primarily for the angle beam method, but also used for straig w beam and surface wave tests. Inspeetor's Handbook

Minor Screen Divisions The vertical graticule used to divide the CRT into fifty equal segments. Each major screen division is divided into five equal segments or minor divisions. ; M o d e Conversion The change of ultrasonic wave propagation upon reflection or refraction at acute angles at an interface. Mode The manner in which acoustic energy is propagated through a material as characterized by the particle motion of the wave. Multiple Back Reflections Repetitive indications from the back d a c e of the material being examined. Nanosecond One billionth of a second. Narrow Banded A relative term denoting a restricted range of frequency response. Near Field. A distance immediately in front of a transducer composed of complex and changing wave front characteristics. Also known as the Fresnel field.

Node The point on the examination surface where the V-path begins or ends. L.

L40ise Any undesired indications that tend to interfere with t k interpretation or processinn- of the ultrasonic information; also referred to as "grass." Normal Incidence A condition where the angle of incidence is zero. Orientation The angular relationship of a surface, plane, defect axis, etc., to a reference p l w or sound entry surface. Penetration (ultrasonic) Propagation of ultrasonic energy through an article. Phased Array A mosaic of probe elements in which the timing of the element's excitation can be individuallv controlled to produce certain desired effects, such as steering the beam axis or focusing the beam. Piezoelectric Effect The characteristic of certain materials to generate electrical charges when subjected to mechanical vibrations and, conversely to generate mechanical vibrations when subjected to electrical pulses.


Polarized Ceramics Ceramic materials that are sintered (pressed), created (approximately 100oOc),and polarized by applying a direct voltage of a few thousand volts per centimeter of thickness. The polarization is the process that makes these ceramics piezoelectric. Includes sodium bismuth titanate, lead metaniobate, and several materials based on lea+ u zirconate titanate (PZT). Presentation The method used to show ultrasonic information. This may include (among others) A-, R,or C-scans displayed on various types of recorders, CRTs, LCD's or computerized displays. Probe Transducer or search unit. Propagation Advancement of a wave through a medium. Pulse Echo Technique An ultrasonic test technique using equipment which transmits a series of pulses separated by a constant period of time; e., energy is not sent out continuously. Pulse Len* Time duration of the pulse from the search unit. Pulse Rate For the pulse echo technique, the number of pulses transmitted in a unit of time (also called pulse repetition rate). ..r

Radio Frequency Display (RF) The presentation of unrectified signals in a display.

i.bxs

The maximum ultrasonic path length that is displayed.

Rarefaction The thinning out or moving apart of the consistent particles in the propagating medium due to the relaxation phase of an ultrasonic cycle. Opposite in its effect to compression. The sound wave is composed of alternate compressions and rehctions of the particles in a material. Raylei& WaveISurface Wave A wave that travels on or close to the surface and readily follows the curvature of the part being examined. Reflections occur only at sharp changes of direction of the surface. Receiver The section of the ultrasonic instrument that amplifies the electronic signals returning from the test specimen. Also, the probe that receives the reflected signals. Reference Blocks A block or series of blocks of material containing artificial or actual discontinuities of one or more reflecting areas at one or more distances *om the sound entry surface. These are used for calibrating instrume and in defining the size and distance of discontinuous areas in materials. 5-8

Inspector's EI.andbook

Reflection The characteristic of a surface to change the direction of propagating acoustic energy; the retun of sound 3-resfrom surfaces. L

Pehction A change in the direction and velocity of acoustic energy after it has passed at an acute angle through an interface between two different mediums. Refractive Index The ratio of the velocity of a incident wave to the velocity of the refhcted wave. It is a measure of the amount a wave will be refracted when it enters the second medium after leaving the first. Reiect/Suppression An instrument function or control used for reducing low amplitude signals. Use of this control may affect vertical linearity. Repetition Rate The rate at which the individual pulses of acoustic energy are generated; also Pulse Rate. Resolving Power The capability measurement of an ultrasonic system to separate in time two closely spaced discontinuities or to separate closely spaced,multiple reflections. Resonance Technique A technique using the resonance principle for determining velocity, thickness or presence of laminar L Siscontinuities. ,iesonance The condition in which the hquency of a forcing vibration (ultrasonic wave) is the same as the natural vibration frequency of the propagation body (test object), resulting in large amplitude vibrations. Saturation(scope) A term used to describe an indication of such a size as to exceed full screen height (100%).

Scanning (manual and automatic) The moving of the search unit or units along a test surface to obtain complete testing of a material. Scattering Dispersion of ultrasonic waves in a medium due to causes other than absorption Second Leg The sound path beginning at the point of contact on the opposite surface and extending to the point of contact on the examination surface when performing angle beam testing. Sensitivity The ability to detect small discontinuities at given distances. The level of amplification at which the receiving circuit in an ultrasonic instrument is set. Shear Wave The wave in which the particles of the medium vibrate in a direction perpendicular to the direction of propagation. Inspector's Handbook

5-

Signal-to-Noise Ratio (SNR) The ratio of amplitudes of indications from he smallest discontinuity considered significant and those caused by random factors, such as heterogeneity in grain size, etc.

-

,

u Skip Distance In angle beam tests of plate, pipe, or welds, the linear or surface distance from the sound entry point to the first reflection point on the same surface.

Snell's Law The law that defines the relationship between the angle of incidence and the angle of refkction across an interface, based on a range in ultrasonic velocity. Specific Acoustic Impedance A characteristic which acts to determine the amount of reflection which occurs at an interface and represents the wave velocity and the product of the density of the medium in which the wave is propagating. Straight Beam An ultrasonic wave traveling normal to the test surface. Sweep

The uniform and repeated movement of a spot across the screen of a CRT to form the baseline. Through-Transmission A test technique using two transducers in which the ultrasonic vibrations are ernitted by one and received by the other, usually on the opposite side of the part. The ratio of the magnitudes of vibrations transmitted and received is used as the criterion of soundness. ' 4 Tip Diffiction The process by which a signal is generated from the tip (i.e., top of a fatigue crack) of a discontinuity through the interruption of an incident sound beam propagating through a material. Transducer (search unit) An assembly consisting basically of a housing, piezoelectric element, backing material, wear plate (optional) and electrical leads for converting electrical impulses into mechanical energy and vice versa. Transmission Angle The incident angle of the transmitted ultrasonic beam. It is zero degrees when the ultrasonic beam is perpendicular to the test swface. Transmitter The electrical circuit of an ultrasonic instrument that generates the pulses emitted to the search unit. Also the probe that emits ultrasonic signals. Two Probe Method Use of two transducers for sending and receiving. May be either send-receive or through transmission. Ultrasonic Absorption A damping of ultrasonic vibrations that occurs when the wave transverses a medium.


Ultrasonic Spectrum The frequency span of elastic waves greater than the highest audible kquency, generally regarded as being higher than 20,000 hertz, to approximately 1O00 megahertz. 'Jltrasonic Svstem The totality of components utilized to perform an ultrasonic test on a test article.

V-path The vath of the ultrasonic beam in the test object from the point of entry on the examination surface to the back surface' and reflecting to the front surface again. Velocity The speed at which sound travels through a medium. Video Presentation A CRT presentation in which radio frequency signals nave been rectified and usually filtered. Water Path The distance fnrm the face of the search unit to the entry surface of the material under test in immersion testing. Wavelength The distance in the direction of propagation for a wave to go through one complete cycle. Wedgelshoe A device used to adapt a straight beam probe for use in a specific type of testing, including angle beam or d a c e wave tests and tests on curved surfaces. L Wraparound Nonrelevant indications that appear on the CRT as a result of a short pulse repetition rate in the pulser circuit of the test instrument.


Common Math Formulas

Wavelength

r

? = Wavelength

L I T

h

z = POI)

2

CT = Crystal thickne$s h = Wavelength

ER= 100 (-

Z = Acoustic impedance P = Materials density V = Acoustic velocity

Nearfield (nearzone)

Half Angle Beam Spread SIN

0=K( v )

N=

K= V= D= F=

1.22 Velocity of the material Diameter of the transducer Frequency of the transducer

N= D= F= V=

D*F

-

ET = El ER ET = Energy transmitted El = Energy intiated ER = Energy reflected

21-22 ) 2 21+22

ER = Energy reflected Z1 = Acoustic impedance material #1 22 = Acoustic impedance material #2

Use .23 if material is unknown Energy Transmitted

= Veloocity = Frequency

Reflected Acoustic Energy

Acoustic Impedance

Crystal Thickness CT =

V F

D * (F) 4 (V) Length of the near field Diameter of the transducer Transducer frequency Materials velocity

Times 2 for full angle beam spread Snell's Law & Angle of Reflection

Decibel Difference SIN 01 = A1 Db=20 [LOG (-)I A2

SIN 02 * V1 V2

Angle of incidence Critical angle* Wedge angle

Db = Decibel difference LOG = Natural logrithm A1 = Amplitude number one A2 = Amplitude number two

SIN 02 = 'IN

Rule of thumb: every 6 Db doubles the size of the

* V2 v1

indication height (pip)

5-12

Inspectar's Handbook

* 1st critical angle V2 is long = 90° 2nd critical angle V2 is shear = 90°

u

Half / Full Sound Path & Skip / Setback Distance HSP=

T COS 0

HALF SKIP = T TAN 8

FSP=

2T cos e

FULL SKIP = 2T * TAN 0

T =Member thickness

Surface Distance to Defect / Depth of Defect SDD = Sound Path * SIN 8

#DD = Sound Path * COS 8 ##DD = (Sound Path * COS 0) - 21

SDD Surface distance to defect #DD =Depth of defed during half sound path ##OD =Depth of defect during full sound path T =Member thickness

