asme api 579 si handouts

API 579-1/ASME FFS-1 (2007)

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Document version 2011/01/v1.4 Last update - 21 Sept 2011

API 579-1/ASME FFS-1 FITNESS-FOR-SERVICE OF PIPING, VESSELS AND TANKS Ron Frend 1

API 579-1/ASME FFS-1

Fitness for Service

of Piping, Vessels and Tanks


API 579-1/ASME FFS-1 FITNESS-FOR-SERVICE OF PIPING, VESSELS AND TANKS Ron Frend

Daily Schedule

08:30 10:00 1st Session

10:00 1045 Coffee Break

10:45 12:30 2nd Session

12:30 13:30 Lunch

13:30 15:00 3rd Session

15:00 15:45 Coffee Break

15:45 17:00 Open session

In order to ensure the smooth running of the Seminar, it is extremely important that daily timings are strictly adhered to.

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Document version 2011/01/v1.4 Last update - 21 Sept 2011 3

PROGRAMME OBJECTIVES Understand FFS for static, mechanical equipment

Balanced fundamental technical principles with a practical application to field conditions

See how ASME codes apply to FFS

Use ASME and API rules to assess remaining life

Apply practical examples to analyze conditions

Apply the step-by-step 3-level approach

Understand risk-based evaluation of remaining life.

Evaluate structural integrity and assess remaining life.



Programme DAY 1 FOUNDATIONS OF FITNESS-FOR-SERVICE ASSESSMENT

Introduction to Fitness For Service Assessment

ASME Construction Codes

PART 3 Brittle Fracture PART 4 General Metal Loss `

DAY 2 MECHANICAL INTEGRITY AND FITNESS FOR SERVICE PART 5 Local Metal Loss ANNEX A Thickness, MAWP & Stress equations for a FFS Assessment PART 6 Pitting Corrosion PART 7 Hydrogen Blisters, HIC & SOHIC

DAY 3 PITTING & CORROSION PART 8 Weld Misalignment & Shell Distortions PART 9 Cracks & Crack-Like Flaws PART 10 Creep PART 11 Fire Damage

DAY 4 FIRE & MECHANICAL DAMAGE

PART 12 Dents & Gouges PART 13 Laminations Overview & Wrap Up

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Ron Frend - Profile

Ronald Frend M.Sc.

Shell Tankers (UK) Ltd

1970 1984

Marine Engineer Certified Chief Engineer

Petroleum Development (Oman)

1984 1989

Mechanical Equipment Supervisor

Head of Maintenance Planning

Head of Surface Support (North Oman)

Private Consultant

1989 present

Petro-Chem, Manufacturing, Shipping, Process




A Joint API/ASME Standard for the evaluation of the

Fitness of Equipment to

remain in service while

suffering various types of

damage or code violation.

This standard is based on

STRENGTH

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What is FFS? ASME and API codes for pressurized equipment do not

address in-service equipment degradation nor deficiencies in original fabrication.

These codes do not permit crack-like flaws, have empirical rules used for acceptance of metal loss, and provide minimum guidance on the acceptability of other flaws and damage types (for example, blisters, creep, and fire damage).



What is FFS?

An FFS assessment is an engineering analysis of equipment to determine whether it is fit for continued service.

The equipment may contain flaws, may not meet current design standards, or may be subject to more severe operating conditions than the design conditions.

The product of an FFS assessment is a decision to operate the equipment as is, or to alter, repair, monitor, or replace the equipment.

API 579-1/ASME FFS-1 also provides guidance on appropriate inspection intervals.

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API 579-1/ASME FFS-1 FFS

API 579-1/ASME FFS-1 supplements the requirements in API 510, API 570, and API 653.

API 579 has three functions:

1. To ensure safety of plant personnel and the public while older equipment continues to operate.

2. To provide technically sound FFS assessment procedures to ensure that different service providers furnish consistent life predictions.

3. To help optimize maintenance and operation of existing facilities to maintain availability of older plants and enhance long-term economic viability.



Continue In Service?

The following questions are frequently asked regarding the mechanical integrity of the equipment in question:

"Can this equipment be put back in service without repair?"

"How long can this equipment be kept in service?"

"Can the repair work be deferred to the next scheduled turnaround maintenance time?"

"What would be the consequence when the damage propagates if not repaired?"

"What would be the most effective way to detect and monitor the damage?"

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FFS assessments

can be used at any stage of the life of a structure:

In the concept and design phase, material property requirements can be set.

In the construction phase

During routine inspection.

Towards the end of the design life of a structure.



FFS Assessment

A "fitness-for-service" (FFS) assessment demonstrates that failure of the defective component will not occur by any recognized failure mechanism within a reasonable time.

Such FFS analyses typically involve stress analysis,

fracture mechanics,

material testing and

quantitative NDT measurements, in addition to

the operating conditions.

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Technical Integrity Plan: Risk Reliability Management

Asset Register

Action: Preventive Maintenance

Corrective Maintenance

Inspection

Operation

Check: Deviation Control

Technical Authorities

Risk Management

Analyse: Root Cause Analysis

Fitness for Purpose

Improve: Change Management

Modification Projects

Specifications

Procedures

Standards

Specifications

Procedures

Standards



Introduction

2000 - The first edition of API 579 produced by API CRE FFS Task Group becomes the de facto international Fitness-For-Service (FFS) Standard for pressure containing equipment in the refining and petrochemical industries

ASME forms Post Construction Committee (PCC) to develop standards for in-service fixed equipment

API and ASME agreed to form a joint committee to produce a single FFS standard that can be used for pressure-containing equipment for all industries published in 2007.

