rp 581 inspection effectiveness

8/10/2019 Rp 581 Inspection Effectiveness

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DATE: 2-20-2012 API RP 581 Committee Meeting

API Ballot Proposal:

Removal of most of the language and all of the tables regarding inspection effectiveness from

the main body of Part 1 and Part 2 of API RP 581.

Reassembly of this information in a new annex of Part 2 that will discuss inspection

effectiveness and provide the tables per API RBI damage mechanism as examples for the user

to adapt and adopt to their specific knowledge and skills.

Technical Basis:

This will provide a good platform that emphasizes the user responsibility to understand and

apply RBI principles. In particular, it will consider:

a)

Philosophy behind the new tables and how to use them;

b)

Owner-User responsibility of adoption/adaptation;

c)

Methodology to account for confidence in inspection

d)

Application to PoF

Proposed By:

API RBI Software User Group: Inspection Effectiveness Review Sub-Committee


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API RP 581 RISK-BASED INSPECTION TECHNOLOGY

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PART 1

INSPECTION PLANNING USING API RBI TECHNOLOGY


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PART CONTENTS1

SCOPE

........................................................................................................................................... 42

REFERENCES

............................................................................................................................... 43

DEFINITIONS

................................................................................................................................. 44

API RBI CONCEPTS

..................................................................................................................... 44.1

Probability of Failure

............................................................................................................ 44.2

Consequence of Failure

....................................................................................................... 44.3

Risk Analysis

........................................................................................................................ 44.4

Inspection Planning Based on Risk Analysis

.................................................................... 44.4.1

Overview

........................................................................................................................ 44.4.2

Risk Target

.................................................................................................................... 44.4.3

Inspection Effecti veness The Value of Inspection

................................................. 44.4.4

Inspection Effecti veness Example

........................................................................... 54.4.5

Inspection Planning

...................................................................................................... 54.5

Nomenclature

........................................................................................................................ 64.6

Tables

..................................................................................................................................... 6

4.7

Figures

................................................................................................................................... 75

PRESSURE VESSELS AND PIPING

............................................................................................ 85.1


............................................................................................................ 85.2


....................................................................................................... 85.3

Risk Analysis

........................................................................................................................ 85.4


.................................................................... 86

ATMOSPHERIC STORAGE TANKS

............................................................................................. 96.1


............................................................................................................ 96.2


....................................................................................................... 96.3

Risk Analysis

........................................................................................................................ 96.4


.................................................................... 97

PRESSURE RELIEF DEVICES

................................................................................................... 107.1

General

................................................................................................................................. 107.2


.......................................................................................................... 107.2.1

Definition

..................................................................................................................... 107.2.2

Calculation of Probabilit y of Failure to Open

.......................................................... 107.2.3

PRD Demand Rate

...................................................................................................... 107.2.4

PRD Probabili ty of Failure on Demand

..................................................................... 10

7.2.5

Protected Equipment Failure Frequency as a Function of Overpressure

............ 117.2.6

Calculation Procedure

................................................................................................ 117.2.7

Overview

...................................................................................................................... 117.2.8

Calculation of Probability of Leakage

....................................................................... 117.2.9

Calculation Procedure

................................................................................................ 117.3

Consequence of PRD Failure to Open

.............................................................................. 117.4

Consequence of L eakage

.................................................................................................. 117.5

Risk Analysis

...................................................................................................................... 117.6


.................................................................. 117.7

Nomenclature

...................................................................................................................... 117.8

Tables

................................................................................................................................... 127.9

Figures

................................................................................................................................. 128

HEAT EXCHANGER TUBE BUNDLES

...................................................................................... 138.1

General

................................................................................................................................. 138.2

Methodology Overview

...................................................................................................... 138.3


.......................................................................................................... 138.4


..................................................................................................... 138.5

Risk Analysis

...................................................................................................................... 138.6


.................................................................. 138.6.1

Use of Risk Target in Inspection Planning

............................................................... 138.6.2

Example

....................................................................................................................... 13


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8.6.3

Inspection Planning Without Inspection History (First Inspection Date)

............. 138.6.4

Inspection Planning with Inspection History

........................................................... 138.6.5

Effects of Bundle Life Extension Efforts

.................................................................. 148.6.6

Future Inspection Recommendation

........................................................................ 148.7

Bundle Inspect/Replacement Decisions using Cost Benefit Analysis

......................... 148.8

Nomenclature

...................................................................................................................... 148.9

Tables

................................................................................................................................... 14


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1 SCOPE

2 REFERENCES

3 DEFINITIONS

4 API RBI CONCEPTS

4.1 Probability of Failure

4.2 Consequence of Failure

4.3 Risk Analysis

4.4 Inspection Planning Based on Risk Analysis

4.4.1 Overview

4.4.2 Risk Target

4.4.3 Inspection Effectiveness The Value of Inspection

An estimate of the probability of failure for a component is dependent on how well the independent variables ofthe limit state are known [10]. Using guidelines for inspection effectiveness given in API RBI, Part 2, Annex B.2aIn the models used for calculating the probability of failure, the flaw size (e.g. metal loss for thinning or cracksize for environmental cracking) may have significant uncertainty especially when these parameters need to beprojected into the future. An inspection program may be implemented in order to obtain a better estimate of thedamage rate and associated flaw size.

An inspection program is the combination of NDE methods (i.e. visual, ultrasonic, radiographic etc.), frequencyof inspection, and the location and coverage of an inspection in order to find a specific or set of damagemechanisms. Inspection programs vary in their effectiveness for locating and sizing damage, and thus fordetermining damage rates. Once the likely damage mechanisms have been identified, the inspection program

should must be evaluated in order to determine the effectiveness in f inding the identified mechanisms.

