Inspection Practices for Piping System Components

API RECOMMENDED PRACTICE 574 FOURTH EDITION, NOVEMBER 2016

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Copyright © 2016 American Petroleum Institute

Foreword

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1. Scope 1

2. Normative References 1

3. Terms, Definitions, Acronyms, and Abbreviations 2

   1. Terms and Definitions 2

   2. Acronyms and Abbreviations 11

4. Piping Components 12

   1. Piping 12

   2. Tubing 23

   3. Valves 23

   4. Fittings 28

   5. Flanges 31

   6. Expansion Joints 31

   7. Piping Supports 31

   8. Flexible Hoses 33

5. Pipe-joining Methods 33

   1. General 33

   2. Threaded Joints 33

   3. Welded Joints 33

   4. Flanged Joints 34

   5. Cast Iron Pipe Joints 34

   6. Tubing Joints 34

   7. Special Joints 34

   8. Nonmetallic Piping Joints 37

6. Reasons for Inspection 38

   1. General 38

   2. Process and Personnel Safety 38

   3. Reliable Operation 38

   4. Regulatory Requirements 39

7. Inspection Plans 39

   1. General 39

   2. Developing an Inspection Plan 39

   3. Monitoring Process Piping 41

   4. Inspection for Specific Damage Mechanisms 47

   5. Integrity Operating Windows 63

8. Frequency and Extent of Inspection 64

   1. General 64

   2. On-stream Inspection 64

   3. Offline Inspection 65

   4. Inspection Scope 65

9. Safety Precautions and Preparatory Work 65

   1. Safety Precautions 65

   2. Communication 66

   3. Preparatory Work 66

   4. Investigation of Leaks 68

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10. Inspection Procedures and Practices 68

    1. External Visual Inspection 68

    2. Thickness Measurements 73

    3. Internal Visual Inspection 80

    4. Nonmetallic Piping 85

    5. Flexible Hoses 87

11. Pressure Tests 88

    1. Purpose of Testing 88

    2. Performing Pressure Tests 88

    3. Hammer Testing 90

    4. Tell-tale Hole Drilling 90

    5. Inspection of Piping Welds 91

    6. Other Inspection Methods 91

    7. Inspection of Underground Piping 91

    8. Inspection of New Fabrication, Repairs, and Alterations 100

12. Determination of Minimum Required Thickness 102

    1. Piping 102

    2. Valves and Flanged Fittings 105

13. Records 106

    1. General 106

    2. Sketches 106

    3. Numbering Systems 108

    4. Thickness Data 108

    5. Review of Records 108

    6. Record Updates 108

    7. Audit of Records 108

Annex A (informative) External Inspection Checklist for Process Piping 110

Bibliography 111

Figures

1. Cross Section of a Typical Wedge Gate Valve 24

2. Cross Section of a Typical Globe Valve 25

3. Cross Sections of Typical Lubricated and Nonlubricated Plug Valves 26

4. Cross Section of a Typical Ball Valve 26

5. Cross Section of a Typical Diaphragm Valve 27

6. Typical Butterfly Valve 27

7. Cross Sections of Typical Check Valves 28

8. Cross Section of a Typical Slide Valve 29

9. Flanged-end Fittings and Wrought Steel Butt-welded Fittings 30

10. Forged Steel Threaded and Socket-welded Fittings 30

11. Cross Section of a Socket-welded Tee Connection 35

12. Flange Facings Commonly Used in Refinery and Chemical Plant Piping 35

13. Types of Flanges 36

14. Cross Section of a Typical Bell-and-spigot Joint 36

15. Cross Sections of Typical Packed and Sleeve Joints 36

16. Cross Sections of Typical Tubing Joints 37

17. Piping Circuit Example 48

    
    