CRE Committee on Refinery Equipment

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New Joint API and ASME FFS Standard

API 579 forms basis of joint API/ASME standard produced by the

API/ASME joint committee

API 579-1/ASME FFS-1 2007 supersedes API 579-2000

API 579-1/ASME FFS-1 2007 standard includes all previous topics and

also includes new parts covering FFS assessment procedures that

addresses unique damage mechanisms experienced by other industries



Overview of API 579-1/ASME FFS-1 Sections have been renamed to Parts and

Appendices to Annexes

New Enhancements Existing Sections and New Parts Part 5 - Assessment of Local Thin Areas, assessment procedures for

gouges have been relocated to Part 12

Part 7 - Assessment of Blisters and HIC/SOHIC Damage, assessment

procedures for HIC/SOHIC damage have been added

Part 8 - Assessment of Weld Misalignment and Bulges, assessment

procedures for bulges removed, assessment procedures for dents,

gouges, and dent-gouge combinations have been relocated to Part 12

Part 10 - Assessment of Equipment Operating in the Creep Range,

assessment procedures for remaining life calculations for components

with or without crack-like flaws have been added

Part 12 - Assessment of Dents, Gouges, and Dent-Gouge Combinations,

new Part

Part 13 - Assessment of Laminations, new Part

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New Enhancements Existing and New Annexes

Annex B - Stress Analysis Overview for a FFS Assessment, complete

rewrite to incorporate new elastic-plastic analysis methods and fatigue

evaluation technology developed for the ASME Div 2 Re-write Project,

Structural Stress/Master S-N Approach will be included

Annex C - Compendium of Stress Intensity Factor Solutions, new stress

intensity factor solutions for thick wall cylinders, through wall cracks in

cylinders and spheres, holes in plates

Annex E - Compendium of Residual Stress Solutions, complete rewrite to

incorporate new solutions developed by PVRC Joint Industry Project

Annex F - Material Properties for a FFS Assessment, new stress-strain

curve model incorporated

Annex H - Technical Basis and Validation of FFS Procedures

Annex K - Crack Opening Areas, new annex covering crack opening areas

for through-wall flaws in cylinders and spheres

Overview of API 579-1/ASME FFS-1




Organization of Parts Part 1 Introduction

Part 2 FFS Engineering Evaluation Procedure

Part 3 Assessment of Equipment for Brittle Fracture

Part 4 Assessment of General Metal Loss (tm < tmin - large area)

Part 5 Assessment of Localized Metal Loss (tm < tmin - small area)

Part 6 Assessment of Pitting Corrosion

Part 7 Assessment Of Hydrogen Blisters and Hydrogen Damage Associated with HIC and SOHIC

Part 8 Assessment of Weld Misalignment and Shell Distortions

Part 9 Assessment of Crack-Like Flaws

Part 10 Assessment of Equipment Operating in the Creep Regime

Part 11 Assessment of Fire Damage

Part 12 Assessment of Dents, Gouges, and Dent-Gouge Combinations

Part 13 Assessment of Laminations

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Organization of Annexes

Annex A Thickness, MAWP, and Stress Equations for a FFS Assessment

Annex B Stress Analysis Overview for a FFS Assessment

Annex C Compendium of Stress Intensity Factor Solutions

Annex D Compendium of Reference Stress Solutions

Annex E Residual Stresses in a FFS Evaluation

Annex F Material Properties for a FFS Assessment

Annex G Deterioration and Failure Modes

Annex H Validation

Annex I Glossary of Terms and Definitions

Annex J Currently Not Used

Annex K Crack Opening Areas




Covers equipment constructed to ASME B&PV Section VIII, Div 1

ASME B&PV Section VIII, Div 2

B31.3, Process Piping

B31.1, Power Piping

API 650

API 620

It can also be used with equipment constructed to other recognized standards

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FFS Methods

Based on a variety of the American and British codes and standards, such as

ASME Pressure Vessel and Boiler Code Section XI,

ASME/ANSI B31.G, Modified B31.G (also known as "RSTRENG" method),

BSI PD 6493 (now BS 7910) and




FFS assessments

Part of the plant life management process as a means of increasing

Availability

Reliability

Efficiency and

Safety.

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FFS Requirements

Require an interdisciplinary approach with operations personnel consisting of an understanding of

Damage mechanisms and material behaviour.

Past and future operating conditions.

Non-destructive examination techniques (flaw location and sizing).

Material properties (environmental effects).

Stress analysis (finite element analysis; FEA) and

Data analysis (engineering reliability models).



In-service damage mechanisms

Damage to a component can occur in many forms such as:

Mechanical damage

Overload

Overheating

Corrosion

Erosion

Fatigue

Creep and

Hydrogen

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Damage Mechanisms

Regardless what materials in what process conditions, the symptoms of corrosion damage normally exhibit in the following forms:

Uniform metal loss or wall thinning due to general attack;

Local wall thinning due to localized attack;

Surface breaking cracks;

Embedded cracks under metal surfaces and

Metallurgical change or materials property change.



4 primary defect categories

Metal Loss Crack-like flaws

Geometrical defects

Metallurgical flaws

General (uniform) corrosion

Fatigue Cracks Dents Toughness reduction

Crevice corrosion SCC Gouges Strength reduction

Pitting corrosion Planar fabrication flaws

Out-of-roundness Corrosion resistance reduction

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Other codes

When evaluating other codes and standards

the following should be considered:

Material specifications

Upper and/or lower temperature limits for specific materials

Material strength properties & design allowable stress basis

Material fracture toughness requirements

Design rules for shell sections

Design rules for shell discontinuities such as nozzles

Design requirements for cyclic loads.

Design requirements for operation in the creep range

Weld joint efficiency or quality factors

Fabrication details and quality of workmanship

Inspection requirements, particularly for welded joints



Other codes (contd)

Material may be correlated to equivalent ASME or API specification.

May then apply the acceptance limits of these fitness for service procedures unaltered.

User is cautioned to also consider the effects of fabrication and inspection requirements on the design basis (e.g. joint efficiency with respect to minimum thickness sizing).

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Covers present integrity of the component given a current state of damage and the projected remaining life

Flaw evaluation general and localized corrosion

widespread and localized pitting

blisters and laminations

weld misalignment and shell distortions

crack-like flaws including environmental cracking

to brittle fracture

long-term creep damage

fire damage


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API 579 PART 2

FITNESS-FOR-SERVICE

ENGINEERING

ASSESSMENT

PROCEDURE

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What is API 579-1/ASME FFS-1?

API 579, first released in 2000, is a recommended practice for fitness-for-service that combines 10 years of effort by the leading petrochemical companies.

It gives engineers and technicians the tools needed to make run-or-repair decision for corroded and damaged equipment.



What API 579 is not ...

It does not predict how the

degradation will progress.

It evaluates the current

condition or a projected

future condition.

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covers situations involving flaws commonly

encountered in the refining and petrochemical

industry in

pressure vessels,

piping and

tankage.