The effectiveness of an inspection program may be limited by:

a) Lack of coverage of an area subject to deterioration,

b) Inherent limitations of some inspection methods to detect and quantify certain types of deterioration,

c) Selection of inappropriate inspection methods and tools,

d) Application of methods and tools by inadequately trained inspection personnel,

e) Inadequate inspection procedures,

f) The damage rate under some conditions (e.g. start-up, shut-down, or process upsets) may increase thelikelihood or probability that failure may occur within a very short time; even if damage is not found during aninspection, failure may still occur as a result of a change or upset in conditions,

g) Inaccurate analysis of results leading to inaccurate trending of individual components, (problem with astatistical approach to trending), and

h) Probability of detection of the applied NDE technique for a given component type, metallurgy,temperature and geometry .

It is important to evaluate the benefits of multiple inspections and to also recognize that the most recent

inspection may best reflect the current state of the component under the current operating conditions. If theoperating conditions have changed, damage rates based on inspection data from the previous operatingconditions may not be valid. Determination of inspection effectiveness should consider the following:

a) Equipment or component type,

Formatted:para, No bullets or numbering

Formatted:para, No bullets or numbering


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a) Active and credible damage mechanism(s),b) Susceptibility to and rate of damage,

c) NDE methods, coverage and frequency, and

d) Accessibility to expected deterioration areas.

Inspection effectiveness may be introduced into the probability of failure calculation by using Bayesian analysisor more directly by modifying the model for the independent variables, the distribution function, and/or thedistribution function parameters. For example, if the model for metal loss is determined to be a lognormaldistribution, the distribution parameters, mean and coefficient of variation, may be changed based on the NDEmethod and coverage used during an inspection. Extending this concept further, a series of standard inspectioncategories may be defined, and the distribution parameters adjusted based on the NDE method and coveragedefined for each standard category.

In API RBI, examples of the inspection effectiveness categories for various damage mechanisms and theassociated inspections recommended (i.e. NDE technique and coverage) for each damage mechanism areprovided inPart 2,Annex 2.C. These are provided as examples to the user and represent minimally acceptableinspections per damage mechanism, corresponding to various inspection effectiveness ratings. The usershould adopt and modify similar tables according to specific risk management plans and experience-basedinspection programs. In addition, the rules for combining the benefits of multiple inspections are also providedin Part 2

By identifying credible damage mechanisms, determining the damage rate, and selecting an inspectioneffectiveness category based on a defined level of inspection, a probability of failure and associated risk may bedetermined using

.

Equations (1.8) or (1.9)

4.4.4 Inspection Effecti veness Example

. The probability of failure and risk may be determined using theseequations for future time periods or conditions as well as current conditions by projecting the damage rate andassociated flaw size into the futurean inspection program will become more effective.

In API RBI, the inspection effectiveness is graded A through E, with an A inspection providing the most effectiveinspection available (90% effective) and E representing no inspection. A description of the inspection effectivelevels for general thinning damage is provided in Part 2

To illustrate the method in which different inspection levels effect the damage factor and probability of failure,consider the example of the general thinning damage mechanism (procedures for modifying damage factorsbased on inspection effectiveness are provided in API 581 for all damage mechanisms). For general thinning,

API RBI utilizes an approach based on a metal loss parameter,

, Table 5.5.

rtA . The damage factor is calculated as a

function of this parameter and is based on the premise that as a pressure vessel or piping wall corrodes below

the construction Code minimum wall thickness plus the specified corrosion allowance, the damage factor wi llincrease. An inspection program for general thinning will result in a reduction of the damage factor based on theeffectiveness of the inspection to quantify the corrosion rate. As an example, the general thinning damage

factor,thin

fD , for a component with an rtA equal to 0.5 is 1200 if there is no inspection (i.e. Inspection

Effectiveness is E) as shown in Part 2, Table 5.5. If a B level inspection is performed, the damage factor isreduced to 600. If two B level inspections have been completed, the damage factor is further reduced to 200.

When these damage factors are substituted into Equation (1.1),

4.4.54.4.4 Inspection Planning

it becomes apparent that an effective inspectionprogram can reduce the probability of failure of a component and the risk of loss of containment.

In planning inspections using API RBI, a plan date is typically chosen far enough out into the future to include atime period covering one or several future maintenance turnarounds. Within this period, three cases arepossible based on predicted risk and the specified risk target.

a) Case 1 Risk target is exceeded at a point in the future prior to the inspection plan date This is theclassical case and is represented inFigure 4.3. In this case, the results of an inspection plan will be thenumber of inspections required, as well as the type or inspection effectiveness required, to reduce the riskat the future plan date down below the risk target. The target date is the date where the risk target is

expected to be reached and is the date of the recommended inspection.
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b) Case 2 Risk already exceeds the risk target at the time the RBI analysis is performed This case isshown in Figure 4.4and indicates that the current risk at the time of the RBI analysis exceeds the risktarget. An immediate inspection will be recommended at a level sufficient to reduce the risk at the futureplan date down below the risk target.

c) Case 3 Risk at the future plan date does not exceed the risk target This case is shown in Figure 4.5and indicates that the predicted future risk at the plan date will not exceed the risk target and therefore, noinspection is recommended during the plan period. In this case, the inspection due date for inspectionscheduling purposes should be adjusted to the plan date indicating that an evaluation of the equipment forInspection or re-analysis of risk should be performed by the plan end date.

The concept of how the different inspection techniques with different effectiveness levels can reduce risk isshown inFigure 4.3. In the example shown, a B Level inspection was recommended at the target date. This

inspection level was sufficient since the risk predicted after the inspection was performed was determined to bebelow the risk target at the plan date. Note that inFigure 4.3,a D Levelinspection at the target date would not

have been sufficient to satisfy the risk target criteria. The projected risk at the plan date would have exceededthe risk target.

