Welding Processes, Inspection, and Metallurgy

API RECOMMENDED PRACTICE 577 SECOND EDITION, DECEMBER 2013

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Copyright © 2013 American Petroleum Institute

Foreword

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms, Definitions, and Acronyms 2

   1. Terms and Definitions 2

   2. Acronyms 10

4. Welding Inspection 10

   1. General 10

   2. Tasks Prior to Welding 10

   3. Tasks During Welding Operations 16

   4. Tasks Upon Completion of Welding 18

   5. Non-Conformances and Defects 21

   6. NDE Examiner Certification 21

   7. Safety Precautions 23

5. Welding Processes 23

   1. General 23

   2. Shielded Metal Arc Welding (SMAW) 23

   3. Gas Tungsten Arc Welding (GTAW). 25

   4. Gas Metal Arc Welding (GMAW) 27

   5. Flux Cored Arc Welding (FCAW) 30

   6. Submerged Arc Welding (SAW) 33

   7. Stud Arc Welding (SW) 33

   8. Plasma Arc Welding (PAW). 35

   9. Electrogas Welding (EGW) 36

6. Welding Procedure 38

   1. General 38

   2. Welding Procedure Specification (WPS) 38

   3. Procedure Qualification Record (PQR) 40

   4. Reviewing a WPS and PQR 40

   5. Tube-to-Tubesheet Welding Procedures 43

7. Welding Materials 44

   1. General 44

   2. P-Number Assignment to Base Metals 44

   3. F-Number Assignment to Filler Metals 44

   4. AWS Classification of Filler Metals 45

   5. A-Number 45

   6. Filler Metal Selection 45

   7. Consumable Storage and Handling 46

8. Welder Qualification 46

   1. General 46

   2. Welder Performance Qualification (WPQ) 46

   3. Reviewing a WPQ 47

9. Non-destructive Examination 48

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   Page

   1. Discontinuities 48

   2. Materials Identification 50

   3. Visual Examination (VT) 52

   4. Magnetic Particle Examination (MT) 57

   5. Alternating Current Field Measurement (ACFM) 64

   6. Liquid Penetrant Examination (PT) 64

   7. Eddy Current Examination (ET) 66

   8. Radiographic Examination (RT) 66

   9. Ultrasonic Examination (UT) 73

   10. Hardness Testing 90

   11. Pressure and Leak Testing (LT) 91

   12. Weld Inspection Data Recording 92

10. Metallurgy 94

    1. General 94

    2. The Structure of Metals and Alloys 95

    3. Physical Properties 97

    4. Mechanical Properties 99

    5. Preheating 101

    6. Postweld Heat Treatment 102

    7. Hardening 103

    8. Material Test Reports 104

    9. Weldability of Metals 105

    10. Weldability of high-alloys108

11. Refinery and Petrochemical Plant Welding Issues 109

    1. General 109

    2. Hot Tapping and In-Service Welding 109

    3. Lack of Fusion with GMAW-S Welding Process 112

    4. Caustic Service 113

Annex A (normative) Terminology and Symbols 114

Annex B (normative) Actions to Address Improperly Made Production Welds 120

Annex C (informative) Welding Procedure Review 122

Annex D (normative) Guide To Common Filler Metal Selection 140

Annex E (informative) Example Report of RT Results 144

Bibliography 145

Figures

1. SMAW Welding 24

2. SMAW Welding Electrode During Welding 24

3. GTAW Welding Equipment 26

4. GTAW Welding 27

5. GMAW Equipment 28

6. GMAW Welding 28

7. FCAW Equipment 31

8. FCAW Welding 32

9. FCAW Welding, Self-shielded 32

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   Page

10. SAW Welding 34

11. Comparison of the Gas Tungsten Arc and Plasma Arc Welding Processes 35

12. Electrogas Welding with a Solid Electrode 37

13. Typical Discontinuities Present in a Single Bevel Groove Weld in a Butt Joint 50

14. Direct Visual Examination Requirements 53

15. Inspector’s Kit 55

16. Bridge Cam Gauge 56

17. Adjustable Fillet Weld Gauge 56

18. Skew—T Fillet Weld Gauge 57

19. Weld Fillet Gauge 58

20. Weld Fillet Gauge 58

21. Weld Size Gauge 59

22. Hi-Lo Gauge 59

23. Surface-breaking Discontinuity 60

24. Subsurface Discontinuity 60

25. Weld Discontinuity 61

26. Flux Lines 62

27. Detecting Discontinuities Transverse to Weld 62

28. Detecting Discontinuities Parallel to the Weld 63

29. Pie Gauge 63

30. Fluorescent Penetrant Technique 65

31. IQI (Penetrameter) Common Hole Diameters 68

32. IQI (Penetrameter) 69

33. Single-wall Techniques 70

34. Double-wall Techniques 71

35. Incomplete or Lack of Penetration (LOP) 74

36. Interpass Slag Inclusions 74

37. Cluster Porosity. 75

38. Lack of Side Wall Fusion 75

39. Elongated Slag (Wagon Tracks) 76

40. Burn-through 76

41. Offset or Mismatch with Lack of Penetration (LOP) 77

42. Excessive Penetration (Icicles, Drop-through) 77

43. Internal (Root) Undercut 78

44. Transverse Crack 78

45. Tungsten Inclusions 79

46. Root Pass Aligned Porosity 79

47. A-scan 80

48. B-scan 80

49. C-scan 81

50. D-scan 82

51. S-scan 83

52. TOFD D-scan Display 84

53. TOFD B-scan 84

54. TOFD Transducer Arrangement and Ultrasonic Energy Beam Propagation 85

55. DAC Curve for a Specified Reference Reflector 87

56. DAC Curve for an Unknown Reflector 88

