DERRICK CONSTRUCTION BEFORE WE GO FURTHER TO UNDERSTAND WHAT IS BOLT TORQUE AND BOLT CHECK, LET’S FIND OUT, WHAT IS BOLT ASTM A325 & ASTM A490 AND DERRICK CONSTRUCTION?
BOLT ASTM A325 ASTM (AMERICAN SOCIETY FOR TESTING AND MATERIALS) ASTM A325 IS STANDARD FOR HEAVY HEX STRUCTURAL BOLT WHICH HAVE 830 Mpa MINIMUM TENSILE STRENGHT AND HAVE RANGE FROM M12 ~ M36
ASTM A325 IS SIMILAR TO BOLT GRADE 8.8
BOLT ASTM A325 IMPERIAL SYSTEM ASTM A325 MINIMUM TENSILE STRENGTH = 120/105 KSI SIZE RANGE = 1/2“ – 1-1/2” METRIC SYSTEM ASTM A325 MINIMUM TENSILE STRENGTH = 830 Mpa SIZE RANGE = M12 – M36
IMPERIAL SYSTEM = BRITISH METRIC SYSTEM = AMERICA
BOLT ASTM A490 ASTM (AMERICAN SOCIETY FOR TESTING AND MATERIALS) ASTM A490 IS A STANDARD FOR HEAVY HEX STRUCTURAL BOLT MADE FROM ALLOY WHICH HAVE 1040 MPA MIN. YIELD STRENGTH AND HAVE RANGE FROM M12 ~ M36
ASTM A490 IS SIMILAR TO BOLT GRADE 10.9
BOLT ASTM A490 IMPERIAL SYSTEM ASTM A490 MINIMUM TENSILE STRENGTH = 150 – 173 KSI SIZE RANGE = 1/2“ – 1-1/2” METRIC SYSTEM ASTM A490 MINIMUM TENSILE STRENGTH = 1040 Mpa SIZE RANGE = M12 – M36
IMPERIAL SYSTEM = BRITISH METRIC SYSTEM = AMERICA
DERRICK STRUCTURE What is derrick structure? A TALL FRAMEWORK ERECTED OVER AN OIL WELL AND USED TO SUPPORT HOISTING EQUIPMENT (FOR RAISING & LOWERING)
BASIC CONCEPT BOLTED STRUCTURE
STRESS AREA = SHARE LOADS
The structure will have slightly movement on its load path and then the bolts will act as stabilizer and to hold the structure.
BASIC CONCEPT BOLTED STRUCTURE Reference API RP 4G. “Each part of a bolted structure is designed to carry its share of the load. Parts omitted or improperly placed may contribute to the failure of the structure” (5.3.1) “During erection of bolted structures, bolts should be left loose enough, in way of erection, to allow proper fit of adjacent mast/derrick members without distortion and locked in stress” (5.3.1)
Reference AISC 13 The snug-tightened condition is the tightness that is attained with a few impacts of an impact wrench or the full effort of an ironworker using an ordinary spud wrench to bring the connected plies into firm contact” (8.1)
CONCLUSION
CONCLUSION 1. DERRICK IS A TALL ERECTED STRUCTURE TO CARRY STATIC LOADS 2. BOLTS ON DERRICK HELP TO MINIMIZE PREMATURE FAILURE (FRACTURE / CRACKS) ON STRUCTURE DUE TO SHARE LOADS (MULTIPLE AXIS FORCE) 3. TENSILE STRENGHT ON BOLTS WILL HELP THE BOLTS TO SUSTAIN THE GIVEN SHARE LOADS 4. THE PRE-TENSION BOLTS SHOULD BE LEFT LOOSE ENOUGH TO ALLOW FIT ADJACEMENT WITHOUT DISTORTION AND LOCKED IN STRESS 5. BOLT GRIP STRENGHT SHOULD FREQUENTLY CHECK OR TORQUE AS PER MANUFACTURE OR SPEC RECOMMENDATION
BOLT TORQUE
TAP CHECK
Definition:
Definition:
To return the bolt to their original value based on its yield strength by using calibrated wrench
To check the in-service bolt by using ordinary spudwrench and impacts to desired minimum tension
Torque value known
Torque value unknown
AISC
RCSC
(American Institute of Steel Construction)
(Research Council on Structural Connection)
ASSEMBLY CONTRACT DOCUMENT
B. SNUG TIGHTENED JOINT (Prior to the start of work)
THE BOLTS SHOULD NOT BE INSPECTED TO DETERMINE THE ACTUAL INSTALLED PRETENSION (AISC 9.1)
A. PRETENSIONED JOINTS (Prior to the start of work)
Turn-of-nut method
Calibrated wrench method
Twist-of-type method
Direct-tensionindicator
Manufacturer / Engineer approval
(AISC section 9.2.1)
(AISC section 9.2.2)
(AISC section 9.2.3)
(AISC section 9.2.4)
(AISC section 2.6.2)
BOLT TORQUE
TAP CHECK
Recommendation reference:
Recommendation reference:
“At completion of erection, all bolts should be checked for proper torque. Periodically, all bolts should be checked for proper torque”
For joints that are designated in the contract documents as snug-tightened joints, the bolts shall be installed in accordance with Section 8.1 ( Snug-Tightened Joints). For joints that are designated in the contract documents as pre-tensioned or slip-critical, the bolts shall be installed in
(AP RP 4G, section 5.3.1)
“Bolt tensioning shall be achieved using calibrated tensioning methods. Bolts that are specified to be pretensioned to a higher value than 50 % of the bolt material minimum ultimate strength shall only be used once
The use of the turn-of-nut method is always acceptable for use on bolts which are not to be reused. Reuse of bolts is
B. SNUG TIGHTENED JOINT
acceptable if so specified in the manufacturer’s instructions or by a professional engineer
(Prior to the start of work)
THE BOLTS SHOULD NOT BE INSPECTED TO DETERMINE THE ACTUAL INSTALLED PRETENSION
(AP RP 4G, section 5.3.1)
(AISC 9.1)
Check 10% of the bolts at the connections on torque by a calibrated torque wrench. If some bolts are not on the correct pre-stress, then check the complete connection. Put the bolts again to the correct pre-stress by a calibrated torque wrench (NOV Derrick manual No: T7801-Z-MA-001 section 6.3.3)
A. PRETENSIONED JOINTS (Prior to the start of work)
Turn-of-nut method (AISCsection 9.2.1)
Calibratedwrench method
Twist-of-type method
Direct-tensionindicator
Manufacturer / Engineer approval
(AISCsection9.2.2)
(AISCsection9.2.3)
(AISCsection9.2.4)
(AISCsection2.6.2)
BOLT TORQUE To return the bolt grip value by using calibrated torque wrench by applying a calculated average torque value to fasteners.
TAP CHECK Turn-of-nut is performed by rotating the nut or bolt of a fastener assembly a specific turn angle based on the fastener's length, and diameter while restraining the unturned element from rotating
Torque value refer to manufacture recommendation Manufacture recommendation NO derrick
Table 1 for turn-of-nut pre-tensioning
Hot Dip Galvanized
Size M20
8.8
Phosphate 412 Nm
10.
Bolt length
Bolt face normal to bolt axis
Tolerance
< 4d
1/3 turn
±30 Deg
< 4d > 8d
1/2 turn
±30 Deg
< 8d > 12d
2/3 turn
±40 Deg
465 Nm
9
M22
8.8
554 Nm
10.
626 Nm
9
M24
8.8
712 Nm
10.
804 Nm
9
M27
8.8
1028 Nm
10.
1161 Nm
9
M30
8.8
1402 Nm
10.
1582 Nm
9
REMEMBER!! ASTM A325 IS SIMILAR TO BOLT GRADE 8.8 ASTM A490 IS SIMILAR TO BOLT GRADE 10.9
BOLT TORQUE
TAP CHECK
Match mark: Match-marking is a drawn line from nut to the extend bolt thread of base metal and this is to improve the ability to inspect bolts that have been pre-tensioned with the calibrated torque wrench method
Before torque
After torque
Match-mark
BOLT TAP CHECK
Step 1. Fit the flogger to size nut
Step 2. Apply few impact on flogger until visually the nuts firm (tight) to the surface Step 2. Spray and draw a match-mark on bolt and nut for next survey
BOLT TORQUE
BOLT TORQUE
Step 1. Check the torque value from derrick drawing & set the torque value on wrench Step 2. Torqueing bolt on derrick. Follow step and manual of torque wrench Step 3. Spray and draw a match-mark on bolt and nut for next survey
THANK YOU REFERENCE - American Institute of Steel Construction (AISC) 13th edition - Research Council on Structural Connections (RCSC) - API RP 4G Operation, Inspection, Maintenance, and Repair of Drilling and Well Servicing Structures - Derrick NOV manufacturer manual Question??