4.5 Nomenclature

4.6 Tables


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4.7 Figures

Figure 4.3 Case 1: Inspection Planning When th e Risk Target is Exceeded Between th e RBI Date andthe Plan Date and the Impact of Inspection at Various Levels of Effectiveness

time

Risk

Installation

Date

RBI

Date

Target Date,

InspectionPerformed

Plan

Date

Risk Target

Total Risk with

Inspection at the

Risk Target Date

Total Risk without

Inspection at the

Risk Target Date

A

B

C

D


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5 PRESSURE VESSELS AND PIPING



5.3 Risk Analysis


The procedure to determine an inspection plan is provided inparagraph 4.4and is supplemented by Annex 2.C.This procedure may be used to determine both the time and type of inspection to be performed based on theprocess fluid and design conditions, component type and materials of construction, and the active damagemechanisms.


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6 ATMOSPHERIC STORAGE TANKS



6.3 Risk Analysis


The procedure to determine an inspection plan is provided inparagraph 4.4and is supplemented by Annex 2.C.This procedure may be used to determine both the time and type of inspection to be performed based on theprocess fluid and design conditions, component type and materials of construction, and the active damagemechanisms.


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7 PRESSURE RELIEF DEVICES

7.1 General


7.2.1 Definition

7.2.2 Calculation of Probabilit y of Failure to Open

7.2.3 PRD Demand Rate

7.2.4 PRD Probability of Failure on Demand

a) General

b) Categories of Service Severity

c) Default Probability of Failure on Demand vs Time in Service

d) Default Data for Balanced Bellows Pressure Relief Valves

e) Default Weibull Parameters for Pilot-Operated Pressure Relief Valves

f) Default Weibull Parameters for Rupture Disks

g) Adjustment for Conventional PRVs Discharging to Closed System

h) Adjustment for Overpressures Higher than Set Pressure

i) Adjustment for Environmental Factors

j) Presence of an Upstream Rupture Disk

k) Use of Plant Specific Failure Data

l) Modification of Failure on Demand Based on PRD Specific Testing Data

1) Tracking Historical Inspection and Testing Data

2) Determine the Effectiveness of Inspection Programs in Confirming Failure Rates

Inspection programs vary in their effectiveness for determining failure rates. The definitions forinspection effectiveness used by API RBI are provided in Table 7.7

Aan inspection and testing program should track the effectiveness of the inspection and the testingperformed for each pressure relief device. The concept of inspection effectiveness is similar to theconcept that is described in

. The inspections effectiveness isbased on the inspections ability to adequately predict the failure (or pass) state of the PRD being

inspected. Limitations in the ability of a program to improve confidence in the failure rate result from theinability of some test methods to detect and quantify damage.For pressure relief devices,

paragraph 4.4.3

Default confidence values, based on expert opinion, are provided in

Annex 2.C of this documentfor fixed equipment. With Forinspection effectiveness for pressure relief devices, a measure of confidence in the Pass/Fail/Leakresult of the inspection effort is obtainedutilized. For a full discussion of inspection effectiveness asrelated to pressure relief devices, refer to Annex 2.C.

Table 7.8, indicating the level ofconfidence each of the three levels of inspection effectiveness will accurately represent actual PRDperformance in an overpressure demand case. For example, the 90% effectiveness associated withpassing a highly effective bench test means that there is a 90% probability the valve would haveopened upon demand in its installed service. Therefore, it also carries a 10% probability that the PRDwould have failed upon demand during operation. The values shown in Table 7.8

The conditional probabilities listed reflect the confidence that an inspection result will predict thedevices performance upon demand. For passing PRDs, the highest confidence is assigned when the

PRD is bench tested without any prior cleaning (i.e. as-received condition.) Bench testing where thedevices are cleaned prior to testing, in-situ testing, and visual inspections provide some informationabout PRD performance, but are not considered as reliable as the as-received bench test.

are called conditional

probabilities.


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The philosophy is different for PRDs that fail an inspection. In the case of a highly effective bench testfailure, the 95% confidence translates to a 95% chance that the PRD would have failed upon demand inactual service. Unlike the passing test case, the usually effective in-situ test, or bench test where thevalve has been steamed out prior to testing, is assumed to have the same 95% confidence for failureupon demand in actual service.

An ineffective test does not provide any information to predict PRD performance upon demand andtherefore the PRD does not receive any credit for the test/inspection date. The inspection still will getsome credit if an overhaul was performed in that the valve is assumed to be returned to service in like-new condition, and the in-service duration is calculated from the ineffective inspection date.

3) Inspection Updating

4) Example Bayesian Updating Calculation

5) Updating Failure Rates after Modification to the Design of the PRD

7.2.5 Protected Equipment Failure Frequency as a Function of Overpressure

7.2.6 Calculation Procedure

7.2.7 Overview7.2.8 Calculation of Probability of Leakage

7.2.9 Calculation Procedure

7.3 Consequence of PRD Failure to Open

7.4 Consequ ence of Leakage

7.5 Risk Analysis


7.7 Nomenclature


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PART CONTENTS1

SCOPE

........................................................................................................................................... 82

REFERENCES

............................................................................................................................... 83

DEFINTIONS

.................................................................................................................................. 84

PROBABILITY OF FAILURE CALCULATIONS

........................................................................... 84.1

Overview

................................................................................................................................ 84.2

Calculation of Probability of Failure

................................................................................... 84.3

Generic Failure Frequency

.................................................................................................. 84.4

Damage Factor

...................................................................................................................... 84.4.1

Overview

........................................................................................................................ 84.4.2

Damage Factor Combinatio n for Multipl e Damage Mechanisms

............................ 84.4.3

Inspection Effectiveness Category

............................................................................. 84.5

