RECOMMENDED PRACTICE 572 SECOND EDITION, FEBRUARY 2001

Downstream Segment

RECOMMENDED PRACTICE 572 SECOND EDITION, FEBRUARY 2001

API publications necessarily address problems of a general nature. With respect to partic- ular circumstances, local, state, and federal laws and regulations should be reviewed.

API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations under local, state, or fed- eral laws.

Information concerning safety and health risks and proper precautions with respect to par- ticular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety data sheet.

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Generally, API standards are reviewed and revised, reaf?rmed, or withdrawn at least every

?ve years. Sometimes a one-time extension of up to two years will be added to this review cycle. This publication will no longer be in effect ?ve years after its publication date as an operative API standard or, where an extension has been granted, upon republication. Status of the publication can be ascertained from the API Downstream Segment [telephone (202) 682-8000]. A catalog of API publications and materials is published annually and updated quarterly by API, 1220 L Street, N.W., Washington, D.C. 20005.

This document was produced under API standardization procedures that ensure appropri- ate noti?cation and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this standard or com- ments and questions concerning the procedures under which this standard was developed should be directed in writing to the standardization manager, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the gen- eral manager.

API standards are published to facilitate the broad availability of proven, sound engineer- ing and operating practices. These standards are not intended to obviate the need for apply- ing sound engineering judgment regarding when and where these standards should be utilized. The formulation and publication of API standards is not intended in any way to inhibit anyone from using any other practices.

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Copyright ? 2001 American Petroleum Institute

FOREWORD

This recommended practice covers the inspection of pressure vessels. It is based on the accumulated knowledge and experience of engineers and other personnel in the petroleum industry.

The information contained in this publication was previously presented as Chapter VI and Chapter VII of the Guide for Inspection of Re?nery Equipment. The information in this rec- ommended practice does not constitute and should not be construed as a code of rules, regu- lations, or minimum safe practices. The practices described in this publication are not intended to supplant other practices that have proven satisfactory, nor is this publication intended to discourage innovation and originality in the inspection of re?neries. Users of this recommended practice are reminded that no book or manual is a substitute for the judgment of a responsible, quali?ed person.

API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may con?ict.

Suggested revisions are invited and should be submitted to the standardization manager, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.

iii

IMPORTANT INFORMATION CONCERNING USE OF ASBESTOS OR ALTERNATIVE MATERIALS

Asbestos is speci?ed or referenced for certain components of the equipment described in some API standards. It has been of extreme usefulness in minimizing ?re hazards associated with petroleum processing. It has also been a universal sealing material, compatible with most re?ning ?uid services.

Certain serious adverse health effects are associated with asbestos, among them the serious and often fatal diseases of lung cancer, asbestosis, and mesothelioma (a cancer of the chest and abdominal linings). The degree of exposure to asbestos varies with the prod- uct and the work practices involved.

Consult the most recent edition of the Occupational Safety and Health Administration (OSHA), U.S. Department of Labor, Occupational Safety and Health Standard for Asbestos, Tremolite, Anthophyllite, and Actinolite, 29 Code of Federal Regulations Section 1910.1001; the U.S. Environmental Protection Agency, National Emission Standard for Asbestos, 40 Code of Federal Regulations Sections 61.140 through 61.156; and the U.S. Environmental Protection Agency (EPA) rule on labeling requirements and phased banning of asbestos products (Sections 763.160-179).

There are currently in use and under development a number of substitute materials to replace asbestos in certain applications. Manufacturers and users are encouraged to develop and use effective substitute materials that can meet the speci?cations for, and operating requirements of, the equipment to which they would apply.

SAFETY AND HEALTH INFORMATION WITH RESPECT TO PARTICULAR PRODUCTS OR MATERIALS CAN BE OBTAINED FROM THE EMPLOYER, THE MANUFACTURER OR SUPPLIER OF THAT PRODUCT OR MATERIAL, OR THE MATERIAL SAFETY DATA SHEET.