Calibration Chart - UT Shearwave b

PLATE THICKNESS 1"

PLATE THICKNESS I

*HALF SKIP 314" 1"

112"

-

1 112"

-

1 314"

FULL SKIP 2"

* Applicable holes in the M.I. block for calibration



Velocity Chart

I

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LONGITUDINAL

1

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SHEAR

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----

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24 41.6 18.9

I

.08 .I2 .I3

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1

10.09

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17 32 23

2.7

Aluminum Aluminum Oxide Bertilium KrTnCarbie I -,*,.,. v.x<,,,, ..",

Mercurv Molvbdenum Monel

ACOUSTIC

3.5 47.2 45.4

----

I

19.6 64.2 47.6

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----

Polyethylene Polvstyrene Polyurethane

Steel, Mild ,Steel, Stainless

Titanium Tungsten Uranium

1

----

I

7.7 8.03

4.54 19.25

----

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y

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$ !;% ? :>& ~@ &~ $?& ~

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46 45.4

27.3 101 63

I

Pnspector's Handbook

-

Chapter 6 Eddy Current Testing Common Terms and Definitions Absolute Coil b A test arrangement which tests the specimen without any comparison to either another portion of the test specimen or to a known reference. Alternating A voltage, current or magnetic field that reverses direction at regularly recurring intervals. Bobbin Coil A coil or coil assembly used for eddy current testing by insertion into the test piece; e.g., an inside probe for tubing. Also referred to as Inside Coil or IP Coil. Coil -

Conductor wound in one or more loops to produce an axial magnetic field when current is passed through

it. Coil Spacing The axial distance between two encircling coils of a differential system. /

Conductivity The willingness of a test circuit or test specimen to conduct current. Coupling A measure of the degree to which the magnetic field of the coil passes through the test specimen and is w ffkted by the magnetic field created by the flow of eddy currents. Defed Resolution A property of a test system which enables the separation of signals due to defects in.the test specimen that are located in close proximity to each other. Diamagnetic A material having a permeability less than that of a vacuum. Differential Coil A test arrangement which tests the specimen by comparing the portion being tested with either another portion of the same specimen or to a known reference specimen. Discontinuitv, Artificial Reference discontinuities, such as holes, grooves, or notches, which are introduced into a reference standard to provide accurately reproducible sensitivity levels for electromagnetic test equipment. Double Coil A test arrangement where the alternating current is supplied through one coil while the change in material condition is measured from a second coil. Eddy Current A circulating electrical current induced in a conductive material by an alternating magnetic field. L Inspector's Handbook

Edge or End Effect The disturbance of the magnetic field and eddy currents due to the proximity of an abrupt change in geometry (edge, end). The effect generally results in the masking of discontinuities within the affected region. f

Effective Depth of Penetration The depth in a material beyond which a test system can no longer detect a change in material properties.

d

Effective Permeability A hypothetical quantity which is used to describe the magnetic field distribution within a cylindrical conductor in an encircling coil. The field strength of the applied magnetic field is assumed to be uniform over the entire cross section of the test specimen with the effective permeability, which is characterized by the conductivity and diameter of the test specimen and test frequency, assuming values between zero and one, such that its associated amplitude is always less than one within the specimen. Electromagnetic Induction The process by which a varying or alternating current (eddy current) is induced into an electrically conductive test object by a varying electromagnetic field. Electromagnetic Testing That nondestructive test method for engineering materials, including magnetic materials, which uses electromagnetic energy having frequencies less than those of visible light to yield information regarding the quality of the tested material. Encircling Coil A coil, coils, or coil assembly that surrounds the part to be tested. Coils of this type are also referred to as circumferential, OD or feed-through coils. w

External Reference Differential A differential test arrangement that compares a portion of the test specimen to a known reference standard. Ferromagnetic A material which, in general, exhibits hysteresis phenomena, and whose permeability is dependent on the magnetizing force. Fill Factor For an inside coil, it is the ratio of the outside diameter of the coil squared to the inside diameter of the specimen squared. For an encircling coil, it is the ratio of the outside diameter of the specimen squared to the inside diameter of the coil squared. Flux Density A measure of the strength of a magnetic field expressed as a number of flux lines passing through a given area. Henry The unit of inductance. More precisely, a circuit in which an electromotive force of one volt is induced when the current is changing at a rate of one ampere per second will have an inductance of one henry. (Symbol: H) Hertz The unit of frequency (one cycle per second). (Symbol: Hz)

High Pass Filter An electronic circuit designed to block signals of low frequency while passing high frequency signals. IACS k

w

The International Annealed Copper Standard. A value of conductivity established as a standard against which other conductivity values are referred to in percent IACS. Impedance The ovtmsition to current flow in a test circuit or a coil due to the resistance of that circuit or coil, plus the of the coil as affected by the coil's magnetic field. electrical Impedance Analysis An analytical method which consists of correlating changes in the amplitude, phase, or quadrature components (or all of these) of a complex test signal voltage to the electromagnetic conditions within the specimen. Impedance-plane Diagram A graphical representation of the locus of points indicating the variations in the impedance of a test coil as a function of basic test parameters. Inductance The inertial element of the electric circuit. An inductor resists any sudden change in the current flowing through it.

b

Inductive Reactance The opposition to current flow in a test circuit or coil when an alternating voltage source is applied and due solely to the electrical properties of the mil as affected by the magnetic field. Inertia The property of matter which manifests itself as a resistance to any change in the momentum of a body. Lift-off The distance between a swface probe coil and the specimen. Lift-off Effect The effed observed due to a change in magnetic coupling between a test specimen and a probe coil whenever the distance between them is varied. Low Pass Filter An electronic circuit designed to block signals of high frequency while passing low frequency signals. Magnetic Field A condition of space near a magnet or current-carrying wire in which forces can be detected. Magnetic Flux Lines A closed curve in a magnetic field through points having equal magnetic force and direction. Noise

Any undesired signal that tends to interfere with the normal reception or processing of a desired signal.. In haw detection, undesired response to dimensional and physical variables (other than flaws) in the test part is called "part noise. Inspector's Handbook

6-3

Nonferroma.gnetic A material that is not magnetizable and hence, essentially not affected by magnetic fields. This would include paramagnetic materials having a magnetic permeability slightly greater than that of a vacuum and approximately independent bf the magnetizing force and diamagnetic materials having a permeability less tha- '' of a vacuum. V Paramagnetic A material having a permeability which is slightly greater than that of a vacuum, and which is approximately independent of the magnetizing force. Permeability A measure of the ease with which the magnetic domains of a material align themselves with an externally applied magnetic field. Permeability Variations Magnetic inhomogeneities of a material. Phase Analysis An instrumentation technique which discriminates between variables in the test part by the different phase angle changes which these conditions produce in the test signal. Phase Angle The angle measured cycle is equal to 360".

degrees that the current in the test circuit leads or lags the voltage. One complete

Phase Shift A change in the phase relationship between two alternating quantities of the same frequency.

w

Probe Coil Asmall coil or coil assembly normally used for surface inspections. -

Reference Standard A test specimen used as a basis for calibrating test equipment or as a comparison when evaluating test results. Reiection Level The setting of the signal level above or below which all parts are rejectable or in an automatic system at which objectional parts will actuate the reject mechanism of the system. Resistance The opposition to current flow in a test circuit or coil based on specific material properties and crosssectional area and length of a conductor. Response Amplitude The property of the test system whereby the amplitude of the detected signal is measured without regard to phase. Saturation The degree of magnetization produced in a ferromagnetic material for which the incremental permeabili has decreased substantially to unity. Inspector's Handbook

Self-comparison Differential A differential test arrangement that compares two portions of the same test specimen. Signal-to-noise Ratio The ratio of response or amplitude of signals of interest to the response or amplitude of signals containing L no usell information. Single Coil A test arrangement where the alternating current is supplied through the same coil from which the indication is taken. Skin Effect A phenomenon where, at high frequencies, the eddy current flow is restricted to a thin layer of the test specimen close to the coil. Standard A reference used as a basis for comparison or calibration; a concept that has been established by authority, custom, or agreement to serve as a model or d e in the measurement of &tity or the establishment of a practice or a procedure. Standard Depth of Penetration The depth in a test specimen where the magnitude of eddy current flow is equal to 37 percent of the eddy current flow at the surface.


6-5

Two Types of Electrical Current

Direct Current (DC)

4

-

Current flow is constant over time Current is distributed uniformly over the cross-section of the conductor Example: battery Current strength and direction remain constant over time

Time

Alternating Current (AC)

-

Current flow varies over time w Current flows at or near the surface of the conductor this phenomenon is called the SL, effect Example: 60 cycle ac in wall sockets

-

Current strength varies over time; current direction reverses every 112 cycle

Time

Inspector's Handbook'

Conductivity and the IACS

Conductivity of a metal is usually expressed as a percentage (%) and is based on the international annealed copper standard (IACS). k.

A specific grade of high purity copper was designated as 100 % conductivity. All other metals (except silver) are designated some % less then 100 %. These percentages indicate the relative efficiencies of the various metals for carrying electric current.

Right Hand Rule L

An easy method for fmding the direction of an electrically induced magnetic field is to imagine grasping the

conductor in the right hand with the thumb pointing in the direction of the current flow. The fingers will then point in the direction of the lines of force. This is the right hand rule and is shown below. From this figure it can be seen that the current flow in the conductor creates circular lines of force.