Management Systems Factor

.............................................................................................. 84.5.1

General

........................................................................................................................... 84.5.2

Overview

........................................................................................................................ 84.5.3

Aud it ing Tech nique

...................................................................................................... 84.5.4

Calculation of the Management Systems Factor

....................................................... 84.6

Nomenclature

........................................................................................................................ 84.7

Tables

..................................................................................................................................... 95

THINNING DAMAGE FACTOR

................................................................................................... 105.1

Scope

................................................................................................................................... 105.2

Screening Criteria

............................................................................................................... 105.3

Required Data

..................................................................................................................... 105.4

Basic Assumptions

............................................................................................................ 105.5

Determination of t he Damage Factor

................................................................................ 105.5.1

Overview

...................................................................................................................... 105.5.2

Inspection Effectiveness

............................................................................................ 105.5.3

Calculation of the Damage Factor

............................................................................. 105.6

Nomenclature

...................................................................................................................... 105.7

Tables

................................................................................................................................... 106

COMPONENT LINING DAMAGE FACTOR

................................................................................ 157

SCC DAMAGE FACTOR CAUSTIC CRACKING

.................................................................... 167.1

Scope

................................................................................................................................... 167.2

Description of Damage

....................................................................................................... 167.3

Screening Criteria

............................................................................................................... 16

7.4

Required Data

..................................................................................................................... 167.5

Basic Assumptions

............................................................................................................ 167.6


................................................................................ 167.6.1

Overview

...................................................................................................................... 167.6.2


............................................................................................ 167.6.3


............................................................................. 167.7

Nomenclature

...................................................................................................................... 167.8

References

.......................................................................................................................... 167.9

Tables

................................................................................................................................... 168

SCC DAMAGE FACTOR AMINE CRACKING

......................................................................... 188.1

Scope

................................................................................................................................... 188.2


....................................................................................................... 188.3

Screening Criteria

............................................................................................................... 188.4

Required Data

..................................................................................................................... 188.5

Basic Assumptions

............................................................................................................ 188.6


................................................................................ 188.6.1

Overview

...................................................................................................................... 188.6.2


............................................................................................ 18

8.6.3


............................................................................. 18


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8.7

Nomenclature

...................................................................................................................... 188.8

References

.......................................................................................................................... 188.9

Tables

................................................................................................................................... 189

SCC DAMAGE FACTOR SULFIDE STRESS CRACKING

..................................................... 209.1

Scope

................................................................................................................................... 209.2


....................................................................................................... 209.3

Screening Criteria

............................................................................................................... 209.4

Required Data

..................................................................................................................... 209.5

Basic Assumptions

............................................................................................................ 209.6


................................................................................ 209.6.1

Overview

...................................................................................................................... 209.6.2


............................................................................................ 209.6.3


............................................................................. 209.7

Nomenclature

...................................................................................................................... 209.8

References

.......................................................................................................................... 209.9

Tables

................................................................................................................................... 2010

SCC DAMAGE FACTOR HIC/SOHIC-H2 S .............................................................................. 2210.1

Scope

................................................................................................................................... 22

10.2


....................................................................................................... 2210.3

Screening Criteria

............................................................................................................... 2210.4

Required Data

..................................................................................................................... 2210.5

Basic Assumptions

............................................................................................................ 2210.6


................................................................................ 2210.6.1

Overview

...................................................................................................................... 2210.6.2


............................................................................................ 2210.6.3


............................................................................. 2210.7

Nomenclature

...................................................................................................................... 2210.8

References

.......................................................................................................................... 2210.9

Tables

................................................................................................................................... 2211

SCC DAMAGE FACTOR CARBONATE CRACKING

............................................................. 2411.1

Scope

................................................................................................................................... 2411.2


....................................................................................................... 2411.3

Screening Criteria

............................................................................................................... 2411.4

Required Data

..................................................................................................................... 2411.5

Basic Assumptions

............................................................................................................ 2411.6


................................................................................ 2411.6.1

Overview

...................................................................................................................... 2411.6.2


............................................................................................ 2411.6.3


............................................................................. 2411.7

Nomenclature

...................................................................................................................... 2411.8

References

.......................................................................................................................... 2411.9

Tables

................................................................................................................................... 2412

SCC DAMAGE FACTOR PTA CRACKING

............................................................................. 2612.1

Scope

................................................................................................................................... 2612.2


....................................................................................................... 2612.3

Screening Criteria

............................................................................................................... 2612.4

Required Data

..................................................................................................................... 2612.5

Basic Assumptions

............................................................................................................ 2612.6


................................................................................ 2612.6.1

Overview

...................................................................................................................... 2612.6.2


............................................................................................ 2612.6.3


............................................................................. 2612.7

Nomenclature

...................................................................................................................... 26

12.8

References

.......................................................................................................................... 2612.9

Tables

................................................................................................................................... 2613

SCC DAMAGE FACTOR CLSCC

............................................................................................ 28


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13.1

Scope

................................................................................................................................... 2813.2


....................................................................................................... 2813.3

Screening Criteria

............................................................................................................... 2813.4

Required Data

..................................................................................................................... 2813.5

Basic Assumptions

............................................................................................................ 2813.6


................................................................................ 2813.6.1

Overview

...................................................................................................................... 2813.6.2


............................................................................................ 2813.6.3


............................................................................. 2813.7

Nomenclature

...................................................................................................................... 2813.8

References

.......................................................................................................................... 2813.9

Tables

................................................................................................................................... 2814

SCC DAMAGE FACTOR HSC-HF

........................................................................................... 3014.1

Scope

................................................................................................................................... 3014.2


....................................................................................................... 3014.3

Screening Criteria

............................................................................................................... 3014.4

Required Data

..................................................................................................................... 3014.5

