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API 570
PIPING INSPECTION CODE: In-service Inspection Rating Repair Alteration of Piping Piping Systems Systems
API 570
PIPING INSPECTION CODE: In-service Inspection Rating Repair Alteration of Piping Piping Systems Systems
API 570 SCOPE TERMS & DEFINITIONS INSPECTION PLANS
INTERVAL / FREQUENCY & EXTENT OF INSPECTION INSPECTION DATA EVALUATION, ANALYSIS & RECORDING
API 570 S C O P E COVERS INSPECTION. INSPECTION. . . RATING, REPAIR, ALTERATION PROCEDURES FOR METALLIC & FIBERGLASS REINFORCED PLASTIC (FRP) PIPING SYSTEMS S YSTEMS AND THEIR ASSOCIATED ASSOCIATED PRESSURE PRE SSURE RELIEVING DEVICES THA TH AT HAVE HAVE BEEN PLACED INSERVICE
API 570 S C O P E - INTENT
Specify the in-service inspection and condition-monitoring program that is needed to determine the integrity of piping.
API 570 SCOPE - INCLUDED FLUID SERVICES
APPLIES TO PIPING SYSTEMS FOR: • PROCESS FLUIDS • HYDROCARBONS • SIMILAR FLAMABLE OR TOXIC FLUID SERVICES
API 570
SCOPE
OPTIONAL PIPING SYSTEMS & FLUID SERVICES
API 570 SCOPE - FITNESS FOR SERVICE & RISK BASED INSPECTION (RBI) API 579 Provides detailed assessment procedures for specific types of damage that are referenced in this code.
The inspection code recognizes RBI concepts for determining inspection intervals.
API 580 provides guidelines for conducting a risk based assessment.
API 570 TERMS & DEFINITIONS
Authorized Piping Inspector : is an employee of an authorized inspection agency who is qualified and certified to perform the function
specified in API 570. An NDE examiner is not required to be an authorized piping inspector
API 570 TERMS & DEFINITIONS Condition Monitoring Locations CMLs: Designated areas on piping systems where periodic examinations are conducted
Corrosion Rate: The rate of metal loss due to erosion erosion/corrosion or the chemical reaction(s) with the environment, either internal and /or external.
API 570 TERMS & DEFINITIONS Damage Mechanism: Any type of deterioration that can affect the integrity of piping (e.g. corrosion, cracking, erosion, dents, and other mechanical, physical or chemical impacts). See API 571 for a comprehensive list and description of damage mechanisms.
Deadlegs: Components of piping system that normally have no
significant flow.
API 570 TERMS & DEFINITIONS External Inspection: A visual inspection performed from the outside of a piping system to find conditions that could impact the piping systems’ ability to maintain pressure integrity or conditions that compromise the integrity of the coating and insulation covering, the supporting structures and attachments
Fitness For Service Evaluation: A methodology whereby flaws and
other deterioration/damage contained within piping systems are assessed in order to determine the structural integrity of the piping for c ontinued service.
API 570 TERMS & DEFINITIONS General Corrosion: Corrosion that is distributed more or less uniformly over the surface of the piping, as opposed to being localized in nature.
In Service Inspection: All inspection activities associated with piping after it has been initially placed in service
Inspection: The external, internal, or on-stream evaluation (or any combination of the three) of piping condition conducted by the authorized inspector or his/her designee.
API 570 TERMS & DEFINITIONS Inspection Plan: A documented plan for detailing the scope, methods and timing of the inspection activities for piping systems, which may include
recommended repair, and/or maintenance. Localized Corrosion: Deterioration, e.g. corrosion that is confined to a limited area of the metal surface. Maximum Allowable Working Pressure (MAWP): The maximum internal pressure permitted in the piping system for continued operation at
the most severe condition of coincident internal or external pressure and temperature (minimum or maximum) expected during service.
API 570 TERMS & DEFINITIONS Minimum Required Thickness: The thickness without corrosion allowance for each component of a piping system based on the appropriate design code calculations and code allowable stress that consider pressure, mechanical and structural loadings.
On Stream Inspection: An inspection performed from the outside of piping systems while they are on-stream using NDE procedures to establish the suitability of the pressure boundary for continued operation.
API 570 TERMS & DEFINITIONS Risk Based Inspection (RBI): A risk assessment and risk management process that is focused on inspection planning for piping systems for loss of containment in processing facilities, which considers both the probability of failure and consequence of failure due to material deterioration.
Soil-To-Air Interface: An area in which external corrosion may occur on partially buried pipe.
API 570
TERMS & DEFINITIONS
Structural Minimum Thickness: Minimum thickness without corrosion allowance, based on structural and other loadings.
API 570 INSPECTION PLANS Development of an Inspection Plan
An inspection plan shall be established for all piping systems within the scope of this code. The inspection plan is developed from the analysis of several sources of
data.
API 570 INSPECTION PLANS Minimum Contents of an Inspection Plan
Define the type(s) of inspection needed, e.g. internal, external, on-stream Identify the next inspection date for each inspection type Describe the inspection methods and NDE techniques Describe the extent and locations of inspection and NDE at CMLs
API 570
RBI
RBI can be used to determine inspection intervals and the type and extent of future inspection/examinations.