CURRENT FLOW

The coil's magnetic field intensity (strength) decreases with'in~reasin~ distance away from the outside of the coil. C*

C B A

The field intensity at point C is less than at point B, and point B's intensity is less than point A's


C1

The coil's field intensity (strength) is assumed to be constant across the inside diameter of the coil. This assumption is based on the use of AC and small diameter coils, and for all practical purposes the assumption is valid.

W'

'

Y

Lines of Force

\./-

The coil's magnetic field can be viewed as a distribution of lines of force around the coil. These lines of force are call magnetic flux, and represent the coil's magnetic force (symbol 'H'). Current in

-

Current out

- 0 -

C.--

0

I

When a metal rod is placed inside the coil, the coil flux passes through the rod. The number of lines of force in the rod divided by the cross-sectional area of the rod equals the flux density (symbol 'B') in the rod. The flux density in the rod depends on the metal's willingness to cany the magnetic flux. The metal's willingness to carry these magnetic flux lines is called permeability. The symbol for permeability is 'p'(mu).

'N

/ \

,'

' N-*

---I-

w

Mathematically, permeability is expressed as the flux density in the material (B) divided by the magnetizing force (H) that caused it.

Flux densih Magnetizing force

B

Permeability = o r p H

Like conductivity, permeability is a material property that is the same for all samples of a particular material (assume same chemistry, etc.). example:

p, for air = 1 p for copper alloys = 1 p, for steels = several thousand

The permeability value of 1 for air and copper alloys (and all other nonmagnetic materials) means that the magnetic flux in the material is exactly equal to the flux coming from the coil. b

stated another way:

b/h = 1 only when b = h

The high permeability value of steels (and all other ferromagnetic metals) means that the magnetic flux in the metal is thousands of times greater than the applied flux fiom the coil. stated another way:

b/h = 2000 means h,, = 2000 x h,,

Magnetic Domains

Obviously, something is happening in the ferromagnetic metals to create all this additional flux that is not happening in the nonmagnetic materials. Magnetic domains are groups of atoms within a ferromagnetic metal which behave like tiny permanent magnets.

.

w

In unmagnetized magnetic materials, the domains are randomly oriented and neutralize each other, producing no observable magnetic flux in the metal.

When the magnetizing force fiom the coil, is applied, the domains begin to align in the direction of the applied flux. Their combined individual magnetism starts to produce an observable increase in the flux in the metal, over and above the applied flux (H).

Partially Oriented Domains

When the domains are completely aligned, the metal is said to be saturated, and the flux 'B' is many thousands of times greater than the applied flux 'HI. This domain behavior is responsible for the mrrlinear relationship between (E3) and (H) in ferromagnetic metals and for the hysteresis effect.

Completely Oriented Domains (saturation) Inspector's Handbook

When a coil of wire carrying alternating current is brought into proximity to a conducting article. The alternating magnetic field that surrounds the coil will penetrate the article, generating small circulating electrical currents, called eddy currents, in an article.

Note: When a generator's electrical current reverses it direction, the direction of the eddy currents will ako reverse.

II II

Electrical current

$4

Test coil

Article being tested

Eddy currents are circulating electrical currents induced in an isolated conductor by an alternating magnetic field. Note that there is no direct electrical contact between the coil and the test article - eddy currents are generated by electromagnetic induction. The "primary" magnetic field surrounding the ac coil will penetrate the test articles and induce eddy c m t s in the article. The circulating eddy currents possess their own "secondary" magnetic field. This secondary field will oppose the coils and reduce the size and strength of the coil's field.

Direction of coil's field

Ac

. \

Inspector's I F a n h k

1 I

I

.

A

,

--*#

Eddy current field opposes coil's field

Changes in the strength or shape of the secondary field will affect the primary field, which will affect the AC flowing in the coil, where it will be sensed. LTn this way, variations of the test article that disturb or alter the flow of the eddy currents will disturb the electromagnetic coupling between the two fields and cause indications on the test instnunent

Test circuit

Change in coil's impedance

Changes in conductivity

Change in coil's magnetic field

-

Change in meter reading

-------------.----I------------------Material

Characteristics of Eddy Current

1) Can only be induced in conductors Coated (i.e. painted) articles may be tested, since the coils field will pass through the nonconducting coating and generate eddy currents in the metal beneath.

&@) \

onc conductive

material

\e

1--conductive

Plated articles should not be tested, since the coil's field will generate eddy currents in both the metallic plating and the base material. Consequently, ET indications could originate from either the base metal or the plating, confusing the inspection.

material

*Conductivematerial

-Conductive

mate

-

2) Can be generated only by an alternating magnetic field there must be relative motion between the field and the test article. A DC field will not generate eddy currents. The moving AC field which builds up, then breaks down and reverses direction every 112 cycle, is essential to the production of eddy currents. 3) Eddy currents flow in circular paths, parallel to the coil windings.

/ENCIRCLING

COIL

CRACK

EDDY CURRENTS

Depth of Penetration

Eddy currents are strongest at the surface nearest the coil (due to skin effect) and weaken with depth. The depth of eddy current penetration below the surface is directly affkcted by the nearness of the coil to the test article, the operating frequency, and the test article conductivity and permeability. I

4

(A) Coil position - since the coil's field is limited in size and decreases in strength with increasing distance away from the coil, maximum field penetration into the article and, therefore, maximum depth of eddy current penetration is achieved by mving the coil as close as practical to the test article surface. 02,

II '8

\\

coil far away from article being tested

/='

1

+

71 1

I

possible to the article being tested

(B) Operating frequency - a relationship also exists between the frequency of the ac applies to the test coil and the eddy current depth of penetration. As the frequency is increased, eddy current distribution concentrates near the surface and decreases deep with the test article. The reverse is also true. As the frequency is lowered, the eddy current distribution extends deeper into the article. Frequency \

Depth of

-

Depth of Eddy Current Penetration

Penetration I

I

View A

View B

In both view A and B above, the material and the test coil are the same. Since view a shows deeper eddy current penetration into the material, this means that a lower frequency was used. View B shows shallower penetration, so a high frequency was used. Keep in mind that a high frequency causes the eddy currents to accumulate near the surface closest to the test coil.

-

c) Conductivity the figure below illustrates that the depth of eddy current penetration also varies with metal's electrical conductivity. As conductivity increases, the depth of eddy currents decreases. 'c/

Indicator

Indicator oil

Indicator Coil

oil .':.:.'::.:;:.:

-

Depth of Eddy Current Penetration

Depth of Eddy Current Penetration Lead

:.:-.::.:::.:. .... .:..::.,:.....

Tin

2

:.

copper

In the figure, the coil and test frequency are the same in each view. Only the material type is different. You can verifl that tin is more conductive the lead, and that copper is much more conductive than either, by referring to the % IACS conductivity chart shown earlier. As the figure shows, the less conductive metals achieve deeper eddy current penetration than the more conductive metals.

-

d) Magnetic permeability f d y , a metal's magnetic permeability (p) affects the depth of eddy current penetration. The depth of penetration decrease as the permeability increases. There are 3 basic types of eddy current test: surface ,encircling ,and inside. A surface coil is designed to be used on localized areas on a surface, and is usually contained in a hand-held probe. 'L

An encircling coil, on the other hand, is large enough to surround an object about one of its axes and is designed to test an entire segment of the object at one time.


Encircling Coil

An inside coil is designed to be placed inside a hole or cavity in the object, and is especially suited for testing thin wall tubing.

ARTICLE

bb$Lc L , oc , - INSIDE COIL

Note that with each of the coil types: - The eddy currents circulate parallel to the coil windings The eddy currents hug the surface that is nearest the coil

-

Each of these 3 coil types may be used in either the differential or absolute test mode.

In the differential coil arrangement, two side-by-side coils are wound and connected so that the output of on cancels the output of the other as long as the test object properties are the same under both coils. This mode is most ensitive to small defects and is relatively insensitive to material variations such as hardness, gross surface megularities, etc. P1

DIFFEREN TlAL

In the absolute mode, a single coil tests the area of the test object beneath it without comparison to a reference area This mode is most sensitive to large defects longer than the coil, and to material variations such as hardness, gross surface irregularities, etc. A B S O L U T E COIL

The 3 general material variables (properties) that affect the flow of eddy currents in the material are: 1) Changes in conductivity - conductivity changes may be caused by variations in alloy chemistry or heat treatment, or may be due to the presence of defects. Since cracks or other discontinuities force the eddy currents to take a longer path by flowing around them, the overall effect of the discontinuity is to reduce the conductivity of the metal.

EDDY CURRENT MAGNETIC FIELD

TEST COI L MAGNETIC F I E L D E D D Y CURRENT

E D D Y CURRENT

,TEST COIL MAGNETIC FIELD

CRACK

As the figure illustrates, the eddy currents must flow around the crack, effectively reducing the conductivity of the metal.

2) The second material variable affecting eddy current flow is magnetic permeability. Eddy currents are induf ' ' 4 by flux changes in the metal and are directly related to the density or amount of flux. Since changes in permeability cause changes in the amount of flux in the metal, they also cause a pronounced (and detectable) change in the eddy current flow. 3) Changes in the physical dimensions, or size and shape of the test object also affect the eddy current flow. Although the figure below is a gross example, it clearly illustrates how a change in physical dimension can alter the electromagnetic coupling between the coil and the object.

Two more dimensional of eddy current testing is edge effect and lift-off. Edge effed is the false indication caused by disruption of by disruption of the eddy current path when the coil approaches an end or edge of the material. w

The effect is strong enough to "mask' any changes due to other factors. In effect, the edge of the material looks h e a very large crack to the eddy current instrument. On the other hand, the false indication caused by changing the spacing between the test coil and the material d a c e is called lift-off.