Basic Assumptions

............................................................................................................ 30

14.6


................................................................................ 3014.6.1

Overview

...................................................................................................................... 3014.6.2


............................................................................................ 3014.6.3


............................................................................. 3014.7

Nomenclature

...................................................................................................................... 3014.8

References

.......................................................................................................................... 3014.9

Tables

................................................................................................................................... 3015

SCC DAMAGE FACTOR HIC/SOHIC-HF

................................................................................ 3215.1

Scope

................................................................................................................................... 3215.2


....................................................................................................... 3215.3

Screening Criteria

............................................................................................................... 3215.4

Required Data

..................................................................................................................... 3215.5

Basic Assumptions

............................................................................................................ 3215.6


................................................................................ 3215.6.1

Overview

...................................................................................................................... 3215.6.2


............................................................................................ 3215.6.3


............................................................................. 3215.7

Nomenclature

...................................................................................................................... 3215.8

References

.......................................................................................................................... 3215.9

Tables

................................................................................................................................... 3216

EXTERNAL CORROSION DAMAGE FACTOR FERRITIC COMPONENT

............................ 3416.1

Scope

................................................................................................................................... 3416.2


....................................................................................................... 3416.3

Screening Criteria

............................................................................................................... 3416.4

Required Data

..................................................................................................................... 3416.5

Basic Assumption

.............................................................................................................. 3416.6


................................................................................ 3416.6.1

Overview

...................................................................................................................... 3416.6.2


............................................................................................ 3416.6.3


............................................................................. 3416.7

Nomenclature

...................................................................................................................... 3416.8

Tables

................................................................................................................................... 3417

CUI DAMAGE FACTOR FERRITIC COMPONENT

................................................................. 36


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17.1

Scope

................................................................................................................................... 3617.2


....................................................................................................... 3617.3

Screening Criteria

............................................................................................................... 3617.4

Required Data

..................................................................................................................... 3617.5

Basic Assumption

.............................................................................................................. 3617.6


................................................................................ 3617.6.1

Overview

...................................................................................................................... 3617.6.2


............................................................................................ 3617.6.3


............................................................................. 3617.7

Nomenclature

...................................................................................................................... 3617.8

Tables

................................................................................................................................... 3618

EXTERNAL CLSCC DAMAGE FACTOR AUSTENITIC COMPONENT

................................. 3918.1

Scope

................................................................................................................................... 3918.2


....................................................................................................... 3918.3

Required Data

..................................................................................................................... 3918.4

Basic Assumption

.............................................................................................................. 3918.5


................................................................................ 3918.5.1

Overview

...................................................................................................................... 39

18.5.2


............................................................................................ 3918.5.3


............................................................................. 3918.6

Nomenclature

...................................................................................................................... 3918.7

Tables

................................................................................................................................... 3919

EXTERNAL CUI CLSCC DAMAGE FACTOR AUSTENITIC COMPONENT

.......................... 4119.1

Scope

................................................................................................................................... 4119.2


....................................................................................................... 4119.3

Screening Criteria

............................................................................................................... 4119.4

Required Data

..................................................................................................................... 4119.5

Basic Assumption

.............................................................................................................. 4119.6


................................................................................ 4119.6.1

Overview

...................................................................................................................... 4119.6.2


............................................................................................ 4119.6.3


............................................................................. 4119.7

Nomenclature

...................................................................................................................... 4119.8

Tables

................................................................................................................................... 4120

HTHA DAMAGE FACTOR

........................................................................................................... 4320.1

Scope

................................................................................................................................... 4320.2


....................................................................................................... 4320.3

Screening Criteria

............................................................................................................... 4320.4

Required Data

..................................................................................................................... 4320.5

Basic Assumption

.............................................................................................................. 4320.6


................................................................................ 4320.6.1

Overview

...................................................................................................................... 4320.6.2


............................................................................................ 4320.6.3


............................................................................. 4320.7

Nomenclature

...................................................................................................................... 4320.8

Tables

................................................................................................................................... 4321

BRITTLE FACTURE DAMAGE FACTOR

................................................................................... 4521.1

Scope

................................................................................................................................... 4521.2


....................................................................................................... 4521.3

Screening Criteria

............................................................................................................... 4521.4

Required Data

..................................................................................................................... 4521.5

Basic Assumption

.............................................................................................................. 4521.6


................................................................................ 45

21.6.1

Overview

...................................................................................................................... 4521.6.2


............................................................................................ 4521.6.3


............................................................................. 45


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21.7

Nomenclature

...................................................................................................................... 4521.8

Tables

................................................................................................................................... 4522

TEMPER EMBRITTLEMENT DAMAGE FACTOR

...................................................................... 4622.1

Scope

................................................................................................................................... 4622.2


....................................................................................................... 4622.3

Screening Criteria

............................................................................................................... 4622.4

Required Data

..................................................................................................................... 4622.5

Basic Assumption

.............................................................................................................. 4622.6


................................................................................ 4622.6.1

Overview

...................................................................................................................... 4622.6.2


............................................................................................ 4622.6.3


............................................................................. 4622.7

Nomenclature

...................................................................................................................... 4622.8

References

.......................................................................................................................... 4622.9

Tables

................................................................................................................................... 4623

885 EMBRITTLEMENT DAMAGE FACTOR

............................................................................... 4723.1

Scope

................................................................................................................................... 4723.2


....................................................................................................... 47

23.3

Screening Criteria

............................................................................................................... 4723.4

Required Data

..................................................................................................................... 4723.5

Basic Assumption

.............................................................................................................. 4723.6


................................................................................ 4723.6.1

Overview

...................................................................................................................... 4723.6.2


............................................................................................ 4723.6.3


............................................................................. 4723.7