18. Erosion of Piping 49

19. Corrosion of Piping 49

20. Internal Corrosion of Piping 50

21. Severe Atmospheric Corrosion of Piping 50

22. SAI Corrosion 57

23. Case of Doubling due to Mode Converted Shear Wave Echo Occurring Between the Backwall Echoes 75

24. Example of Screen Display of UT Thickness Gauge with Automatic Temperature Compensation 78

25. Radiograph of a Catalytic Reformer Line 80

26. Radiograph of Corroded Pipe Whose Internal Surface is Coated with Iron Sulfide Scale 80

27. Sketch and Radiograph of Dead-end Corrosion 80

28. Underground Piping Corrosion Beneath Poorly Applied Tape Wrap 92

29. Pipe-to-soil Internal Potential Survey Use to Identify Active Corrosion Spots in Underground Piping . 93 30 Example of Pipe-to-Soil Potential Survey Chart 94

1. Wenner Four-pin Soil Resistivity Test 96

2. Soil Bar Used for Soil Resistivity Measurements 97

3. Two Types of Soil Boxes Used for Soil Resistivity Measurements 98

4. Typical Isometric Sketch 107

5. Typical Tabulation of Thickness Data 109

Tables

1. Nominal Pipe Sizes, Schedules, Weight Classes, and Dimensions of Ferritic Steel Pipe 14

2. Nominal Pipe Sizes, Schedules, and Dimensions of Stainless Steel Pipe 18

3. Permissible Tolerances in Diameter and Thickness for Ferritic Pipe 20

4. Mix Point Thermal Fatigue Screening Criteria 53

5. Damage Mechanisms Associated with Nonmetallic Piping 62

6. Comparison of Common Nonmetallic Piping NDE Techniques 86

7. Minimum Thicknesses for Carbon and Low-alloy Steel Pipe 105

Inspection Practices for Piping System Components

1. Scope

   
   

   This recommended practice (RP) supplements API 570 by providing piping inspectors with information that can improve skill and increase basic knowledge of inspection practices. This RP describes inspection practices for piping, tubing, valves (other than control valves), and fittings used in petroleum refineries and chemical plants. Common piping components, valve types, pipe joining methods, inspection planning processes, inspection intervals and techniques, and types of records are described to aid the inspectors in fulfilling their role implementing API 570. This publication does not cover inspection of specialty items, including instrumentation, furnace tubulars, and control valves.

   
   

2. Normative References

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

API 570, Piping Inspection Code: Inspection, Repair, Alteration, and Rerating of In-service Piping Systems API Recommended Practice 571, Damage Mechanisms Affecting Fixed Equipment in the Refining Industry API Recommended Practice 577, Welding Inspection and Metallurgy

API Recommended Practice 578, Material Verification Program for New and Existing Alloy Piping Systems

API 579-1/ASME FFS-1 1, Fitness-For-Service

API Recommended Practice 580, Risk-Based Inspection

API Recommended Practice 583, Corrosion Under Insulation and Fireproofing

API Recommended Practice 584, Integrity Operating Windows

API Standard 598, Valve Inspection and Testing

API Recommended Practice 932-B, Design, Materials, Fabrication, Operation, and Inspection Guidelines for Corrosion Control in Hydroprocessing Reactor Effluent Air Cooler (REAC) Systems

API Recommended Practice 941, Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants

ASME B16.5, Pipe Flanges and Flanged Fittings: NPS 1/2 Through NPS 24 Metric/Inch Standard ASME B16.20, Metallic Gaskets for Pipe Flanges: Ring-Joint, Spiral-Wound, and Jacketed ASME B16.25, Buttwelding Ends

ASME B16.34, Valves: Flanged, Threaded, and Welding End

ASME B16.47, Large Diameter Steel Flanges: NPS 26 Through NPS 60 Metric/Inch Standard

ASME B31.3, Process Piping

ASME Boiler and Pressure Vessel Code (BPVC), Section V: Nondestructive Examination

ASME Boiler and Pressure Vessel Code (BPVC), Section V: Nondestructive Examination; Article 11: Acoustic Emission Examination of Fiber Reinforced Plastic Vessels

ASME PCC-1, Guidelines for Pressure Boundary Bolted Flange Joint Assembly

ASME PCC-2, Repair of Pressure Equipment and Piping

1 ASME International, 2 Park Avenue, New York, New York 10016-5990, www.asme.org.

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