-------------' \

MAGNETIC


Lift-off has a very large effect on the ET output display due to the decrease in primary field flux in the material as the coil distance from the materials surface is increased.

The lift-off effect can be used to measure the thickness of nonconducting coatings, such as paint, on a conducting object.

WONCONDUC SURFACE I

1

CvnOUCTlVE MATERIAL

I

I

ARTICLE

b

A c e eddy currents cannot be generated in the nonconductor, a coil placed in contact with the painted surface "sees" the paint thickness simply as lift-off distance. Another important relationship between eddy current flow and the presence of discontinuities is that the discontinuity must lie perpendicular to the direction of eddy current flow to be detected.

\

'

SURFACE CRACK

SUBSURFACE LAMINAR SEPARATION

INSPECTION COIL EDDY CURRENTS

-

In the situation above, a surface coil passes over a surface crack and a subsurface lamination in the metal. It is easy to see that the crack will force the eddy currents to take a longer path around it, causing a detectable disruption in their flow. The lamination on the other hand, will not cause much disruption of the eddy current path since the . netal separation lies parallel to the direction of current flow. Inspector's Handbook

6-17

Limitations of Eddy Current Testing 1. Inspect only conducting articles (i.e. metals). 2. Can locate only d a c e and shallow subsurface discontinuities; inspection depth is limited to less then 1 ii.

3. Separation of the effects of conductivity, permeability, and dimension variables is difficult and often not possible. 4. ET is an indirect inspection requiring the use of calibration standards; you must know what you are looking for in order to find it. Advantages of Eddy Current Testing 1. Able to inspect through nonconductive coatings (i.e. paint). 2. Fast, real-time inspection.

3. Totally nondestructive; no interference with the test item.

Summary of Properties of Eddy Currents

1. Generated by an alternating magnetic field. 2. Flow only in conductors.

4

3. Circulates parallel to coil windings.

4. Eddy current flow is affected by changes in the material's conductivity, dimension, magnetic permeability. 5. Limited to surface/shallow s u b d a c e testing. 6. Depth of penetration is affected by conductivity and permeability of test object, by test frequency, and by nearness of the coil to the test object. 7. Able to test through surface coatings (nonconducting) but not through plating (metal).

Eddy Current Relationship of Properties Penetration Decrease Increase

Frequency Increase Decrease

Conductivity Increase Decrease


Permeability Increase Decrease

Chapter 7 - Radiographic Inspection Common Definitions and Examples w Absorbed dose

The amount of energy imparted to matter by an ionizing particle per unit mass of irradiated material at the place of interest. It is expressed in "'rads." Accelerator A device that accelerates charged atomic particles to high energies. An x-ray machine is an accelerator. Activity A measure of how radioactive a particular radioisotope is. The number of atoms decaying per unit of time calculates activation. Its unit of measurement is the "curie." Alpha particle A positively charged particle emitted by certain radioactive materials. It is made up of two neutrons and two protons; hence it is identical with the nucleus of a helium atom. Alpha ray A stream of fast-moving helium nuclei (alpha particles). This radiation is strongly ionizing with very weak penetration. An~strom A unit of length used to express wavelength. One angstrom equals lo-* centimeters. W e (target side) The positive terminal of an x-ray tube. It is a high melting point element that receives the electron bombardment from the cathode (filament).

-Q.

Atom The smallest part of an element. The atom consists of a nucleus composed, with the exception of hydrogen, of a number of protons and neutrons. Included in the atom is an extranuclear portion composed of electrons equal in number to the protons in the nucleus. The hydrogen atom includes a nucleus of one proton and extranuclear portion of one electron. Autotransformer A special type of transformer in which the output voltage can be easily varied. The autotransformer is employed to adjust the primary voltage applied to the step-up transformer that produces the high voltage applied to the x-ray tube. Background radiation The radiation of man's radiation natural environment, consisting of radiation that comes from cosmic rays and from the naturally radioactive elements of the earth, including radiation from within man's body. The term may also mean radiation extraneous to an experiment.

,

'

Backscatter Radiation scattered h m the floor, walls, equipment, and other items in the area of a radiation source. Sackscatter includes secondary radiation resulting from the interaction between the primary radiation from the source and the material being radiated. Inspector's Handbook

Beta particle An electron or position emitted from a nucleus during radioactive decay. Bremsstrahlung ~lectroka~netic radiation (photon) emitted by charged particles when they are slowed down by e l e d fields in their passage through matter. Literally means, "braking radiation" in German.

L-

200 Kev Electron Leaving

8

400 Kev Electron

200 Kev X-Ray

A lightproof container, which may or may not contain intensifying andlor filter screens, that is used for holding the radiographic films in position during the radiographic exposure. Cathode (filament side) The negatively-biased electrode of the x-ray tube.

's/

A device used to surround a radiation source and so constructed as to both minimize the scattered radiation and to direct the primary or useful radiation into a more or less parallel beam onto a localized area. Compton Effect The glancing collision of an x-ray or gamma ray with an electron to an orbital electron in matter with a lower enxgy in matter with a lower energy photon scattered at an angle to the original photon path. The electron does not absorb all of the energy. Ejected electron

/

High energy Photon 0e

/

de-. \

1

4

I

'

-

.

/@-o-.

e'L--

I

Photon continues with less energy

\

\ \


\

\

' \

Contrast (film) The change in density recorded on the film that results from a given change in radiation input. Contrast is determined h t h e slope of the characteristic curve. Tontrast (radiographic) The measure of difference in the film blackening resulting from various x-ray intensities transmitted through the object and recorded as density differences in the image. Thus, difference in film blackening from one area to another is contrast.

L

Contrast (subiect] The ratio of radiation intensities passing through selected portions of a specimen. Definition The measure of sharpness in the outline of the image of an object recorded on film, the sharpness is the function of the types of screens, exposure geometry, radiation energy and film characteristic. Densitometer An instrument utilizing the photoelectric principle to determine the degree of darkening of developed photographic film. Developer A chemical solution that reduces exposed silver halide crystals to metallic silver. Dose -

The amount of ionizing radiation energy absorbed per unit mass of irradiated material at a specific location, such as a part of the human body.

'Y Dose rate

The radiation dose delivered per unit time and measured, for instance,in rems per hour. Dosimeter A device that measures radiation dose, such as a film badge or ionization chamber.

Duty cvcle Usually expressed in a percentage to represent the time used versus the time not used. Electromametic Spectrum Represents the electromagnetic waves of different wave lengths. The lines are not definie boundaries but rather phase into one another. X-RAYS AND GAMMA RAYS

ULTRAVIOLET RAYS

DECREASING INCREASING L

INCREASING

LIGHT RAYS

-

INFRARED RAYS

WAVELENGTH FREQUENCY ENERGY

RADAR

SHORT WAVE RADIO

-


LONG WAVE RADIO

INCREASING

DECREASING DECREASING

7-3

Electron volt Is an amount of energy equal to the energy gained by one electron when it is accelerated by one volt. Emulsion A gelatin and silver bromide crystal mixture coated onto a transparent film base.

Encapsulation The process of sealing radioactive materials to prevent contamination. Filament A piece of wire in the cathode side, negative side, of the x-ray tube used to produce electrons when heated. Specialized film used for radiographic purposes. The components of the film are two protective layers, two emulsion layers, and one acetate base layer.

,...........

............

acetate base

t

protective layers

Film b a d ~ e A package of photographic film worn as a badge by workers in the nuclear industry to measure exposure to ionization radiation. The absorbed dose can be calculated by the degree of film darkening caused by the irradiation. Filter A layer of absorptive material that is placed in the beam of radiation for the purpose of absorbing rays, certain wavelengths and thus controlling the quality of the radiograph.

Fixer -

.d

A chemical solution that dissolves unexposed silver halide crystals from developed film emulsions.

Fon

A darkening of the film resulting from chemical action of the developer, aging, scattered or secondary radiation, pre-exposure to radiation, or exposure to visible light.

Geiger counter A radiation detection and measuring instrument. It contains a gas- filled tube that discharges electrically when ionizing radiation passes through it. Discharges are counted to measure the radiation's intensity. Graininess A film characteristic that consists of the grouping or clumping together of the countless small silver grains into relatively large masses visible to the naked eye or with slight magnification. Half-life The time in which half the atoms in a radioactive substance decay. Time is dependant upon the element. Half- life (biological) The time required for a biological system, such as a man or an animal, to eliminate, by natural processr half the amount of a substance that has entered it. 7-4


_c

Hal6 value layer The thickness of a material required to absorb one half of the impinging radiation. Intensifying screen A layer of material placed in contact with the film to increase the effect of the radiation, thereby shortening 'v h e exposure. F

Interlock A device for precluding access to an area of radiation hazard either by preventing entry or by automatically removing the hazard. Ion -

A charged atom or molecularly-bound group of atoms; sometimes also a free electron or other charged subatomic particles.

Ion pairs A positive ion and a negative ion, or electron, having charges of the same magnitude and formed from a neutral atom or molecule by the action of radiation or by any other agency that supplies energy. Ionization The process of adding electrons to, or knocking electrons from, atoms or molecules thereby creating ions. and nuclear radiation can cause ionization. High tempe~tures,ele~tricaldischar~es, Ionization chamber An instrument that detects and measures ionizing radiation by observing the electrical current created when radiation ionizes gas in the chamber making the gas a conductor of electricity. ,onizing radiation Any radiation that directly or indirectly displaces electrons from the orbital shells of atoms.

v& The energy of X-rays or gamma rays measured in thousand electron volts. Latent image The potential image that is stored in the form of chemical changes in the film emulsion and is brought out by development of the film. Latitude Latitude most closely aligned with contrast is commonly called the scale of the film. Latitude is the range of thickness of material that canbe transferred or recorded on the radiograph within the usell reading range of film density. A high contrast film has little latitude and conversely a low contrast film has great latitude. Leak test A test on sealed sources to assure that radioactive material is not being released.