The procedures are NOT intended to provide a definitive

guideline for every possible situation that may be

encountered.

flexibility is provided to the user in the form of an advanced

assessment level to handle uncommon situations that may

require a more detailed analysis

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The assessment procedures are based on allowable stress

methods and plastic collapse loads for non-crack-like flaws,

and FAD-based (Failure assessment diagram ) strategies for crack-like flaws

Enables user to factor, scale, or adjust the acceptance limits

such that equivalent FFS in-service margins can be attained

for equipment not constructed to these codes.



Who is involved in fitness-for-

service?

Fitness-for-service, API 579, is multi-discipline:

Materials engineer

Designer (stress analysis)

System engineer

Inspector

Operator

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Is fitness-for-service a qualitative

method based on judgment?

A lot of experience has

been compiled in the

document, but it is

primarily a quantitative

method.



How is the standard structured?

A part for each degradation mechanism.

Each part has three levels of evaluation:

Level 1 Evaluation in the field

Level 2 Evaluation in engineering office

Level 3 Expert evaluation

The standard is self-contained

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Three Levels of Evaluation

Provided for each flaw

Level 1 - Evaluation simplified to charts and simple

formulae, generally simplified by conservative

assumptions

Level 2 - Generally requires more detailed evaluation;

more accurate

Level 3 - Allows for flaw assessment by more

sophisticated methods



Typical Level 1 Limitations

Original design in accordance with a recognized code or standard

Equipment is not operating in the creep range

Equipment is not in cyclic service (fatigue)

Thickness governed by pressure so equations relate required thickness to pressure

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Level 2 Assessment

Includes components requiring more

complex calculations such as nozzles

and flanges

Includes consideration of supplemental

loads

Includes evaluation of piping systems



PROCEDURE

1 - Damage mechanism

2 - Applicability

3 - Input data

4 - Analysis

5 - Remaining life prediction

6 - Remediation and repair

7 - In-service monitoring

8 - Documentation

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FFS Assessment Steps Stage Description

1 Flaw and damage mechanism identification.

The first step in a fitness-for-service assessment is to identify the flaw type and cause of damage. The original design and fabrication practices, the material of construction, and the service history and environmental conditions help to ascertain the likely cause of the damage.

2 Applicability and limitations of the FFS assessment procedures.

A description of the applicability and limitations of the assessment procedure help the operator to decide whether or not to proceed with an assessment.

3 Data requirements.

The flaw type or damage mechanism determines the data required. Data requirements may include original equipment design data, information pertaining to maintenance and operational history, expected future service, and data specific to the FFS assessment.

4 Assessment techniques and acceptance criteria.

Each section of the code provides assessment techniques and acceptance criteria. If multiple damage mechanisms are pre-sent, more than one section apply to the evaluation.

5 Remaining life evaluation. FFS assessment procedures help estimate the remaining life or limiting flaw size to establish an inspection interval.

6 Remediation.

Each section of the code provides remediation methods based on the damage mechanism or flaw type. Remediation techniques may control future damage associated with flaw growth or material degradation.

7 In-service monitoring.

Each section of the code provides methods for in-service monitoring based on the damage mechanism or flaw type. In-service monitoring may be used for those cases in which a remaining life and inspection interval cannot adequately be established.

8 Documentation.

Documentation should include a record of all information and decisions made in each of the previous steps to qualify the component for continued operation.



REMAINING STRENGTH FACTOR RSF

Remaining strength factor RSF

RSF = LDC / LUC

LDC = limit load (pressure, force, moment) of damaged component

LUC = limit load of undamaged component

Component is acceptable if

RSF > RSFa

RSFa = allowable remaining strength factor = 0.7 to 0.9

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Overview of an

FFS Analysis for

Crack-Like Flaws

Using the

Failure Assessment Diagram



Flaw or damage - Section mechanism Overview 3.0 Brittle fracture Provides assessment procedures for evaluating the resistance to brittle fracture of existing carbon and low alloy steel pressure

vessels, piping, and storage tanks. Provides criteria to evaluate normal operating, start-up, upset, and shut-down conditions.

4.0 General metal loss Provides assessment procedures to evaluate general corrosion. Allows either point thickness readings or detailed thickness profiles for thickness data. Provides a methodology to use the assessment procedures of Section 5.0 when the thickness data indicates that the metal loss can

be treated as localized.

5.0 Local metal loss Provides assessment techniques to evaluate single and networks of local thin areas and groove-like flaws in pressurized components.

Requires detailed thickness profiles for the assessment. Can evaluate blisters.

6.0 Pitting corrosion Provides assessment procedures to evaluate widely scattered pitting, localized pitting, pitting which occurs within a region of local metal loss, and a region of localized metal loss located within a region of widely scattered pitting.

Can evaluate a network of closely spaced blisters.

7.0 Blisters, HIC & SOHIC assessment procedures are provided in this Part for low strength ferritic steel pressurized components with hydrogen induced cracking (HIC) and blisters, and stress oriented HIC (SOHIC) damage

8.0 Weld misalignment and shell distortions

Provides assessment procedures to evaluate stresses resulting from geometric discontinuities in shell type structures including weld misalignment and shell distortions (for example, out-of-roundness, bulges and dents).

9.0 Crack-like flaws Provides assessment procedures to evaluate crack-like flaws. Covers recommendations for evaluating crack growth, including environmental concerns.

10.0 High temperature operation and creep

Provides assessment procedures to determine the remaining life of a component operating in the creep regime. Covers recommendations for evaluating crack growth including environmental concerns.

11.0 Fire damage Provides assessment procedures to evaluate equipment subject to fire damage. Provides a methodology to rank and screen components for evaluation based on the heat exposure experienced during the fire. Refers to assessment procedures in the other sections of this publication to evaluate component damage.