Nomenclature

...................................................................................................................... 4723.8

References

.......................................................................................................................... 4723.9

Tables

................................................................................................................................... 4724

SIGMA PHASE EMBRITTLEMENT DAMAGE FACTOR

........................................................... 4824.1

Scope

................................................................................................................................... 4824.2


....................................................................................................... 4824.3

Screening Criteria

............................................................................................................... 4824.4

Required Data

..................................................................................................................... 4824.5

Basic Assumption

.............................................................................................................. 4824.6


................................................................................ 4824.6.1

Overview

...................................................................................................................... 4824.6.2


............................................................................................ 4824.6.3


............................................................................. 4824.7

Nomenclature

...................................................................................................................... 4824.8

References

.......................................................................................................................... 4824.9

Tables

................................................................................................................................... 4825

PIPING MECHANICAL FATIGUE DAMAGE FACTOR

.............................................................. 4925.1

Scope

................................................................................................................................... 4925.2


....................................................................................................... 4925.3

Screening Criteria

............................................................................................................... 4925.4

Required Data

..................................................................................................................... 4925.5

Basic Assumption

.............................................................................................................. 4925.6


................................................................................ 4925.6.1

Overview

...................................................................................................................... 4925.6.2


............................................................................................ 4925.6.3


............................................................................. 5025.7

Nomenclature

...................................................................................................................... 5025.8

Tables

................................................................................................................................... 50


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2-8

1 SCOPE

2 REFERENCES

3 DEFINTIONS

4 PROBABILITY OF FAILURE CALCULATIONS

4.1 Overview

4.2 Calculation of Probability of Failure

4.3 Generic Failure Frequency

4.4 Damage Factor

4.4.1 Overview

4.4.2 Damage Factor Combination for Multip le Damage Mechanisms

4.4.3 Inspection Effectiveness Category

Damage factors are determined as a function of inspection effectiveness. Inspection effectiveness discussionand example tables are provided in Annex 2.C of this document. The five inspection effectiveness categoriesused in API RBI are shown in Table 4.3

Inspections are ranked according to their expected effectiveness at detecting damage and correctly predictingthe rate of damage. The actual effectiveness of a given inspection technique depends on the characteristics ofthe damage mechanism.

. The inspection effectiveness categories presented are meant to beexamples and in order to provide a guideline for the user inforassigning actual inspection effectiveness. Theactual effectiveness of any inspection technique depends on many factors such as the skill and training ofinspectors, and the level of expertise used in selecting inspection locations.

The effectiveness of each inspection performed within the designated time period is characterized for eachdamage mechanism. The number of highest effectiveness inspections will be used to determine the damagefactor. If multiple inspections of a lower effectiveness have been cond ucted during the designated time period,they can be approximated to an equivalent higher effectiveness inspection in accordance with the followingrelationships:

a) 2 Usually Effective (B) Inspections = 1 Highly Effective (A) Inspection, or 2B = 1A

b) 2 Fairly Effective (C) Inspections = 1 Usually Effective (B) inspection, or 2C = 1B

c) 2 Poorly Effective (D) Inspections = 1 Fairly Effective (C) inspection, or 2D = 1C

Note that these equivalent higher inspection rules shall not be applied to No Inspections (E).

4.5 Management Systems Factor

4.5.1 General

4.5.2 Overview

4.5.3 Auditin g Technique

4.5.4 Calculation of the Management Systems Factor

4.6 Nomenclature


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2-9

4.7 Tables

Table 4.3 Inspection Effecti veness Categories

Qualitative InspectionEffectiveness

CategoryDescription

Highly EffectiveThe inspection methods will correctly identify the true damage state in nearlyevery case (or 80100% confidence).

Usually EffectiveThe inspection methods will correctly identify the true damage state most ofthe time (or 6080% confidence).

Fairly EffectiveThe inspection methods will correctly identify the true damage state about halfof the time (or 4060% confidence).

Poorly Effective The inspection methods will provide little information to correctly identify thetrue damage state (or 2040% confidence).

IneffectiveThe inspection method will provide no or almost no information that willcorrectly identify the true damage state and are considered ineffective fordetecting the specific damage mechanism (less than 20% confidence).


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2-10

5 THINNING DAMAGE FACTOR

5.1 Scope

5.2 Screening Criteria

5.3 Required Data

5.4 Basic Assumpti ons

5.5 Determinatio n of the Damage Factor

5.5.1 Overview

5.5.2 Inspection Effectiveness

Inspections are ranked according to their expected effectiveness at detecting thinning and correctly predictingthe rate of thinning. The actual effectiveness of a given inspection technique depends on the characteristics ofthe thinning mechanism, (i.e., whether it is general or localized).

Examples of inspection activities for general and localized thinning, respectively, that are both intrusive (requiresentry into the equipment), non-intrusive (can be performed externally), and buried components are provided inAnnex 2.C,Tables 5.57.1,7.2, and 7.3through 5.7, respectively. Examples of inspection activities for generaland localized thinning, regarding tank shell courses and bottoms are provided in Annex 2.C,Tables 7.4 to 7.6.Note that the effectiveness category assigned to the inspection activity differs depending on whether thethinning is general or localized.

For localized thinning, selection of locations for examination must be based on a thorough understanding of thedamage mechanism in the specific process.

The effectiveness of each inspection performed within the designated time period must be characterized inaccordance a manner similar to with the examples provided in Annex 2.C,Tables 5.57.1 through 5.107.6,asapplicable. The number and category of the highest effective inspection will be used to determine the damagefactor. If multiple inspections of a lower effectiveness have been conducted during the designated time period,they can be equated to an equivalent higher effectiveness inspection in accordance with paragraph 4.4.3

5.5.3 Calculation of the Damage Factor

. Notethat for tank bottoms, credit is given for only one inspection.