Licensed material Source material, special nuclear material, or by-product material received, possessed, used, or transferred under a general or speciailicense issued by the Nuclear Regulatory Commission.


7-5

Mev -

The energy of X-rays or gamma rays measured in million electron volts.

Microshrinkage Cracks that appear as dark feathery streaks, or irregular patches, that indicate cavities in the grain boundaries.

\

w

Monochromatic radiation A rare condition, hypothetical, in which all gamma rays oi x-rays produced are of the same wavelength. Pair production The transformation of a high-energy ray into pair of particles (an electron and a positron) during its passage through matter. Particle A minute constituent of matter with a measurable mass, such as a neutron, proton, or meson. Penetrameter A small strip of material of the same composition as the specimen being tested. Its thickness represents a percentage of the specimen thickness. When placed in the path of the rays, its image on the radiograph provides a check on the radiographic technique employed.

T = thickness 4TDIA T DIA

I

k

2T DIA I

I

Penumbra The shadow cast when the incident radiation is partly, but not wholly, cut off by an intervening body; t space of partial illumination between the umbra, or perfect shadow, on all sides and the fidl light.

-

Photoelectric effect This process involves the complete absorption of the photon during the process of knocking an electron out of orbit. It occurs primarily with lower energy X-rays photons of 10 Kev to 500 Kev.

/ e Ejected electron ..a

(negative ion)

Approaching Photon Photon absorbed

4-. \ g4-' ' 0

/

/

/

\

@

.\

\

/

'

\

\

I

\

' \ \

\

\

'.-- ',' 0

\

\

/

--e4 '

Charged atom (positive atom)

Photon

4

A discrete quantity of electromagnetic energy. Photons have no momentum but no mass or electrical charge. 7-6


Positron A hdamental atomic particle having a mass equal to that of the electron and possessing a positive charge equal to the negative charge of the electron. <

'VRoentaen A unit of exposure dose of ionizing radiation. It is that amount of gamma or x-rays required to produce ions carrying 1 electmst&ic unit of electrical charge in one cubic centimeter of dry air under standard conditions. Safelight A special lamp used in the darkroom to provide working visibility without affecting the photosensitive emulsion of the radiographic film. Scatter Secondary radiation that is emitted in all directions. Screens Metallic or fluorescent sheets used to intensify the radiation effects on films. Sensitivity A term usually referring to the ability of the radiographic procedure to detect discontinuities. Specific activity Total radioactivity of a given isotope per gram of element. Source-film-distance The distance between the focal spot of an x-ray tube or radiation source and the film, generally expressed .n inches. Tar~et The piece of material, usually tungsten, embedded in the anode side, positive side, of the x-ray tube.A effective and efficient target has the following four properties high atomic number, high melting point, high thermal conductivity, and low vapor pressure. Two- film technique A procedure wherein two filmsof different relative speeds are used simultaneously to radiograph both the thick and the thin sections of an item.


Structure of the Atom and an Element $

0

Proton - A heavy atomic particle with a positive charge. Neutron - Close to the same weight and size of the proton with a neutral charge. Electron - A negative charged particle weighing about 111840'~of a proton or a neutron.

Nucleus - The proton(s) and ~utron(s)are group here in the center of the atom. Atomic number "Z"- This number represents the number of protons in the atom. Mass number "A" - This number represent the number of protons and neutrons in the atom.

fi

Helium Atom

E = element symbol Z = atomic number A = mass number

Components of an Isotope

Isotope - One or more of the same element having the same number of protons but not the same number of neutrons. Natural isotopes - Those that occur naturally. Artificial isotope - Those elements that are created by bombarding with swarms of neutrons. Activation - This is the process of creating artificial isotopes. Stable isotopes - Atoms that are not radioactive. Unstable isotopes - Atoms that are radioactive.

v/

Characteristics of A Radioactive Element

During the decay or disintegration process tiny particles of energy are emitted in the form of particles and waves h m the nucleus. Alpha particles (a) - The biggest and heaviest of the radiation particles and is composed of two protons and two neutrons. Beta particles (13) - A very light particle, actually a high-speed electron. Gamma rays (?) - A form of energy that is a wave not a particle. Two Types of Radiation

Gamma radiation - A product of nuclear disintegration or decay of radioactive elements. X-rays - An artificial produced wave from a high voltage electron tube. 1) Soft x-rays - low energy. 2) Hard x-rays - high energy.


History of Radiography

-

X-rays were discovered in 1895 by Wilhelm Conrad Roentgen (1845- 1923) who was a Professor at Wuerzbug University in Germany. Working with a cathode-ay tube in his laboratory, Roentgen observed a fluorescent glow of crystals on a table near his tube. The tube that Roentgen was working with consisted of a glass envelope (bulb) with electrically positive and negative electrodes encapsulated in it. The tube was evacuated of air, and when a high voltage was applied to it, the tube would produce a fluorescent glow. Roentgen shielded the tube with heavy black paper, and found that a green colored fluorescent light could be seen from a screen setting a few feet away from the tube. He concluded that a new type of ray emitted from the tube. This ray was capable of passing through the heavy paper covering. He also found that the new ray would pass through most substances casting shadows of solid objects. In his discovery, Roentgen found that the ray would pass through the tissue of humans leaving the bones and metals visible. One of Roentgen's first experiments late in 1895 was a film of his wife, Bertha's hand with a ring on. However, it can be argued that the fkst use of X-rays was for an industrial (not medical) application as Roentgen produced a radiograph of a set of weights in a box to show his colleagues. Roentgen's discovery was a scientific bombshell, and was received with extraordinary interest by both scientist and laymen. Scientists everywhere could ,duplicatehis experiment because the cathode tube was very well known during this period. Many scientist dropped other lines of research to pursue the mysterious rays, and the newspapers and magazines of the day provided the public with numerous stories, some true, others fanciful, about the properties of the newly discovered rays. The public fancy was caught by the invisible ray with the ability to pass through solid matter, and, in conjunction with a photographic plate, provide a picture, albeit a shadowy diffuse one, of the bones and interior of the body. Scientific fancy was captured by an extraordinary new radiation, of shorter wavelength than light, that presaged new and great vistas in physics, and the structure of matter. Both the scientist and the public were enthusiastic about potential applications of the newly discovered rays as an aid in medicine and surgery. Thus,within a month after the announcement of the discovery, several medical radiographs had been made & Europe and the United States that were used by surgeons to guide them in their work. In June 1896, only 6 months after Roentgen announced his discovery, X-rays were being used by battlefield physicians to - locate bullets in wounded soldiers.

Prior to 1912, X-rays were used little outside the realms of medicine, and dentistry, though some X-ray pictures of metals were produced. The main reason that were not used in industrial application before this date was because the X-ray tubes (the source of the X-rays) of that period broke down under the voltages required to produce rays of satisfactory penetrating power for industrial purpose. However, that changed in 1913 when the high vacuum X-ray tubes designed by Coolidge became available. The high vacuum tubes were an intense and reliable X-ray sources, operating at energies up to 100,000 volts. In 1922, industrial radiography took another step forward with the advent of the 200,000-volt X-ray tube that allowd radiographs of three inches thick steel parts to be produced in a reasonable amount of time. In 1931, General Electric Company developed 1000,000 volt X-ray L/ qenerators. That same year, the American Society of Mechanical Engineers (ASME) permitted X-ray approval of fusion welded pressure vessels. Inspector's Handbook

7-9

Shortly after the discovery of X-rays, another form of penetrating rays was discovered. In 1896, French scientist Henri Becquerel discovered radioactivity somewhat by accident, like many other great scientific discoveries. Many of the scientists of the period were working with cathode rays, and other scientists were gatherin~gevidence on the theory that the atom could be subdivided. Some of this new evidence showed that cer'qi/ types of 'atoms disintegrate by the rnselves. It was Henri Becquerel who discovered this phenomenon while d :ulvcar~~ating --.--+: the properties of fluorescent minerals. Becquerel was working on the principles of fluorescence, certain Iminerals glow (fluoresce) when exposed to sunlight. He utilized photographic plates to record this fluoresc:ence.

-

One of the minerals Becquerel worked with was a uranium compound. On a day when it was too cloudy to expose-his samples to direct sunlight, Becquerel stored some of the compound in a drawer with photographic dates. When he developed these plates a couple of days later, he discovered that they were fogged. Becquerel questiorled whalt would have caused this fogging. He knew he had wrapped the plates tightly before using them, sothe fog* g was not due to stray light. In addition, he noticed that only the plates that were in the drawer with the -umuum compound were fogged. Becquerel concluded that the uranium compound gave off a type of radiation that could penetrate heavy paper and affect photographic film.Becquerel continued to test many samples of uranium compounds and determined that the source of radiation was the element uranium. At this time, enough information was gathered to determine that an element, which gives off radiation, is said to be radioactive, and possesses the property of radioactivity. Becquerel's discovery was, unlike that of the X-rays, virtually unnoted by the layman and scientist alike. Only a relatively few scientist were interested in Becquerel's findings, and it was not until the discovery of radium by the Curies two years later that interest in radioactivity became wide spread. I

A

--

.- -. ...

.. ..