API 570 RBI
Probability Assessment
The probability assessment shall be in accordance with API 580 and shall be based on all forms of damage that could reasonably be expected to affect equipment in any particular service.
API 570
RBI
Consequence Assessment
The consequence of a release is dependent on type and amount of
process fluid contained in the equipment
API 570 RBI Frequency of RBI Assessment The assessment shall be updated after each equipment inspection as
defined in API 580. The RBI assessment shall also be updated each time process or hardware changes are made or after any event occurs that could significantly affect damage rates or damage mechanisms.
API 570
INSPECTION PLANS
Inspection for Types & Locations of Damage Modes of Deterioration & Failure
API 570
INSPECTION PLANS
Equipment Damage Types
Damage Type
Damage Mechanism
General and local metal loss
Sulfidation Oxidation Microbiologically influenced corrosion Organic acid corrosion Erosion/erosion-corrosion Galvanic corrosion CUI
Surface connected cracking
Fatigue Caustic stress corrosion cracking Sulfide stress cracking Chloride stress corrosion cracking Polythionic acid stress corrosion cracking Other forms of environmental cracking
Subsurface cracking
Hydrogen induced cracking
Metallurgical changes
Graphitization Temper embrittlement
Blistering
Hydrogen blistering
Material properties changes
Brittle fracture
NOTE API 571 has a much more complete listing and description of damage mechanisms experienced in the refining and petrochemical industry.
API 570 INSPECTION PLANS Areas of Deterioration For Piping Systems Injection points and mix points Deadlegs
CUI Soil to Air Interfaces Service Specific & Localized Corrosion Erosion, Corrosion, & Erosion/Corrosion Fatigue Cracking
INSPECTION PLANS General Types of Inspection & Surveillance
Internal Visual Inspection On-Stream Inspection Thickness Measurement Inspection
External Visual Inspection CUI Inspection Vibrating Piping Inspection Supplemental Inspection Injection Point Inspection
API 570
API 570 INSPECTION PLANS CMLs CMLs are specific areas along the piping circuit where inspections are to be made. The minimum thickness at each CML can be located by ultrasonic scanning or radiography. The rate of corrosion/ damage shall be determined from successive measurements and the next inspection interval appropriately established. CMLs should be marked on inspection drawings and on the piping system to allow repetitive measurements at the same CMLs. This recording procedure provides data for more accurate corrosion rate determination. Careful identification of CMLs and examination points are necessary to enhance the accuracy and repeatability of the data.
API 570 INSPECTION PLANS
Condition Monitoring Methods UT and RT
As a general rule, each of the NDE techniques will have practical limits with
respect to accuracy .
API 570 INSPECTION PLANS Other NDE Techniques for Piping Systems Magnetic Particle Liquid Penetrant Flux Leakage Eddy Current Acoustic Emission Thermography Long Range UT (GUL – Guided Ultrasonic Longwave)
API 570 INTERVAL / FREQUENCY & EXTENT OF INSPECTION
General To ensure equipment integrity, all piping systems and pressure-relieving devices shall be inspected at the intervals/ frequencies provided in this section.
API 570 INTERVAL / FREQUENCY & EXTENT OF INSPECTION Inspection Intervals If RBI is not being used, the interval between piping inspections shall be established and maintained using the following criteria: Corrosion rate and remaining life calculations Piping service classification Applicable jurisdictional requirements Based on operating conditions, previous inspection history, current inspection results, and conditions that may warrant supplemental inspections.
API 570 INTERVAL / FREQUENCY & EXTENT OF INSPECTION Inspection Intervals The owner/user or the inspector shall establish inspection intervals for thickness measurements and external visual inspections and, where applicable, for internal and supplemental inspections.
Thickness measurements should be scheduled at intervals that do not exceed the lesser of one half the remaining life determined from corrosion rates indicated or the maximum intervals recommended in Table 2. Shorter intervals may be appropriate under certain circumstances.
API 570 INTERVAL / FREQUENCY & EXTENT OF INSPECTION
Piping Service Classes
All process piping systems shall be categorized into different piping classes.
API 570 INTERVAL / FREQUENCY & EXTENT OF INSPECTION Class 1 Services with the highest potential of resulting in an immediate emergency if a leak were to occur are in Class 1.
Class 2
Services not included in other classes are in Class 2. This classification includes the majority of unit process piping and selected off-site piping.
Class 3 Services that are flammable but do not significantly vaporize when they leak and are not located in high-activity areas.
Class 4 Services that are essentially nonflammable and nontoxic.
API 570 INTERVAL / FREQUENCY & EXTENT OF INSPECTION
Extent of Visual External & CUI Inspections
External visual inspections, including inspections for CUI, should be conducted at maximum intervals listed in Table 2 to evaluate items such as those in API 574.