1. SCOPE 1

2. REFERENCES 1

3. DEFINITIONS 1

4. TYPES OF PRESSURE VESSELS 2

   1. Description 2

   2. Methods of Construction 2

   3. Materials of Construction 2

   4. Internal Equipment 4

   5. Uses of Pressure Vessels 4

5. CONSTRUCTION STANDARDS 4

6. MAINTENANCE INSPECTION 6

7. REASONS FOR INSPECTION 8

   1. General 8

   2. Safety 8

   3. Continuity 8

   4. Reliability 8

8. CAUSES OF DETERIORATION 8

   1. General 8

   2. Corrosion Mechanisms 8

   3. Metallurgical and Physical Changes 14

   4. Faulty Material 16

   5. Faulty Fabrication 16

9. FREQUENCY AND TIME OF INSPECTION 17

   1. Factors Governing Frequency of Inspection 17

   2. Opportunities for Inspection 17

   3. Inspection Schedule 18

   4. Alternative Rules for Exploration and Production Vessels 18

10. INSPECTION METHODS AND LIMITATIONS 18

    1. General 18

    2. Safety Precautions and Preparatory Work 19

    3. External Inspection 20

    4. Internal Inspection 26

    5. Thickness-measuring Methods 33

    6. Special Methods Of Detecting Mechanical Defects 34

    7. Metallurgical Changes And In-situ Analysis Of Metals 34

    8. Testing 34

    9. Limits of Thickness 36

11. METHODS OF REPAIR 37

    CONTENTS

    Page

12. RECORDS AND REPORTS 38

    1. Records 38

    2. Reports 38

APPENDIX A?EXCHANGERS 39

APPENDIX B?SAMPLE RECORD FORMS 53

Figures

1?Type 316 Stainless-Clad Vessel 3

2?Weld Metal Surfacing 3

3?Strip-Lined Vessel 3

4?Principal Strip-Lining Methods 4

5?Reinforced Refractory Lining for Regenerator Lines and Slide Valves 4

6?Catalyst Storage Hoppers 5

7?Horizontal Drums 5

8?Spheres 6

9?Horton Spheroid (Noded) 6

10?Process Towers and Drums 7

11?Fluid Catalytic Regenerator 8

12?Caustic-Stress Corrosion 9

13?Severe Graphitic Corrosion of Floating-Head Cover 9

14?Plug-Type Dezinci?cation 9

15?Layer-Type Dezinci?cation 9

16?Tube Sheet Fouled With Marine Growth 10

17?Tube Sheet Corroded Beneath Marine Growth 10

18?Internal Vessel Corrosion 11

19?Erosion 11

20?Condensate Grooving of Tube in Area Adjoining Tube Sheet 11

21?Intergranular Corrosion 14

22?Thermal and Pressure Damage 14

23?Fatigue Cracking at Nozzle 14

24?Exchanger Installation and Foundation 21

25?Severe Deterioration of Anchor Bolts 22

26?Method of Obtaining Vessel Pro?le Measurements 25

27?Pitting in Channel 27

28?Crack in Shell Weld 28

29?Catalytic-Reactor Internals?Cyclones 29

30?Hydrogen Blistering 29

31?Cross Section Through Hydrogen Blisters Showing Various Types of

Crack Propagation 30

32?Corrosion Tab Method of Determining Metal Loss on Vessel Linings 31

33?Strip-Liner Deterioration 32

34?Deteriorated Refractory-Tile Lining 32

35?Steps in Using Special Equipment to Test Individual Tubes 36

A-1?Properly Rolled Tube 39

A-2?Tube-Bundle Type of Tank Heater 41

A-3?Air-Cooled Exchangers 41

A-4?Clean-Service Double-Pipe Coils 42

vi

A-5?Tank Suction Heater With Everything But Forward End

Enclosed; Shell Suction Nozzle Enclosed in Far End 43

A-6?Fin-Type Tubes in Double-Pipe Coil 44

A-7?Plate-Type Exchanger 44

A-8?Tubes Thinned at Baf?es 45

A-9?Erosion-Corrosion Attack at Tube Ends 46

A-10?Heat Exchanger Parts 48

A-11?Heat Exchanger Types 52

Inspection of Pressure Vessels

(Towers, Drums, Reactors, Heat Exchangers, and Condensers)

1. Scope

   This Recommended Practice (RP) covers the inspection of pressure vessels. It includes a description of the various types of pressure vessels and the standards for their construction and maintenance. The reasons for inspection, causes of dete- rioration, frequency and methods of inspection, methods of repair, and preparation of records and reports are covered. Safe operation is emphasized.