5.6 Nomenclature

5.7 Tables

Table 5.5 Guidelines for Assi gning Inspectio n Effectiveness General Thinning

InspectionCategory

InspectionEffectiveness

CategoryIntrusive Inspection Example Non-intrusive Inspection Example

AHighly

Effective

50 to 100% examination of thesurface (partial internalsremoved), and accompanied bythickness measurements

50 to 100% ultrasonic scanningcoverage (automated or manual) orprofile radiography

BUsuallyEffective

Nominally 20% examination (nointernals removed), and spotexternal ultrasonic thicknessmeasurements

Nominally 20% ultrasonic scanningcoverage (automated or manual), orprofile radiography, or external spotthickness (statistically validated)


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Table 5.7 Guidelines for Assi gning Inspecti on Effectiveness Buried Components

InspectionCategory

InspectionEffectiveness Category

Intrusive InspectionExample

Non-intrusiveInspection Example

Non-intrusiveInspection Example

A Highly Effective

100% internal inspectionvia state-of-the-art piggingand in-line inspectiontechnologies (UT, MFL,internal rotary UT, etc.)

100% external inspectionof equipment that is onlypartially buried using anNDE crawler withcircumferential inspectiontechnology (MFL, lamb-wave UT)

Complete excavation,100% external visualinspection, and 100%inspection with NDEtechnologies (UTthickness measurementsuch as handheld devicesat close-interval gridlocations, UT B-scan,automated ultrasonicscanning, guided-waveUT global search, crawlerwith circumferentialinspection technology

such as MFL or lamb-wave UT, digitalradiography in more thanone direction)

a. Cathodic Protection(CP) Systemmaintained andmanaged by NACEcertified personnel andcomplying with NACESP0169 [14

b. Close Interval Survey(at excavation sites) toassess theperformance of the CPsystem locally

] includesStray current surveyson a regular basis

c.a. Sample soil andwater resistivity andchemistrymeasurements alongentire structure

BUsuallyEffective

Internal inspection viapigging and in-lineinspection technologies(UT, MFL, internal rotaryUT, etc.) of selected areas/ sections, combined withstatistical analysis orextreme value analysis(EVA).

External inspection ofequipment that is onlypartially buried using anNDE crawler withcircumferential inspection

technology (MFL, lamb-wave UT) on selectedareas / sections,combined with statisticalanalysis or extreme valueanalysis (EVA).

Excavation at Selectedlocations, 100% externalvisual, and 100%inspection with NDEtechnologies (UTthickness measurementsuch as handheld devicesat close-interval gridlocations, UT B-scan,automated ultrasonicscanning, guided-waveUT global search, crawlerwith circumferentialinspection technologysuch as MFL or lamb-

wave UT, digitalradiography in more thanone direction)

a. CP System maintainedand managed byNACE certifiedpersonnel andcomplying with NACESP0169 [14

b. Close Interval Survey(at excavation sites) toassess theperformance of the CPsystem locally

] includesStray current surveyson a regular basis

c. Sample soil and waterresistivity and

chemistrymeasurements alongentire structure

d.a. DC VoltageGradient (DCVG) todetermine coatingdamage

C Fairly Effective

Partly inspection byinternal smart pig orspecialized crawlerdevice, including arepresentative portion ofthe buried pipe. (


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2-13

Table 5.8 Guidelines f or Ass igning Inspection Eff ectiveness Tank Shell Course InternalCorrosion

InspectionCategory


Category

Inspection

A Highly Effective

a. Intrusive inspection good visual inspection with pit depth gage measurementsat suspect locations.

b.a. UT scanning follow up on suspect location and as general confirmation of wallthickness

BUsuallyEffective

a. External spot UT scanning based on visual information from previous internalinspection of this tank or similar service tanks.

b.a. Internal video survey with external UT follow-up.

C Fairly EffectiveEternal spot UT scanning based at suspect locations without benefit of any internalinspection information on tank type or service.

D Poorly Effective

External spot UT based at suspect locations without benefit of any internal inspection

information on tank type or service.

E Ineffective No inspection

Table 5.9 Guid elines for A ssi gni ng Insp ecti on Effect iveness Tank Sh ell Course ExternalCorrosion

InspectionCategory


Category

Inspection

A Highly Effective

a. Insulated >95% external visual inspection prior to removal of insulation

b. Remove >90% of insulation at suspect locations, OR >90% pulse eddy currentinspection.

c. Visual inspection of the exposed surface area with follow-up by UT or pitgauge as required.

a. Non-Insulated - >95% v isual inspection of the exposed surface area withfollow-up by UT or pit gauge as required.

B Usually Effective

a. Insulated >95% external visual inspection prior to removal of insulationb. Remove >30% of insulation at suspect locations, OR >30% pulse eddy current

inspection.



C Fairly Effective





D Poorly Effective






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2-15

6 COMPONENT LINING DAMAGE FACTOR

6.1 Scope


6.3 Required Data



6.5.1 Overview


Inspections are ranked according to their expected effectiveness at detecting the specific damage mechanism.Examples of inspection activities that are both intrusive (requires entry into the equipment) and non-intrusive(can be performed externally), are provided inAnnex 2.C, Table 7.7.

6.5.26.5.3 Calculation of the Damage Factor

6.6 Nomenclature

6.7 Tables

6.8 Figures


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2-16

7 SCC DAMAGE FACTOR CAUSTIC CRACKING

7.1 Scope

7.2 Description of Damage


7.4 Required Data



7.6.1 Overview


Inspections are ranked according to their expected effectiveness at detecting caustic crackingthe specificdamage mechanism and correctly predicting the rate of damage.