API 570 INTERVAL / FREQUENCY & EXTENT OF INSPECTION Extent of Thickness Measurement Inspection
To satisfy inspection interval requirements, each thickness measurement inspection should obtain thickness readings on a representative sampling of CMLs on each circuit.
INTERVAL / FREQUENCY & EXTENT OF INSPECTION Recommended Maximum Inspection Intervals
API 570
Type of Circuit
Thickness Measurements
Visual External
Class 1
Five years
Five years
Class 2
10 years
Five years
Class 3
10 years
lOyears
Class 4
Optional
Optional
Three years
By class
Injection points
a
—
S/A b
By class
NOTE Thickness measurements apply to systems for which CMLs have been established in accordance with 5.6. a Inspection intervals for potentially corrosive injection/mix points can also be established by a valid RBI analysis in accordance with API 580. b See API RP 574 for more information on S/A interfaces.
INTERVAL / FREQUENCY & EXTENT OF INSPECTION Recommended Maximum Inspection Intervals
Pipe Class
Approximate Amount of Follow-up Examination with NDE or Insulation Removal at Areas with Damaged Insulation
API 570
Approximate Amount of CUI Inspection by NDE at Suspect Areas on Piping Systems within Susceptible Temperature Ranges as indicated in API 574
1
75%
50%
2
50%
33%
3
25%
10%
4
Optional
Optional
API 570 INSPECTION DATA EVALUATION, ANALYSIS & RECORDING Corrosion Rate Determination
Remaining Life Calculation Long Term Corrosion Rate
Short Term Corrosion Rate
Long term and short term corrosion rates should be compared to see which results in the shortest remaining life as part of the data assessment.
API 570 INSPECTION DATA EVALUATION, ANALYSIS & RECORDING
MAWP Determination
The wall thickness used in these computations shall be the actual thickness as determined by inspection minus twice the estimated corrosion loss before the date of the next inspection
API 570 INSPECTION DATA EVALUATION, ANALYSIS & RECORDING
Required Thickness Determination
The required thickness of a pipe shall be the greater of the pressure design thickness or the structural minimum thickness.
Assessment of Inspection Findings
Pressure containing components found to have degradation that could affect their load carrying capability shall be evaluated for continued service. FitnessFor-Service techniques may be used for this evaluation.
API 570 INSPECTION DATA EVALUATION, ANALYSIS & RECORDING Types of Piping Records
Fabrication, Construction & Design Information Inspection History Repair, Alteration & Re-rating Information
Fitness-For-Service Assessment
API 510
PRESSURE VESSEL INSPECTION CODE:
API 510 PRESSURE VESSEL INSPECTION CODE: External Inspection Unless justified by an RBI assessment, each aboveground vessel shall be given a visual external inspection at an interval that does not exceed the lesser of five years or the required internal/on-stream inspection. External inspection for vessels in non-continuous service are the same as for vessels in continuous services.
API 510 PRESSURE VESSEL INSPECTION CODE: Internal and On-Stream Inspection
Unless justified by an RBI assessment, the period between internal or on-stream shall not exceed one half the remaining life of the vessel or 10 years, whichever is less. Whenever the remaining life is less than four years, the inspection interval may be the full remaining life up to a maximum of two years.
API 510 PRESSURE VESSEL INSPECTION CODE: Internal and On-Stream Inspection For pressure vessels that are in non-continuous service, the interval is based on the number of years of actual service provided that when idled, the vessel is: Isolated from the process fluids Not exposed to corrosive internal environments
API 653
TANK INSPECTION, REPAIR, ALTERATION & RECONSTRUCTION
API 653 INSPECTIONS FROM THE OUTSIDE OF THE TANK : Routine In-service Inspection The external condition of the tank shall be monitored by close visual inspection from the ground on a routine basis. This inspection may be done by owner/operator personnel. The interval of such inspections shall not exceed one month.
API 653 INSPECTIONS FROM THE OUTSIDE OF THE TANK : External Inspection All tanks shall be given a visual external inspection by an authorized inspector. This inspection shall be called the external inspection and must be conducted at least every five years or RCA/4N years (where RCA is the difference between the measured shell thickness and the minimum required thickness in mils, and N is the shell corrosion rate in mils per year) whichever is less.
API 653 INSPECTIONS FROM THE OUTSIDE OF THE TANK: Ultrasonic Thickness Inspection When used, the ultrasonic thickness measurements shall be made at intervals not to exceed the following: •When the corrosion rate is not known, the maximum interval shall be five years. •When the corrosion rate is know, the maximum interval shall be the smaller of RCA/2N years (where RCA is the difference between the measured shall thickness and the minimum required thickness in mils, and N is the shell corrosion rate in mils per year) or 15 years.
API 653 INSPECTIONS FROM THE OUTSIDE OF THE TANK : Internal Inspection Gather the data necessary for the minimum bottom and shell thickness assessments. Identify and evaluate any tank bottom settlement All tanks shall have a formal internal inspection conducted at the intervals defined by 6.4.2
API 653 INSPECTIONS FROM THE OUTSIDE OF THE TANK :
Inspection Intervals
The interval from initial service until the initial internal inspection shall not exceed 10 years.