12.0 Dents & Gouges Procedures for pressurized components containing dents, gouges, or dent-gouge combinations resulting from mechanical damage. The procedures can be used to qualify a component for continued operation or for determining a reduced maximum allowable working pressure

13.0 Laminations Assessment procedures for pressurized components with laminations, excluding HIC or SOHIC damage

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Sensitivity Analysis

Consider different assumptions with regard to loading conditions,

material properties and

flaw sizes

Demonstrate that small changes in input parameters do not dramatically change the assessment results

If a strong dependence on an input variable is found, improve the degree of accuracy used to establish the value of that variable



Probabilistic Analysis

Evaluate dependence of safety margin on uncertainty of independent variables

Estimate failure probability using Monte Carlo simulation,

First order reliability methods

Or other analytical techniques,

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Remaining Life Assessment

Remaining life estimates will fall into one of three general categories

The Remaining Life Can be Calculated With Reasonable Certainty Good history & accurate modelling

The Remaining Life Cannot be Established With Reasonable Certainty e.g. SCC

Ensure remediation is effective

There is Little or No Remaining Life Remediation and/or frequent monitoring



REMAINING LIFE

Remaining life for general metal loss

Rlife = remaining life, years

tam = averaged measured wall, in

tmin = minimum code required wall, in

Crate = corrosion rate, in/year

rate

minam

life

C

ttR

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Documentation

The equipment design data, and maintenance and past operational history to the extent available should be documented for all equipment subject to a FFS assessment.

Inspection data including all readings utilized in the FFS assessment.

Assumptions and analysis results including:

1. Part, edition, and assessment level of this Standard and any other supporting

documents used to evaluate the flaw or damage.

2. Future operating and design conditions including pressure, temperature and

abnormal operating conditions.

3. Calculations of the minimum required thickness and/or MAWP.

4. Calculations of remaining life and the time for the next inspection.

5. Any remediation or mitigation/monitoring recommendations that are a condition for

continued service.

Brittle

Fracture


52

API

Codes, Standards &

Recommended Practices

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API Background

1924 first standard released (interchangeability of oil field equipment )

Today, over 1000 API standards serve as the basis for API quality programs covering production material and lubricants, and certification programs for storage tanks, pressure vessels, and piping inspectors.

Based in Washington, D.C. with offices in 27 state capitals



API History

Origin during World War I, when Congress and the domestic oil and natural gas industry worked together to help the war effort.

1911 - court-imposed dissolution of Standard Oil and the "independents." These companies had no experience working together, but they agreed to work with the government to ensure that vital petroleum supplies were rapidly and efficiently deployed to the armed forces.

The National Petroleum War Service Committee, which oversaw this effort, was initially formed under the U.S. Chamber of Commerce and subsequently as a quasi-governmental body.

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56

ASME Construction Codes

Boiler & Pressure Vessel Code

B31 Codes for Piping & Pipelines

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ASME

American Society of Mechanical Engineers was founded in 1880 now >100,000 members

Programmes include education,

technical conferences and exhibits

government relations

public education



ASME's Boiler and Pressure Vessel Code

More than 2,000 boilers exploded from 1880 to 1890.

Although numerous boiler failures in the late 19th century, there were no legal codes for boilers in the USA

Code for the Conduct of Trials of Steam Boilers was ASMEs first standard, and set in motion 125 years of codes and standards development.

more than 1,500 died when a boiler exploded on

the overloaded steamboat Sultana in 1865.

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Boiler failure in Brockton, Mass., on March 10, 1905, at the Brockton Shoe Factory resulted in 58 deaths and 117 injuries, and completely levelled the factory.

1906 - Massachusetts in 1906 established a five-man Board of Boiler Rules, whose charge was to write a boiler law for the state; this board published its boiler laws in 1908.

1911 - the ASME Council appointed a committee to formulate a boiler code,




The first Boiler and Pressure Vessel Code was published in 1915; as a 114-page book, measuring 5 x 8 inches.

Today there are 28 books, including a dozen dedicated to the construction and in service inspection of nuclear power plant components, and two Code Case Books.

The Boiler and Pressure Vessel Code contains more than 14,000 pages, each of which measures 81/2 by 11 inches; it occupies 12 feet of shelf space.

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ASME Boiler & Pressure Vessel Code

Individual Volumes

I - Power Boilers

II - Materials

III - Rules for Construction of Nuclear Power Plant Components

IV - Heating Boilers

V - Nondestructive Examination

VI - Recommended Rules for the Care and Operation of Heating Boilers

VII - Recommended Guidelines for the Care of Power Boilers

VIII - Pressure Vessels

IX - Welding and Brazing Qualifications

X - Fiber-Reinforced Plastic Pressure Vessels

XI - Rules for Inservice Inspection of Nuclear Power Plant Components

XII - Rules for Construction and Continued Service of Transport Tanks



ASME B&PV Volume VIII

Division 1 design, fabrication, inspection, testing, and certification of fired or

unfired pressure vessels operating at either internal or external pressures exceeding 15 psig. (no max)

Division 2 alternative (more rigorous) to the minimum requirements for

pressure vessels under Division 1 rules (no max)

Division 3 design, fabrication, inspection, testing, and certification of fired or

unfired pressure vessels operating at either internal or external pressures generally above 10,000 psi. (no minimum)

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ASME B31 CODES



ASME B31 CODES

Power Piping - ASME B31.1

Process Piping - ASME B31.3

Liquid Petroleum Transportation Piping - ASME B31.4

Refrigeration piping - ASME B31.5

Gas Transmission and Distribution Piping - ASME B31.8

Building Services Piping - ASME B31.9

Slurry Transportation Piping - ASME B31.11

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What is our objective?

To introduce engineers and technicians to the application of API 579, through practical exercises.

The participants will apply API 579 to evaluate the integrity and remaining life of corroded, cracked, or damaged tanks, vessels, piping systems and pipelines.

It is a quantitative technique. YOU NEED A LAPTOP WITH MS-EXCEL or equivalent



Cant I use the existing codes, ASME, to evaluate the integrity of operating equipment?

The design codes contain acceptance criteria for fabrication flaws,

not for degradation in service.

ASME VIII pressure vessels

ASME B31.3 process piping

ASME B31.4 oil pipeline

ASME B31.8 gas pipeline

API 653 storage tanks

Note: ASME B31.4 and ASME B31.8 include rules for the evaluation

of local corroded areas, based on 1970s ASME B31.G.

Note: NBIC NB-23 contains simple rules for evaluation of corrosion.

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Is fitness-for-service a code?

With the new release in 2007 API 579

Fitness-for-Service is a STANDARD.

It combines in one place many references

and companies procedures.



Are there other standards for fitness-for-

service?