While working in France at the time of Becquerel's discovery, Polish scientist Marie Curie became very interested in his work. She too, suspected that a uranium ore known as pitchblende contained other radioactive elements. Marie and her husband, a French scientist, Pierre Curie started looking for these other elements. In 1898, the Curies discovered another radioactive element in pitchblende; they named it 'polonium' in honor of Marie Curie's native homeland. Later that same year, the Curie's discovered another radioactive element for which the*named 'radium', or shining element. Both polonium and radium are more radioactive than uranium. Since thes~ discoveries, many other radioactive elements have been discovered or produced.

-

The initial gamma ray source was radium, which allows radiography of castings up to 10 to 12 inches thick During World War 11, industrial radiography grew tremendously as part of the Navy's shipbuilding program. Shortly after the war, manmade gamma ray sources such as cobalt and iridium became available in 1946. These new sources were far stronger than radium sources and were less expensive. Thus the manmade sources rapidly replaced radium, and the use of gamma rays grew quickly in industrial radiography.

7-10


60" Coverage for Pipes and Location Marker Measurements

II

General Information

I

Outside Circumference 60" L~ NPS Diameter (OD times pi) Coverage

1

Distance Between Location Markers (centerline)

5

6

7

8

9

10

I1

12

Outside Circumference

k.4.


7-11

Common Math Formulas Ii(D1)

= 12(D2) 2

Ma,

-- Ma, (SFD

Ma

-- Ma,

,) 2

(SFD

1

2

2

(SFD 2 ) 2

(SFD

1

)

Ma=Milliamperage SFD=Source to film distance

,J",:'","

a, =

SFD ,=

a,

(SFD 1 ) 2 2

(SFD

SFD

,

a

, (SFD

)

) (SFD

a 2

Ci=Curie SFD=Source to film distance


1

)

Ef, =

Ef, (SFD

,

2

2

)

(SFD Ef

(SFD 2 ) '

(SFD

)

Ef, =

Ef=Exposure factor SFD=Source to film distance

SFD

;i'

T 2 (SFD 1 ) 2 1

T2

SFD

T 1 (SFD 2 ) 2

-

(SFD

1

)

T=Time SFD=Source to film distance

OF, (SFD OF,

)

= 2

(SFD

;i'

OF

SFD

OF

2

)

(SFD

)

'

OF, =

(SFD 2 )

(SFD

OF 2

1

)

OF=Offset SFD=Source to film distance


7-13

(TS + GAP) x OM SFD = new SFD TS TS=Depends on technique used SFD=Source to film distance GAP=Film to specimen distance

7

(TM or TS) X DS MS TM)=Thickness (TM if location marker is on TM) DS=Defect shift MS=Marker shift

Dm( Efi) = Dm ( Efl) Dn=Densitv Ef=Ex~osurefactor

-

FSS = IS (2 X PHs) FSS=Focal spot size IS=lmage size PHS=Pin hole size

Adding / Removing Shielding

I = Intensity after adding shielding 10 = Original intensity HVL = # of Half-value layers added

Determining Shielding Required h

HVL =

I = Intensity after removing shielding 10 = Original intensity HVL = # of Half-value layers added

Common Half-ValueLayers for IRl 92 Concrete Steel Lead Tungsten

(IA ) .693

HVL = # of HVCs required to reduce intensity In = Natural logrithm lo = Original intensity I= Desired intensity

Kodak Radiographic Films Type

R M T

Decay Fomula

AA A = New activity Ao = Original known activity n = TlHL T = Time passed since known activity passed HL = Half-life of the isotope

1.75" .500" .190" .130"

Speed 8 4 2 1

Grain Ultra fine Extra fine Extra fine Fine

Gamma Radiation Exposure Calculator Experienced Based Roentgen Factors (Steel) I T D E N S 1.0 1.5 2.0 2.5 3.0 F I AA .652 .730 1.0 1.25 1.55 T 1.3 1.46 2.0 2.5 3.1 L 2.6 2.92 4.0 5.5 6.2 M M


Y 4.0 2.4 4.8 9.6

d

Magic Circles

Ef-Exposure factor Ma=Milliamperage T=Time

D=Dose DR=Dose rate T=Time

EeExposure factor Ci=Curie T=Time

L

Single Wall Exposure 1 Single Wall Viewing for Plate

I

SWE 1 SWV (PLATE)

1

Film Pb "B"

TM PENNY SHIM

= DESIGN MATERIAL THICKNESS = BASED ON Tm = BASED ON (1) WELD AND (1) ROOT REINFORCEMENT

SFD ENERGY

= BASED ON Ts = BASED ON Ts


7-15.

Single Wall Exposure 1 Single Wall Viewing for Pipe

I

*

1

SWE ISWV (PIPE) Source

Film Pb "6"

TM = DESIGN MATERIAL THICKNESS PENNY = BASED ON Tm SHlM = BASED ON (1) WELD AND (1) ROOT REINFORCEMENT SFD = BASED ON Ts ENERGY = BASED ON Ts

Double Wall Exposure 1 Double Wall View (superimposed)

I

*

DWE 1 DWV Source

I

I

Film Pb "B"

TM PENNY SHlM

= DESIGN MATERIAL THICKNESS = BASED ON (2) Tm = BASED ON (2) WELD AND (2) ROOT REINFORCEMENT

SFD ENERGY

= BASED ON OUTSIDE OD = BASED ON (2) Tm, (2) WELD AND (2) ROOT REINFORCEMENTS

I

* I

Double Wall Exposure / Double Wall View (offset)

I

-

Tm

Source

F

+%

DWE I DWV

Consumable lnsert

I

I

markers

I

I

Film

I

Pb "B"

TM = DESIGN MATERIAL THICKNESS PENNY = BASED ON (2) Tm SHlM = BASED ON (1) WELD AND (1) ROOT REINFORCEMENT SFD = BASED ON OUTSIDE OD ENERGY = BASED ON (2) Tm, (1) WELD AND (1) ROOT REINFORCEMENT

-

Double Wall Exposure / Single Wall View DWE I SWV

I

Consumable Insert

Film

Pb "B"

u

TM = DESIGN MATERIAL THICKNESS PENNY = BASED ON (1) Tm FILM SIDE PENNY CHART SHlM = BASED ON ( I ) WELD AND (1) ROOT REINFORCEMENT SFD = BASED ON (1) Ts ENERGY = BASED ON (2) Tm, (1) WELD AND (1) ROOT REINFORCEMENT

Inspectds Handbook

I

KILLER CARL

Penetrameter Material and Group Numbers

Magnesium

Aluminum

Titianium

.?1GROUP01

S-51.S-52,s-53

Carbon steel Alloy steel Stainless steel Manganesse-nickel-aluminum bronze

.

S-I 1C. S-11 D. S-36B, S-37A.

Aluminum bronze

11

Nickel-chromiumiron alloy

V~GR

jGROUP 2

3

Nickel-copper alloys Copper-nickel alloys Tin bronze Gun metals Valve bronze

Inspector's Eandbook

S-35, S-36

S-42, S-43. S-44

7-20


-

-


2% Penetrameter Quality Conversion Chart (X-RAY ONLY)


7-23


Basic Components of an Xray Tube

Highvoltage Power supply

Cathode Struc

Lowvoltage power supply

I / '

Filament 87

I/

Electron

,

7

Focusing cup X-ray beam

1

\

Tube envelope

Types of Scatter Radiation

Test piece

L

(a) Internal scatter

-

(b) Side

scatter


-

(c) Back scatter

Radiographic Film Interpretation Arc strikes DEFINITION: Any localized heat-affected zone or change in the contour of the surface of the furished weld or adjacent base metal resulting from .anarc or heat generated by the passage of electrical energy between the surface of the finished weld, base material and a current source, such as welding electrodes or magnetic particle inspection electrodes.

4

RADIOGRAPHIC APPEARANCE: A localized area, rounded or irregular, and generally found adjacent to the edge of the weld image on the base metal. The density of the indication appears lighter when the discontinuity is convex from the addition of filler metal with arc strikes resulting from SMAW process. The density of the indication appears darker when the discontinuity is concave resulting from a gouging of the material with arc strikes resulting from the GTAW or SMAW processes. CAUSES: Not initiating the arc as required by the welding procedure. Accidentally striking an arc on the completed weld or base material. Engaging the magnetizing current prior to establishing fmcontact with the test surface when using prods. Moving or removing the prods from the test surface without disengaging the magnetizing current. REMARKS/SPECIAL CONSIDERATIONS: Arc strikes from welding and MT are generally revealed and dispositioned upon acceptance Visual inspection. However, welding arc strikes may occur from another welding operation in the area after the VTPT inspectior and prior to the RT. Arc strikes occurring in this sequence have a random location and can be found on the we. well as on the base metal. Arc strikes fiomMT will be difficult to detect by RT. Visual inspection should always be performed to confirm arc strikes.


Y

Burn through DEFINITION: A A. void or open hole extending - into a backing - ring or strip, fused oot or acliacent b&e metal.

IXAULWKAYHIC APPEARANCE: m irregular localized area of darker density, often rounded, gmerdlly found at the center of the weld image. If excessive globules of the weld puddle resulting from the burn through, are present on the inside of the weld joint, their appearance will have a lighter density due to the additional weld metal. The nature of burn through is such that the i may or may not be sharply defined. s edges of the in CAUSE;u.

Using a weld c:urrent higher than allowed by the welding procedure. 'Improyjerly preparing the tungsten electrode tip. d of travel will cause overheating of the Using too slour a weldp weld putIdle. - -Improper n r --up of the wela jomt (unacceptable root gap). t

- -

.

.