   
   

2. References

   The latest editions of the following standards, codes, and recommended practices shall, to the extent speci?ed herein, form a part of this recommended practice.

   API

   IRE, Guide for Inspection of Re?nery Equip-

   Chapter II ment, Conditions Causing Deterioration or Failures (out of print; to be replaced by RP 571, currently under development)

   Std 510 Pressure Vessel Inspection Code: Mainte- nance Inspection, Rating, Repair, and Alteration

   RP 574 Inspection Practices for Piping System Components

   RP 575 Inspection of Atmospheric and Low-Pres- sure Storage Tanks

   RP 576 Inspection of Pressure-Relieving Devices

   RP 579 Fitness-for-Service

   Std 660 Shell-and-Tube Heat Exchangers for Gen- eral Re?nery Service

   Std 661 Air-Cooled Heat Exchangers for General Re?nery Services

   Publ 938 An Experimental Study of Causes and Repair of Cracking of 11?4 Cr-1?2 Mo Steel Equipment

   Publ 939 Research Reporting on Characterization and Monitoring of Cracking in Wet H2S Service

   RP 941 Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Re?neries and Petroleum Plants

   RP 945 Avoiding Environmental Cracking of Car- bon Steels in Amine Units

   Publ 2214 Spark Ignition Properties of Hand Tools

   Publ 2217A Guidelines for Work in Inert Con?ned Spaces in the Petroleum Industry

   ASME1

   Boiler and Pressure Vessel Code, Section VIII, ?Pressure Vessels?

   1

   
   

   NB2

   NB-23 National Board Inspection Code

   TEMA3

   Standards of Tubular Exchanger Manufac- turers Association

   WRC4

   Bulletin 411 An Experimental Study of Causes and Repair of Cracking of 11?4 Cr-1?2 Mo Steel Equipment

   
   

3. Definitions

   For the purposes of this publication, the following de?ni- tions apply:

   1. CUI: Corrosion under insulation, which includes stress corrosion cracking under insulation.

   2. defect: In NDE usage, a defect is an imperfection of a type or magnitude exceeding the acceptable criteria.

   3. inspector: An authorized pressure vessel inspector.

   4. jurisdiction: A legally constituted government admin- istration that may adopt rules relating to pressure vessels.

   5. on-stream: Pressure vessels containing any amount of process ?uid.

   6. PT: Liquid penetrant testing.

   7. pressure vessel: A container that falls within the scope of Section VIII of the ASME Boiler & Pressure Vessel Code and is subject to an external or internal design pressure greater than 15 lbf/in.2 (103 kPa).

   8. pressure vessel engineer: One or more persons or organizations acceptable to the owner-user who are knowl- edgeable and experienced in the engineering disciplines asso- ciated with evaluating mechanical and material characteristics that affect the integrity and reliability of pres- sure vessels. The pressure vessel engineer, by consulting with appropriate specialists, should be regarded as a composite of all entities necessary to properly address a technical require- ment.

1ASME International, Three Park Avenue, New York, New York 10016-5990, www.asme.org.

2National Board of Boiler and Pressure Vessel Inspectors, 1055 Crupper Ave, Columbus, Ohio 43229, www.nationalboard.com.

3Tubular Exchanger Manufacturers Association, 25 North Broad- way, Tarrytown, New York 10591, www.tema.org.

4Welding Research Council, ThreePark Avenue, 27th Floor, New York, New York 10016, www.forengineers.org.