API 1104 Ap. A (Alaskan pipeline, 1970s)

ASME B31G for oil and gas pipelines

Canadian Standard Association CSA Z662 Ap. K (earlier CSA Z184, 1986)

DVS Guidelines 2401, Germany, 1996

European Pipeline Research Group EPRG Guidelines (1993 first published)

SINTAP (Structural Integrity Assessment Procedures for European Industry)

PrEN 13445-3, 1998 Fatigue verification of welded joints, European

British Standard Institute BSI PD 6493:1991, replaced by BS7910:1999 (TWI)

Australian Standard AS 2885.2-1995, similar to EPRG, Pipesafe software.

ASME B&PV code Section XI for US nuclear power

British standard R6 for UK nuclear power

NASA Nasgro software (SWRI, Boeing)

SQA/FoU report 96/08, Sweden

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69

API 579 APPENDIX A

THICKNESS - MAWP - STRESS EQUATIONS



STRESS DISTRIBUTION

Normal and shear stress at a point.

API 579-1/ASME FFS-1 (2007)

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pt 36



BASIC EQUATION

CYLINDRICAL SHELL

Hoop (circumferential) stress

Longitudinal (axial) stress

t

PR

t2

PDhoop

t2

PR

t4

PDaxial



EXERCISE HOOP STRESS

A pressure vessel has a diameter of 1300mm and a wall thickness of 10mm. It operates at 2000kPa.

What is the hoop stress in the cylindrical shell? What is the longitudinal stress?

API 579-1/ASME FFS-1 (2007)

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pt 37



OVERPRESSURE FAILURE



API 579 APPENDIX A

THICKNESS - MAWP - STRESS EQUATIONS

Cylindrical shells, thickness for circumferential stress,

pressure only (ASME VIII, UG-27)

tmin = minimum wall of the cylindrical shell, in

P = design pressure, psi

R = inside radius, in

S = allowable stress, psi

E = weld joint efficiency factor

)P6.0SE(

PRt

min

API 579-1/ASME FFS-1 (2007)

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pt 38



EXERCISE ASME VIII SHELL

P = 690 kPa

S = 121 MPa SA 515-70 plate @ 343oC

E = 0.85 (spot examination)

R = 1219mm

What is the ASME VIII Div.1 required wall thickness of the cylindrical shell?



CYLINDRICAL SHELLS

Weld Type 100% RT Spot RT No RT

Double ButtOr equivalent

1.00 0.85 0.70

Single Butt(with backing

strip)

0.90 0.80 0.65

Single Butt(no backing strip)

- - 0.60

Double Fillet Lap - - 0.55

Single Fillet LapWith plug welds

- - 0.50

Single Fillet lapNo plug welds

- - 0.45

API 579-1/ASME FFS-1 (2007)

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pt 39



SPHERICAL HEAD



SPHERICAL HEAD

Spherical or hemispherical head (ASME VIII, UG-27)

tmin = minimum wall of head, in


L = inside radius, in



E

Hemi. head 100% RT Spot RT No RT

Type 1 1.00 0.85 0.70

Type 2 0.90 0.80 0.65

)2.02(min

PSE

PLt

API 579-1/ASME FFS-1 (2007)

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pt 40



EXERCISE - ASME VIII

SPHERICAL HEAD

P = 690 kPa

S = 121 MPa psi SA 515-70 plate @ 343oC

E = 0.85 (spot examination)

R = 1219mm

What is the ASME VIII Div.1 required wall thickness of the spherical head?



ELLIPSOIDAL HEAD

API 579-1/ASME FFS-1 (2007)

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pt 41



ELLIPSOIDAL HEAD



ELLIPSOIDAL HEAD

Elliptical head (ASME VIII, Ap.I)



RC = inside radius, in



K = (2 + Rell2) / 6

Rell = ratio of major-to-minor axis of

elliptical head = B/A = 2 for 2:1

head (B= 2, A = 1).

)2.0(2

)(min

PSE

KPDt

API 579-1/ASME FFS-1 (2007)

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pt 42



ELLIPSOIDAL HEAD E

Head 100% RT Spot RT No RT

Other than hemi. 1.00 1.00 0.85



EXERCISE -

ELLIPSOIDAL HEAD

P = 690kPa

S = 121MPa SA 515-70

plate @ 343oC

E = 1.0

R = 1219mm

What is the ASME VIII

Div.1 required wall

thickness of the

2:1ellipsoidal head?

API 579-1/ASME FFS-1 (2007)

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pt 43



TORISPHERICAL HEAD

(FLANGED AND DISHED HEAD)



TORISPHERICAL HEAD

Torispherical head

[Flanged and dished]

(ASME VIII Ap.I)



L = inside crown radius, in



PSE

PLt

1.02

885.0min

For t/L 0.002

API 579-1/ASME FFS-1 (2007)

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pt 44



EXERCISE - ASME VIII

TORISPHERICAL HEAD

P = 690 kPa

S = 121 Mpa SA 515-70 plate

@ 343oC

E = 1.0 (seamless)

R = 1219mm

What is the ASME VIII Div.1

required wall thickness of the

torispherical head with L/r =

16.66?



FLAT HEAD

API 579-1/ASME FFS-1 (2007)

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pt 45



FLAT HEADS

Flat Heads

t = minimum wall thickness

tr = minimum required thickness of

seamless shell

tS = actual thickness of shell, exclusive

of corrosion allowance

S = maximum allowable stress, psi


SE

CPdt



EXERCISE ASME VIII FLAT HEAD

P = 690 kPa

S = 121 MPaSA 515-70 plate @ 343oC

E = 1.0 (seamless)

R = 1219mm

What is the ASME VIII Div.1 required wall thickness of the flat head?

API 579-1/ASME FFS-1 (2007)

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pt 46



EXERCISE - FLAT HEAD

A heat exchanger has a design

pressure (Maximum Allowable

Working Pressure MAWP) of

2414 kPa at 205oC

It has a 0.915m diameter, and

the allowable stress is 124MPa.

The flat head is seamless.

What is the ASME VIII Div.1

minimum thickness of the flat

head?



EXERCISE

Pressure vessel

Design pressure = 2068 kPa

Design temperature = 177oC

Inside diameter = 1220 mm

Corrosion allowance = 2.5 mm

Material = SA 516 Grade 70

Weld joint efficiency = 0.85

What is the minimum wall thickness of the cylindrical shell?

Thickness of ellipsoidal head?