57. Location of Hardness Measurements 91

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Page

1. Joint Types and Applicable Welds 115

2. Symbols for Various Weld Joint 116

3. Supplementary Symbols for Welds 116

4. Standard Weld Symbols 117

5. Groove Weld Nomenclature 118

6. SMAW Welding Electrode Identification System 118

7. GMAW/GTAW/PAW Welding Electrode Identification System 118

8. FCAW Welding Electrode Identification System 119

9. SAW Welding Electrode Identification System 119

10. EGW Welding Electrode Identification System 119

1. Suggested Actions for Welds Made by an Incorrect Welder 120

2. Steps to Address Production Welds Made by an Improper Welding Procedure 121

C.1a Sample WPS #CS-1, Page 1 of 2 124

C.1b Sample WPS #CS-1, Page 2 of 2 125

C.2a Sample PQR #CS-1, Page 1 of 2 126

C.2b Sample PQR #CS-1, Page 2 of 2 127

C.3a Shielded Metal-Arc Welding (SMAW) Checklist, Page 1 of 2 128

C.3b Shielded Metal-Arc Welding (SMAW) Checklist, Page 2 of 2 129

C.4a Example of Completed Shielded Metal-Arc Welding (SMAW) Checklist, Page 1 of 2 131

C.4b Example of Completed Shielded Metal-Arc Welding (SMAW) Checklist, Page 2 of 2 132

Tables

1. P-Number Assignments 45

2. Common Types of Discontinuities 49

3. Commonly Used NDE Methods 50

4. Capability of the Applicable Inspection Method for Weld Type Joints 51

5. Capability of the Applicable Inspection Method vs. Discontinuity 51

6. Discontinuities Commonly Encountered with Welding Processes 52

7. ASTM E94 IQIs (Penetrameters) 68

8. Conditions that May Exist in a Material or Product 94

9. Results of Non-destructive Examination 94

10. Results of Application of Acceptance/Rejection Criteria 94

11. Brinell Hardness Limits for Steels in Refining Services 104

12. Weld Crack Tests 107

13. Hot Tapping/In-service Welding Hazards Associated with Some Particular Substances 111

1. Common Welding Consumables for SMAW of Carbon and Low-allow Steel 140

2. Common Welding Consumables for SMAW of Carbon and Low-allow Steel 141

3. Copper-nickel and Nickel-based Alloys 142

4. Classification Changes in Low-alloy Filler Metal Designations 143

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Welding Processes, Inspection, and Metallurgy

1. Scope

   
   

   This recommended practice (RP) provides guidance to the API authorized inspector on welding inspection as encountered with fabrication and repair of refinery and chemical plant equipment and piping. This RP includes descriptions of common welding processes, welding procedures, welder qualifications, metallurgical effects from welding, and inspection techniques to aid the inspector in fulfilling their role implementing API 510, API 570, API 653 and API 582. The level of learning and training obtained from this document is not a replacement for the training and experience required to be a certified welding inspector under one of the established welding certification programs such as the American Welding Society (AWS) Certified Welding Inspector (CWI), or Canadian and European equivalent schemes such as CWB, CSWIP, PCN, or EFW.

   
   

   This RP does not require all welds to be inspected; nor does it require welds to be inspected to specific techniques and extent. Welds selected for inspection, and the appropriate inspection techniques, should be determined by the welding inspectors, engineers, or other responsible personnel using the applicable code or standard. The importance, difficulty, and problems that could be encountered during welding should be considered by all involved. A welding engineer should be consulted on any critical, specialized or complex welding issues.

   
   

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 510, Pressure Vessel Inspection Code: Maintenance, Inspection, Rating, Repair, and Alteration

API 570, Piping Inspection Code: Inspection, Repair, Alteration, and Rerating of In-Service Piping Systems

API Recommended Practice 574, Inspection Practices for Piping System Components

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

API Recommended Practice 582, Recommended Practice and Supplementary Welding Guidelines for the Chemical, Oil, and Gas Industries

API Standard 650, Welded Steel Tanks for Oil Storage

API Standard 653, Tank Inspection, Repair, Alteration, and Reconstruction

API Recommended Practice 2201, Procedures for Welding or Hot Tapping on Equipment in Service

ASME Boiler and Pressure Vessel Code 1

B31.3, Process Piping

Section VIII, Rules for Construction of Pressure Vessels

Section IX, Qualification Standard for Welding and Brazing Procedures, Welders, Brazers, and Welding and Brazing Operators

Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components

Practical Guide to ASME Section IX, Welding Qualifications

1 ASME International, 3 Park Avenue, New York, New York 10016-5990, www.asme.org.

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