Examples of inspection activities for caustic cracking that are both intrusive (requires entry into the equipment)and non-intrusive (can be performed externally), are provided in Table 7.2Annex

The effectiveness of each inspection performed within the designated time period must be characterized inaccordance with

2.C, Table 7.8.

Table 7.2. The number and category of the highest effective inspection will be used todetermine the damage factor. If multiple inspections of a lower effectiveness have been conducted during thedesignated time period, they can be equated to an equivalent higher effectiveness inspection in accordance withparagraph 4.4.3


.

7.7 Nomenclature

7.8 References

7.9 Tables

Table 7.2 Guidelines fo r Assig ning Inspecti on Effectiveness Caustic Cracking

InspectionCategory



AHighly

Effective

Wet fluorescent Magneticparticle or dye penetrant testingof 25-100% of welds/cold bends;or Dye penetrant testing of 25-100% of welds/cold bends.

Shear wave ultrasonic testing of 25-100% of welds/cold bends; orRadiographic testing of 50-100% ofwelds/cold bends.

B

Usually

Effective

Wet fluorescent Magneticparticle or dye penetrant testing

of 10-24% of welds/cold bends;or Dye penetrant testing of 10-24% of welds/cold bends.

Shear wave ultrasonic testing of 10-24% of welds/cold bends; or

Radiographic testing of 25-49% ofwelds/cold bends.


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2-17

C Fairly Effective

Magnetic particle or dyepenetrant testing of less than10% of welds/cold bends; or Dyepenetrant testing of less than10% of welds/cold bends.

Shear wave ultrasonic testing of lessthan 10% of welds/cold bends; orRadiographic testing of less than 25%of welds/cold bends.

DPoorly

EffectiveVisual inspection Visual inspection for leaks

E Ineffective No inspection No inspection


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2-18

8 SCC DAMAGE FACTOR AMINE CRACKING

8.1 Scope



8.4 Required Data



8.6.1 Overview




Inspections are ranked according to their expected effectiveness at detecting amine cracking and correctlypredicting the rate of damage.

Examples of inspection activities for Amine cracking that are both intrusive (requires entry into the equipment)and non-intrusive (can be performed externally), are provided in Table 8.2


.

Table 8.2. The number and category of the highest effective inspection will be used todetermine the damage factor. If multiple inspections of a lower effectiveness have been conducted during thedesignated time period, they can be equated to an equivalent higher effectiveness inspection in accordance withparagraph 4.4.3.


8.7 Nomenclature

8.8 References

8.9 Tables

Table 8.2 Guidelines fo r Assig ning Inspectio n Effectiveness Ami ne Cracki ng

InspectionCategory



AHighly

Effective

Wet fluorescent magnetic particletesting of 100% of repair weldsand 50-100% of other welds/cold

bends.

None

BUsuallyEffective

Wet fluorescent magnetic particletesting of 20-49% of welds/cold

Shear wave ultrasonic testing of 50-100% of welds/cold bends; or Acoustic


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2-19

bends. Emission testing with follow-up shearwave UT.

C Fairly Effective

Wet fluorescent magnetic particletesting of less than 20% ofwelds/cold bends; or Drymagnetic particle testing of 50-100% of welds/cold bends; or Dyepenetrant testing of 50-100% ofwelds/cold bends.

Shear wave ultrasonic testing of 20-49%of welds/cold bends.

DPoorly

Effective

Dry magnetic particle testing ofless than 50% of welds/coldbends; or Dye penetrant testing ofless than 50% of welds/coldbends.

Shear wave ultrasonic testing of lessthan 20% of welds/cold bends; orRadiographic testing; or Visualinspection for leaks.

E Ineffective Visual inspection No inspection


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2-20

9 SCC DAMAGE FACTOR SULFIDE STRESS CRACKING

9.1 Scope



9.4 Required Data



9.6.1 Overview




Inspections are ranked according to their expected effectiveness at detecting sulfide stress cracking andcorrectly predicting the rate of damage.

Examples of inspection activities for sulfide stress cracking that are both intrusive (requires entry into theequipment) and non-intrusive (can be performed externally), are provided in Table 9.2


.

Table 9.2 The number and category of the highest effective inspection will be used todetermine the damage factor. If multiple inspections of a lower effectiveness have been conducted during thedesignated time period, they can be equated to an equivalent higher effectiveness inspection in accordance withparagraph 4.4.3


.

9.7 Nomenclature

9.8 References

9.9 Tables

Table 9.2 Guidelines fo r Assig ning Inspecti on Effectiveness Sulfide Stress Cracking

InspectionCategory



AHighly

Effective

Wet fluorescent magneticparticle testing of 25-100% of

weldments.

Shear wave ultrasonic testing of 25-100% of weldments, transverse and

parallel to the weld with the weld capremoved; or Acoustic Emission testingwith follow-up shear wave UT.


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2-21

BUsuallyEffective

Wet fluorescent magneticparticle testing of 10-24% ofweldments; or Dry magneticparticle testing of 25-100% ofweldments; or Dye penetranttesting of 25-100% ofweldments.

Shear wave ultrasonic testing of 10-24% of weldments; Radiographictesting of 50-100% of weldments.

C Fairly Effective

Wet fluorescent magneticparticle testing of less than 10%of weldments; or Dry magneticparticle testing of less than 25%of weldments; or Dye penetranttesting of less than 25% ofweldments.

Shear wave ultrasonic testing of lessthan 10% of weldments; Radiographictesting of 20-49% of weldments.

DPoorly

EffectiveVisual inspection Radiographic testing of less than 20%

of weldments.

E Ineffective No inspection No inspection


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2-22

10 SCC DAMAGE FACTOR HIC/SOHIC-H2

10.1 Scope

S



10.4 Required Data



10.6.1 Overview




Inspections are ranked according to their expected effectiveness at detect