C L

-

ECIAL ( IERATIONS: u ~ s ~ ~ l ~ ~fea~urt; s h i nU GgL ~ X I I a burn through and a melt through is that a burn through results in an open hole on the ID of the pipe. Burn through most often occur during the welding of the root pass, although it is possible for this discontinuity to be introduced during the welding of the second layer. I L Burn through frequently occur during weld repairs, especially when the repair cavity is at the root depth. Visual inspection should always be performed, if possible, to confirm bum through. I 11G


7-27

Concavity I-ION: RADIOGRAPHIC APPEARANCE: CAUSE! REMARKS/SPECIAL CONSIDERATIONS:

7-28


Crack crater

DEFINITION: A linear rupture of metal under stress.

b

,

~ ~~IRANCE: o ~ ~ ~ ~ Generally a star shaped indication with irregular, feathery?twisting lines of darker density oriented within a weld crater. The discontinuity is usually shallow, therefore, the indication may not be as pronounced as indications ~UUU from ~G other C .types I of cracking. CAUSES:

' Impr01

)f the welding arc by abruptly removing the arc. meters of the welding procedure. Not ad - incomplete fillmg 01 ule weld crater.

4

4B

T

IREMAP 2ONSIDERATIONS: hasized that although the discontinuity and resulting radiographic indication is generally star It is to be emp shaped, crater cracking does not always take this shape. -- Random raaographic indications from crater cracking may be oriented in any direction to the weld axis. .-.

3:


7-29

Crack, longitudinal (shown in the root)

DEFINITION: A linear rupture of metal under stress. RADIOGRAPHIC APPEARANCE: Irregularly shaped, feathery, twisting lines of darker density oriented along the axis of the weld. CAUSES: Improper fit-up of joint. Contamination of base material. Violation of the welding procedures. REMARKS/SPECIAL CONSIDERATIONS: Longitudinal cracks can occur throughout the weld; in the centerline, fusion lines and in the root. Cracking can, at times, be difficult to detect due to the geometric principles of the radiographic technique.

Crack, transverse DEFINITION: A linear rwture of metal under stress. u &IDIOGRAPHIC APPEARANCE: Irregularly shaped, feathery, twisting lines of darker density oriented perpendicular to the axis of the weld. Transverse cracks are generally tight discontinuities, therefore producing subtle indications on the radiograph. CAUSES: Transverse cracks are generally the result of longitudinal shrinkage strains acting on weld metal of low ductility. Most commonly found in weld joints having a high degree of restraint. REMARKSISPECIAL CONSIDERATIONS: Cracks may be limited in size and completely within the weld metal, but may also propagate fiom the weld metal into the adjacent heat affected zone. Orientation and subtleness of the discontinuity can, at times, be difficult to detect due to the geometric principles of the radiographic technique. Cracking indications can be masked in the as-welded condition.

\v


7-31

Crater pits

DEFINITION: An approximately circular surface condition extending into the weld in an irregular manner. e

RADIOGRAPHIC APPEARANCE: %e indication will appear as a circular dot with darker density, similar to porosity, in the root area of lble insert welds. However, due to the irregular nature of discontinuity, the edge of the indication is usually I~UL a5 uefined as porosity. The irregularity of the discontintinuity can produce a "halo" effect on the edge of the indicatia~n,distinguishing a crater pit fiom porosity. The radiographic indication from crater pits can range fiom subtle to pronomnced, depending on the severity of the pit. I

CAUSES: Impr01per tennination of the welding arc. lhering to the parameters of the welding procedure. REMARKSISPECLAL CONSIDERATIONS: The in s from crater pits can be misinterpreted as porosity. Porosi ccur anywhere in the weld, while crater pits occur in the weld root area. - xr:--.-1 v.l q 1 1 n ~mspecrion should always performed, if possible to confirm crater pits. * Additional radiography, e.g. putting the indication in the sidewall or profile view, may be employed to assist in confiinn;ation of the discontinuity. A " -

7-32


Incomplete fusion of a consumable insert DEFINITION: Tncompletemelting of the consumable insert without fusion and bonding to the base metal along one or F :s of the consumable insert. \c/ RADIOGRAPHIC APPEARANCE: I i unifomn elonge~tedband or localized bad of lighter density in the center of the weld image, oriented along 1he axis of the weld. The width of the band appears approximately equal to the diameter of the consumable insert. I

L

The indication nlay appear in the following ways -- . The indcation rnav aDpear with both edges straight with abrupt density transitions fiom the insert area to the base Imaterial area. TI rites lack of filling or blending to the base metal, with both sides of the insert not fused. The indication pear with one edge having a smooth,gradual density transition fiom the insert area to the base material area and the other edge straight with an abrupt density transition fiom the insert area to the base material area. lllis indicates the former edge is blended with firsion into the adjacent base metal and the latter edge is not fused. I

CAUSES: Impro!~ f iUPt of the weld joint. Using too low a welding current. Using too fast of a travel speed. An incorrect torch angle. An improper motion or weaving technique of the torch. ,

REMARKS/SPECIAL CONSIDERATIONS: Visual inspection should always be performed, where possible, to confirm incomplete fusion of the insert, when viewed on radiographs.

b8


Lack of fusion DEFINITION: Lack of complete fusion of some portion of the metal in a weld joint with the adjacent metal. The adjacent metal may be either base metal or previously deposited weld metal. When the discontinuity occurs between a weld bead and the adjacent base metal, the term "lack of sidewall h i o n " is often used, does not occur in the root. RADIOGRAPHIC APPEARANCE: Irregularly edged, or straight and irregularly edged lines of darker density oriented along the axis of the weld. If lack 6f fusion occurs between weld beads, both edges of the indication may be irregular as they indicate the weld puddle not fusing to the contour of the previously deposited weld beads. If the lack of fusion occurs between a weld bead and base metal, one edge of the indication will be straight, as it indicates the weld puddle not fusing to the prepared base meal. Sometimes the lines are interspersed with darker density spots, of varying shapes, indicating voids resulting from the lack of fusion. CAUSES: mcient welding current to melt the adjacent metal. Too fast a welding speed of travel will not allow for fusion to the adjacent metal. Too fast a welding current to melt the adjacent metal. Improper torch or electrode angle may prohibit melting of the adjacent metal. . Improper placement of weld passes may cause a sharp valley to fonn. Lack of proper access to the face of weld joint. Tightly adhering oxides resulting from improper cleaning of items to be welded. REMARKS/SPECIAL CONSIDERATIONS: Lack of fusion on the under bead side of the weld, lying in a horizontal plane, tends to be undetectable but often the sides of lack of fusion lines tend to curl out of the horizontal plane and are recorded on the radiograph. - A distinguishing characteristic between lack of fusion and incomplete penetration is that lack of h i o n can occur anywhere in the weld and incomplete penetration occurs at the weld root.


Lack of penetration (left - nonnal fit-up, right - mismatch) DEFINITION: Lack of penetration of the weld through the thickness of the joint or penetration which is less than kspecified.

GRAPHIC APPEARANCE: Straight, fine edged lines of darker density oriented along the axis of the weld in the area of the root. The straightrless of both edges of the indication's image and location in the center of the weld image help to distinguish incomplete penetration from lack of fusion. CAUSE Insuff

-

elding current or to fast travel speed.

-Irnnroya wren or electrode angle to melt the root land. r-I----

In both backing ring joints and joints to be welded from both sides, improper placement of initial weld pass may cause a sharp valley to form at the root weld. from both sides, insufficient removal of the backside prior to welding. Joints

REMARKSISPECIAL CONSIDERATIONS: weld roc~tand is always straight, as it is a RT indication of the actual weld joint preparation. The s atthe7 on can be prominent or subtle depending on the severity of the discontinuity.


7-35

Melt through

.-

DEFINITION: A convex or concave irregularity on the s&ce of a backing ring or strip, fbsed root or adjacent base metal resulting from fusing comple through a localized region but without development of a void or open hole. RADIOGRAPHIC APPEARANCE: A localized area, usually rounded, and generally found at the center of the weld image. The density of the indication appears lighter when the discontinuity is convex and darker when the discontinuity is concave. CAUSES: Using a weld current higher than allowed by the welding procedure. Improperly preparing the tungsten electrode tip. Using too slow a welding speed of travel will cause overheating. Improper fit up of the weld joint (unacceptable root gap). REMARKS/SPECIAL, CONSIDERATIONS: The entire thickness of metal is melted or re-melted and deforms, m hole or void develops as with a burn through. Melt through most often occurs during the welding of the root pass, although it is possible for this discontinuity to be introduced during the welding of the second layer. Visual inspection should always be performed, if possible, to confirm melt through.


u

Offset (misalignment/rnismatch,shown with LOP) DEFINITION: Lateral misalignment of two butt joint members of equal 'L thickness.

RADIOGRAPHIC APPEARANCE: Offset on piping weld joints can appear on the film in different ways. The radiographic image is dependent upon the orientation of the offset to the beam of radiation. When the offset condition is parallel to the beam of radiation, the offset image may appear as an abrupt density change, generally half m y across the width of the weld image. When the offset condition is perpendicular to the beam of radiation, and the entire image of the item is on the film, the offset image will appear in the sidewall or profile view, as lateral misalignment of the members with a high-low effect of the pipes' ID and OD. CAUSES: Improper fit-up or fixturing may cause the members to be offset. Improper welding block sequencing on the root pass. REMARKSISPECIAL CONSIDERATIONS: Visual inspection should always be performed to c o n f i i questionable offset conditions when viewed on radiographs.


7-37

Oxidation

DEFINITION: A condition resulting from partial or complete lack of purge of a surface which is heated during weldiv u resulting in formation of oxide on the surface. This condition may range from slight oxidation through the formation of heavy black scale to the extreme of a very rough surface having a rough crystalline appearance.