API 579-1/ASME FFS-1 (2007)

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pt 47



PIPING SYSTEMS

ASME B31.1 - ASME B31.3





D = outside diameter, in

W = longitudinal weld joint efficiency factor

t =wall thickness, in

)(2 PySEW

PDt

API 579-1/ASME FFS-1 (2007)

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pt 48




Values of W

Seamless = 1.0

Furnace butt weld = 0.6

Electric fusion arc weld = 0.8

Electric resistance weld = 1.0

Double submerged arc weld = 1.0

Values of y

T < 900oF = 0.4



EXERCISE ASME B31.3 PIPING

P = 690kPa

S = 121 MPa carbon steel pipe @ 343oC

W = 1.0 (seamless)

Pipe = 10 Sched 40 (254mm OD)

What is the B31.3 required pipe wall thickness?

API 579-1/ASME FFS-1 (2007)

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pt 49



Nominal Pipe

Size Outside

Diameter, in.

Schedule Number Wall

Thickness (in)

Inside

Diameter (in)

Weight per

ft (lb)

Weight of

water per ft

(lb)

Moment of

Inertia (in4)

Section Modulus

(in3)

a b c

1/8 - - 10S 0.049 0.307 0.2 0.03 0.0009 0.0044

0.405 40 Std 40S 0.068 0.269 0.2 0.02 0.0011 0.0053

80 XS 80S 0.095 0.215 0.3 0.02 0.0012 0.0060

1/4 - - 10S 0.065 0.410 0.3 0.06 0.0028 0.0103

0.540 40 Std 40S 0.088 0.364 0.4 0.05 0.0033 0.0123

80 XS 80S 0.119 0.302 1.1 0.03 0.0114 0.0325

3/8 - - 10S 0.065 0.545 0.4 0.10 0.0059 0.0174

0.675 40 Std 40S 0.091 0.493 0.6 0.08 0.0073 0.0216

80 XS 80S 0.126 0.423 0.7 0.06 0.0086 0.0255

1/2 - - 10S 0.083 0.674 0.7 0.15 0.0143 0.0341

0.840 40 Std 40S 0.109 0.622 0.9 0.13 0.0171 0.0407

80 XS 80S 0.147 0.546 1.1 0.10 0.0201 0.0478

160 - - 0.187 0.466 1.3 0.07 0.0221 0.0527

- XXS - 0.294 0.252 1.7 0.02 0.0242 0.0577

3/4 - - 5S 0.065 0.920 0.7 0.29 0.0245 0.0467

1.050 - - 10S 0.083 0.884 0.9 0.27 0.0297 0.0566

40 Std 40S 0.113 0.824 1.1 0.23 0.0370 0.0706

80 XS 80S 0.154 0.742 1.5 0.19 0.0448 0.0853

160 - - 0.218 0.614 1.9 0.13 0.0527 0.1004

- XXS - 0.308 0.434 2.4 0.06 0.0579 0.1104

1 - - 5S 0.065 1.185 0.9 0.48 0.0500 0.0760

1.315 - - 10S 0.109 1.097 1.4 0.41 0.0757 0.1152

40 Std 40S 0.133 1.049 1.7 0.37 0.0874 0.1329

80 XS 80S 0.179 0.957 2.2 0.31 0.1056 0.1607

160 - - 0.250 0.815 2.8 0.23 0.1252 0.1904

- XXS - 0.358 0.599 3.7 0.12 0.1405 0.2137

1-1/4 - - 5S 0.065 1.530 1.1 0.80 0.1038 0.1250

1.660 - - 10S 0.109 1.442 1.8 0.71 0.1605 0.1934

40 Std 40S 0.140 1.380 2.3 0.65 0.1948 0.2347

80 XS 80S 0.191 1.278 3.0 0.56 0.2419 0.2914

160 - - 0.250 1.160 3.8 0.46 0.2839 0.3421

- XXS - 0.382 0.896 5.2 0.27 0.3412 0.4111

1-1/2 - - 5S 0.065 1.770 1.3 1.07 0.1580 0.1663

1.900 - - 10S 0.109 1.682 2.1 0.96 0.2469 0.2599

40 Std 40S 0.145 1.610 2.7 0.88 0.3100 0.3263

80 XS 80S 0.200 1.500 3.6 0.77 0.3913 0.4119

160 - - 0.281 1.338 4.9 0.61 0.4825 0.5079

- XXS - 0.400 0.950 5.8 0.31 0.4205 0.4806

2 - - 5S 0.065 2.245 1.6 1.72 0.3150 0.2652

2.375 - - 10S 0.109 2.157 2.6 1.58 0.4993 0.4205

40 Std 40S 0.154 2.067 3.7 1.45 0.6659 0.5608

80 XS 80S 0.218 1.939 5.0 1.28 0.8681 0.7311

160 - - 0.343 1.689 7.4 0.97 1.1626 0.9790

- XXS - 0.436 1.503 9.0 0.77 1.3116 1.1045



LONGITUDINAL STRESS IN

PIPING SYSTEM

Weight, expansion, wind, waves, vibration, etc. bend the pipe. This causes a longitudinal bending stress.

API 579-1/ASME FFS-1 (2007)

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pt 50




PIPING SYSTEM The bending stress due to a bending moment M is

Exercise:

The bending moment due to weight is

M = wL2/10

M = maximum bending moment, in-lb

w = weight per unit length, lb/in

L = span length, in

What is the maximum bending stress in the pipe span of a 6 sch.40 pipe full of water? (use i=1)

Z

Mi75.0S

bending



ASME B31.4

OIL - LIQUID PRODUCTS PIPELINES

API 579-1/ASME FFS-1 (2007)

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pt 51



ASME B31.4 - OIL PIPELINES

B31.4

S = 0.72 E Sy


D = outside diameter, in

E = longitudinal weld joint efficiency factor

Sy = minimum specified yield stress (MSYS), psi

S2

PDt



EXERCISE OIL PIPELINE B31.4

P = 4826 kPa at 30oC

D = 500 mm

ERW longitudinal weld E = 1.0

API 5L X42 SY = 42000 psi

(289.6MPa)

What is the minimum wall

thickness required by ASME

B31.4?