OGRAPHIC APPEARANCE: Highly irregular, low density area, with a wrinkled or sugared appearance in the center of the weld image. The condition may extend for the entire circumference of the weld when there is a complete loss of purge. The condition may only be localized, in one or more areas of the weld, occurring whenever the purge is partially interrupted. CAUSES: *,Loss of internal purge gas resulting in an unshielded molten weld puddle on the ID. High oxygen content in purge gas or path. Moisture in the area of the weld, due to inadequate drying of the purge path, leakage, etc... REMARKSISPECIAL CONSIDERATIONS: A visual inspection should always be performed, if possible, to confirm oxidation. Oxidation generally occurs during the flowing of the weld root. However, this condition may occur during welding if there is a degree of root reflow, loss of purge, or moisture present. Oxidation frequently occurs during weld repairs.

Overlap (re-entrant angle) DEFINITION: The protrusion of weld metal beyond the weld toes or weld root. " , ~ I O G R A P H I C APPEARANCE: 3verlap conditions on the OD of piping butt weld joints should be an extremely m e occurrence in as much ;factory VT and other surface inspections, such as PT or MT are required prior to RT. However, overlap i on ult: mternal weld surface consumable insert piping weld butt joints can appear on the film in different ways. The phic im2ige is dependent upon the orientation of the overlap to the beam of radiation. When the overlap I r is not ;located in the sidewall or profile view, the overlap image will appear consistent with that of -..&+L . C u l ~ v c n l r vW I U ~ an abrunt density change at the fusion line of the weld root image. When the offset image is in the !sidewall or profile view, it will appear as roll over of the weld root reinforcement with an unsatisfactory blending iat the fu:sion line:ofthe\weld root image. d

I

-

-

I

S: ow of a welding speed. .roo low or too hi& of a welding current. ect torchI or eleclM e angle.

-

REMARKSISPECIAL CONSIDERATIONS: Visual inspection should always be performed, where possible, to confm questionable root surface conditions when viewed on radiographs.

Inspector's Harrdbook

7-39

Porosity (right - clustered porosity, bottom left - distributed porosity, bottom right aligned porosity in the root)

-

DEFJNITION: Gas pockets or voids in weld metal.

RADIOGRAPHIC APPEARANCE: Usually spherically shaped areas of darker density and may be scattered throughout single pass welds or throughout several passes of multiple pass welds. Although usually spherical in shape, porosity may also occur as nonspherical pockets and appear on the radiograph as elongated voids, sometimes referred to as "piping or wormhole porosity". The density of the indication varies directly with the diameter or magnitude of the pore. CAUSES: Faulty welding techniques such as using too long an arc with the SMAW process. Improper cleaning of the weld joint.

REMARKSISPECIAL CONSIDERATIONS: None.


Root razorback condition DEFINITION: An oxide membrane, gray in color, with a sharp ridge or peak and ribs fi.om the peak to the edge giving it a 'ierringbone effect. Also known as "reverse center line crease."

L

RADIOGRAPHIC APPEARANCE: The image of root razorback is consistent with that of convexity with an associated herringbone appearance and sharp peak at the center. The lightest density of the image is in the center and is dependent upon the height of peaked condition. The density of the image gradually increases as the condition blends into the base metal. CAUSES: Moisture in the area of the weld. Moisture in the purge gas. REMARKSISPECIAL CONSIDERATIONS: This is one of the most common root surface defects encountered when welding NiCu and Ni-C-r-Fe. Visual inspection should always be performed, where possible, to confm root razorback condition when viewed on radiographs.


Root surface centerline crease DEFINITION: An intermittent or continuous peripheral centerline concavity fonned on the root surface. I

RADIOGRAPHIC APPEARANCE: The image of centerline crease is consistent with that of concavity with an associated herringbone appearance. If the crease has a notch or a questionable blending condition at the center, the image will crease oriented along the axis of the weld. CAUSES: Thick cover pass over a consumable insert that had minor concavity. Excessive welding current. REMARKSISPECIAL CONSIDERATIONS: Visual inspection should always be preformed, where possible to confm questionable centerline crease when viewed on radiograph. Approved workmanship sample radiographs may be employed to evaluate centerline crease when a visual inspection is not possible.

Inspector9s Handbook

4

Root surface concavity DEFINITION: A depression on the root surface of the weld, which may be due to -pvity, internal purge or shrinkage. L/ RADIOGRAPHIC APPEARANCE: The image of concavity may appear as intermittent elliptical areas or elongated bands of darker film density oriented along the axis of the weld in the center of the weld image. The width of the image is consistent with the weld root width. The darkest density of the concavity's image is generally in the center and is dependent up6n the depth of the concavity. The density of the image gradually decreases as the concavity blends into the base metal. .

CAUSES: Improper fit up of the weld joint. Using too high of a'welding current, too slow of a travel speed, or extremely high purge gas flow rate. REMARKSISPECIAL CONSIDERATIONS: Visual inspection should always be preformed, where possible to confirm questionable concavity when viewed on radiograph.


7-43

Root surface convexity

I

TION: Reinforcement of tk root surface of a butt- ksed type weld.

I

4

RADIOGRAPHIC APPEARANCE: The image of convexity may appear as intermittent elliptical areas or elongated bands of lighter film density oriented along the axis of the weld in the center of the weld image. The widthof the image is consistent with the weld root width. The lightest density of the convexity's image is generally in the center and is dependent upon the height of the convexity blends into the base metal. CAUSES: Using to low or high of a welding currert. Using too slow travel speed when welding. REMARKS/SPECIAL CONSIDERATIONS: Visual inspection should always be performed, when possible, to confirm questionable convexity when viewed on radiographs.

Slag,

DEFINITION: Non-metallic solid material entrapped in weld metal or b'ptween weld metal and base metal. .2 RADIOGRAPHIC APPEARANCE: Well defined, irregularly shaped, uniformly darker density areas usually elongated along the axis of the weld. (

unproper 111-up, - sucn as maequate bevel of the joint sides. Using too low a weldinkg currer~tfor the size of electrode. Faulty welding: techniques sucl1 as wrong electrode position or orientatic3n. I bead placemtznt causing sharp valleys or undercutting 'Impr01nx +La L , , 1between is. slag from the surface. mpro]per interpass clel

-

.---,--REMARKSISY~CIAL CUNSIOERATIONS: Slag isr a byproduct of 'the bur^ning of the flux covering on welding OnS are iasociated with the SMAW process. roods. Thus, slagg inclusi~ -. . .-...I+ull~rlghoutthe weld, in the center of the Slag hlulw~v~la w -UJ welcl-in fusion lines and in the r&t. . . . , a

a , . ,

...

'v

Inspectds Handbook

Tungsten inclusion

DEFINITION: Metallic tungsten inclusions in the weld deposit. RADIOGRAPHIC APPEARANCE: Irregularly shaped spots of low film density areas, usually random in size and location. They are solid or liquid bits of tungsten electrode from the TIG welding process that drop or are melted from the electrode and become entrapped in the weld puddle. Tungsten inclusions appear as low or light density areas on the radiograph because of the differences of radiographic absorption between the inclusion and is dnwr radi6graphically then the surrounding metal. surrounding metal and therefore absorbs more radiation. This, in turn, allows fewer rays to reach the film.

sten en

CAUSES: Overheating the tungsten electrode due to excessive current for the particular electrode size. DpfPctive tungsten electrode (flaking of particles). --*m Dipping the tungsten into the molten puddle. REMARKSISPECIAL CONSIDERATIONS: None.

Undercut DEFINITION: .An tl intermittent or continuous groove on the external surface of he base Imetal along the edge of the weld.

51

k A u l u G W H l c MY~ARANCE: a irregular, elongated area of darker density oriented along the extamdl h i o n line of the weld image to the base metal. cxccsslve welding current. using too long an arc length will result in a gouging effect. I8 using excessiv,e welding speed of travel. . w nen uslng me GTAW process, adding an -cient amount of filler me ectrode angle can cause a gouging effect. An inc t

.'a

rrn

REMARKS/SPECIAL CONSIDERATIONS: External undercut is readily revealed and dispositioned upon acceptarice Visu inspec:tion. Visuali inspect:ion shouId always be performed to confirm questionable . extema unaercut wnen viewed on radiographs.

.

-


7-47

-

Undercut, root

DEFINITION: An intennittent or continuous groove in the internal surface of the base metal, backing ring/strip along the edge of the root of the weld. )GRAPHIC APPEARANCE: An irregular, elongated area of darker density oriented along the lnternai h i o n line of the weld image to the base metal. mproper la up of the weld joint. Excessive current during welding When using the GTAW process, adding an insufficient amount of incorrect electrode angle can cause a gouging effect. filler m KEMARKS/SPECIAL CONSIDERATIONS:

Radic based .. c

7-48

evaluation of root undercut in backing ring joints can be nanship sample radiographs as well as the use of slotted

ImyectoISs Handbook

Weld splatter

.

DEFINITION: In arc welding, the metal particles expelled during welding which do not form a part of the weld. iL/ ,

RADIOGRAPHIC APPEARANCE: Small, rounded areas of lighter density generally found adjacent to the edge of the weld image on the base metal. CAUSES: There will be some weld spatter when using the SMAW process. However, long arcing is a factor. Lack of concentricity or damage to the electrode flux. REMARKS/SPECIAL CONSIDERATIONS: Weld splatter is most commonly found when the SMAW welding process is employed. Weld spatter is generally revealed and dispositioned upon acceptance Visual inspection. However, weld spatter may occur from another welding operation in the area after the acceptance VTPT inspections and prior to the RT.


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