API 579-1/ASME FFS-1 (2007)

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pt 52




PIPELINE

Soil settlement causes a pipeline to bend down 6 over 100 ft. Pipe is 24 x 0.5 w.t. (D = 24, d = 23) X52 (SMYS = 52 ksi)

ksiksiksiksiS

ksix

psi

t

PDS

ksiL

ES

ksipsi

L

EDs

TOTALALLONGITUDIN

PALLONGITUDIN

ALLONGITUDIN

BENDING

4.404.14224

4.14"5.04

"241200

4

2"1200

"6)1030(

3

8

3

8

24)"1200(

"6"24)1030(88

,

,

2

6

2

,

2

6

2



ASME B31.8

GAS PIPELINE

API 579-1/ASME FFS-1 (2007)

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pt 53



ASME B31.8 - GAS PIPELINE

S = FET Sy

Values of F

Location class 1, wasteland, desert, mountains, etc. F = 0.72 or 0.8

Location class 2, 10 to 46 buildings within 1 mile, industrial area, F = 0.6

Location class 3, suburbs, F = 0.5

Location class 4, city, F = 0.4

Values of T

T < 250oF T = 1.0

T < 300oF T = 0.967

T < 350oF T = 0.933

T < 400oF T = 0.900

T < 450oF T = 0.867

S2

PDt



EXERCISE GAS PIPELINE B31.8

P = 4826 kPa at 30oC

D = 500 mm

ERW longitudinal weld E = 1.0

API 5L X42 SY = 42000 psi

(289.6MPa)

What is the minimum wall

thickness required by ASME

B31.8?

API 579-1/ASME FFS-1 (2007)

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pt 54



API 579

FITNESS-FOR-SERVICE


108

Brittle Fracture

API 579-1/ASME FFS-1 (2007)

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pt 55



API 579 PART 3

ASSESSMENT OF EXISTING

EQUIPMENT FOR BRITTLE FRACTURE



API 579/ASME FFS PART 3

ASSESSMENT OF EXISTING

EQUIPMENT FOR BRITTLE FRACTURE

API 579-1/ASME FFS-1 (2007)

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pt 56



What is Brittle Fracture?

WWII Merchant Ships Etc.

Over 250 ships fractured or cracked. 19 broke completely in two! Steel not tough enough.

The Great Boston Molasses Tank Disaster

1919. Tank 90 ft diameter and 50 feet high. When the tank split, a wall of molasses surged down the street. Steel was below its ductile/brittle transition temperature

The Silver Bridge Collapse

West Virginia December 1967. 46 deaths Stress-corrosion cracking resulting from long exposure to H2S vapour from nearby paper mill digesters.



API 579-1/ASME FFS-1 (2007)

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pt 57



What happened?

2007 in Pembroke, Wales.

Crack in the 30mm pipe allowing release of nitrogen into the inner space between the SS inner pressure vessel and the CS outer vessel.

This resulted in pressurisation of the external shell and brittle facture.



Assessment of Equipment for

Brittle Fracture

Possible reasons for assessment

Change in operating conditions

HAZOP identifies possibility of lower temperature

condition than considered in design

Equipment rerated using lower design margin

API 579-1/ASME FFS-1 (2007)

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pt 58



Brittle Fracture

Level 1

compliance with new construction code exemption curves

or impact test requirements

Level 2

include consideration of low stress-based temperature

reduction rules

exemption based on hydrotest

exemption based on service experience



Assessment Requirements

Summary of repairs and alterations

Past and future operating conditions

Current design pressure, temperature and current wall

thickness

API 579-1/ASME FFS-1 (2007)

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pt 59



Data

Determine CET loading-temperature envelope

Potential for autorefrigeration due to depressurization

Shock chilling effects



LEVEL 1 ASSESSMENT

Figure 3.4M Minimum Allowable Metal Temperature API 579/ASME FFS Page 3-29

API 579-1/ASME FFS-1 (2007)

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pt 60



CURVES

A TO D

Assignment Of Materials To The

Material Temperature Exemption

Curves In Figure 3.4

API 579/ASME FFS Page 3-19



EXERCISE

A horizontal drum 40mm wall thickness is fabricated from

ASTM A516 Gr.70 steel, supplied in the normalized condition.

There is no toughness data on this steel. The vessel was

designed and constructed to ASME B&PV Code Section VIII

Div.1.

Determine the MAT.

API 579-1/ASME FFS-1 (2007)

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pt 61



BRITTLE FRACTURE SHOP

HYDROTEST

Cr-Mo-V vessel

16.76m long x 1.575m x

142,5mm wall

Hydrotest P = 48,650kPa at

10oC ambient



EXERCISE

What is the hoop stress in the cylindrical shell of the

CR-Mo-V vessel during hydrotest at 48,650kPa?

If yield stress of the material is 275MPa, how do

you explain the failure?

Apply the following steps to this vessel:

Hydrotest temperature = 10oF

Material belongs to curve B.

API 579-1/ASME FFS-1 (2007)

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pt 62



CET - MAT

Critical Exposure Temperature (CET):

Lowest temperature at which component exposed to

Pressure vessels and piping: 30% MAWP

Tanks:

hydrotest temp.

daily min. operating temp. + 15oF (8oC)

Minimum Allowable Temperature (MAT):

Lowest metal temperature permitted in design code,

Based on resistance to brittle fracture.

CET > MAT

For MAT use construction code or Curves A to D.



Level 2 Assessment

Pressure Vessels

Method A (3.4.3.1) Safe operating envelope

MAT Temperature reduction rules

Method B (3.4.3.2) Hydrotest

Consider METAL temperature

Method C (3.4.3.3) Wall thickness

API 579-1/ASME FFS-1 (2007)

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pt 63



Level 2 Assessment

Piping Systems

Method A (3.4.3.4) Safe operating envelope

Use 3.4.3.1 if op stress < allowable stress

Method B (3.4.3.5) Hydrotest

Consider sustained/thermal loads

Method C (3.4.3.6) Figure 3.9 flowchart

Thickness < 38mm



Level 2 Assessment

Storage Tanks

Flowchart figure 3.3

API 620 tanks evaluated as pressure vessels

Levels 1&2 NOT used for atmospheric or LP with refrigerant

API 579-1/ASME FFS-1 (2007)

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pt 64



STORAGE TANK EXEMPTIONS

Figure 3.10M Exemption Curve for Tanks Constructed From Carbon Steel of Unknown Toughness Thicker Than 12.7 mm And Operating at A Shell Metal Temperature Below 16C

API 579/ASME FFS Page 3-42



Level 3

Detailed determination of 1 or more: stress,

flaw size

material toughness

Part 9 (crack) may be used as a basis for a Level 3 Assessment

Material Toughness

API 579-1/ASME FFS-1 (2007)

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pt 65



Brittle Fracture Wrap Up

Resistance evaluated only of carbon and low alloy

steel units.

Not for Boilers.

Not for ferritic, martensitic or duplex stainless steels

This Part is for screening NOT EVALUATION of an existing crack.

Use Part 9 for existing cracks.



Avoidance???

Use notch tough parent material, HAZ & weld metal or ductile stainless steel or non-ferrous metal. Avoid structural notches.

Good welding, WPQ, Qualified welder, NDE, QA, Inspection etc. Use low H2 electrodes, controlled heat input, fine grain low O2 weld metal

Keep applied stress low e.g. higher safety factor, accurate shape to reduce local bending/discontinuity stress.

Limit impact/shock loading.

Use slow heating and cooling or thermal sleeve to reduce thermal stress.

Avoid low temperature service or hydrotest condition. Reduce residual stress by PWHT.

API 579-1/ASME FFS-1 (2007)

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pt 66



API 579 PART 4

ASSESSMENT OF GENERAL METAL LOSS


132

GENERAL METAL LOSS

API 579-1/ASME FFS-1 (2007)

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pt 67



General Corrosion

Based on local thin area assessment rules

Point thickness readings may be used if metal loss

is confirmed to be general

COV

API 579-1/ASME FFS-1 (2007)

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pt 68



C.O.V.

Calculate the average thickness (minimum 15)

Calculate the difference between the actual thickness and the

average for EACH point

Calculate the square

Calculate the COV

135



Coefficient of Variation

Location Thickness reading

trd, i i=1 to N

(trd, i - tam) (trd, i - tam)2

1

2

3

4

5

We need t and tam (from table 4.2)

API 579-1/ASME FFS-1 (2007)

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Inspection Summary (table 4.2)



Use Point Thickness

138

API 579-1/ASME FFS-1 (2007)

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Level 1 (cont.)

Based on CTP L=Q(Dtmin)

If s< L, OK for meridional corrosion, check longitudinal corrosion using LTA Level 1 chart

If s>L, use point thickness readings with tam=tmm, or

determine average and minimum thickness for circumferential and meridional directions

determine tam over length L centered on tmm



General Corrosion - Level 2

Evaluation methods for shells the same as level 1, but

considers supplemental loads

Evaluation methods provided for components with thickness

interdependencies, such as nozzles, using average thickness

measurements over prescribed lengths

API 579-1/ASME FFS-1 (2007)

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pt 71



Level 1 using CTP Step 1 Determine tmm

Step 2 - Determine thickness profile data

Step 3 - Determine wall thickness for assessment

Step 4 - Compute remaining thickness ratio

Step 5 - Compute L for averaging length

Step 6 - Establish CTPs Determine tsam and t

cam

Step 7 - Determine acceptability using Table 4.4



EXERCISE

Pressure vessel

Design pressure/Temp. = 2068kPa

Inside diameter/wall thickness = 1292mm / 19mm

Corrosion allowance = 2.5mm

Material = SA 516 Grade 70

Weld joint efficiency = 0.85

API 579-1/ASME FFS-1 (2007)

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pt 72



EXERCISE

Results of ultrasonic readings show a corrosion zone along

the longitudinal weld.

The readings are 40mm apart in the circumferential and

longitudinal direction.

Can the vessel be kept in service, or should it be shutdown for

repair?



Data Evaluation

Level 1 Assessment Type A Components subject to internal pressure or

external pressure (i.e. supplemental loads are assumed to be negligible).

Level 2 Assessment Type A or B Components (see Part 4, paragraph 4.2.5)

subject to internal, v external pressure, supplemental loads (see Appendix A, paragraph A.2.6), or any combination thereof.

A Level 3 Assessment can be performed when the Level 1 and 2 Assessment procedures do not apply

API 579-1/ASME FFS-1 (2007)

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EXERCISE

C1 C2 C3 C4 C5 C6 C7 C8

M1 19 19 19 19 19 19 19 19

M2 19 12.2 13.2 14.48 14.22 14.73 15.25 19

M3 19 14.5 15 14 15 15.25 16.76 19

M4 19 15.5 11.9 14.73 9.15 14.73 16.25 19

M5 19 16 15 14.73 14.48 12.2 15.75 19

M6 19 14.48 15 15.49 14.48 14.25 12.45 19

M7 19 19 19 19 19 19 19 19



CORROSION

PROFILE

API 579-1/ASME FFS-1 (2007)

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API 579-1/ASME FFS-1 (2007)

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Coefficient of Variation Determine the COEFFICIENT OF VARIATION.

If the Coefficient Of Variation (COV) of the thickness readings is greater than 10%,

then use thickness profiles

total number of thickness readings, the number of thickness readings should

be greater than or equal to 15

The equation for the Coefficient of Variation is:

If using Critical Thickness Profile the minimum distance between the readings

is:

LS = grid spacing, mm

D = outer diameter, mm

tmin = minimum code required wall, mm

tnom = nominal wall thickness, mm

mmtDtL rdS 38}192;5.16129236.0min{}2;36.0min{ min



mmPSE

PRt 236.13

20686.085.0120658

)0025.0646.0(2068

6.0min

150

LEVEL 1 Analysis - STEP 1

STEP - 1. Determine the minimum required wall

thickness, and the future corrosion allowance FCA.

Appendix A paragraph A.2

FCA = 0.10

API 579-1/ASME FFS-1 (2007)

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pt 76



Level 1 STEP 2

STEP - 2. Measure thickness profile.

From the N measurement points ti, determine the minimum measured

thickness tmm

151

19

12.2 11.9

14

9.15

12.2 12.45

19

0

2

4

6

8

10

12

14

16

18

20

1 2 3 4 5 6 7 8

CTP

tmin

API 579-1/ASME FFS-1 FITNESS-FOR-SERVICE OF PIPING, VESSELS AND TANKS

asme api 579 si handouts

Documents

service of piping

asme codes

fitness of equipment

process api

api rules

strength api

foundations of fitness

tanks ron frend daily