Welding Inspection and Metallurgy

API RECOMMENDED PRACTICE 577 FIRST EDITION, OCTOBER 2004

Welding Inspection and Metallurgy

Downstream Segment

API RECOMMENDED PRACTICE 577 FIRST EDITION, OCTOBER 2004

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Copyright ©2004 American Petroleum Institute

FOREWORD

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 conflict.

Suggested revisions are invited and should be submitted to API, Standards department, 1220 L Street, NW, Washington, DC 20005, standards@api.org.

iii

1. Visual Examination (VT) 26

2. Magnetic Particle Examination (MT) 27

3. Alternating Current Field Measurement (ACFM) 36

4. Liquid Penetrant Examination (PT) 36

5. Eddy Current Inspection (ET) 37

6. Radiographic Inspection (RT) 37

7. Ultrasonic Inspection (UT) 49

8. Hardness Testing 54

9. Pressure and Leak Testing (LT) 54

10. Weld Inspection Data Recording 54

1. METALLURGY 55

   1. General 55

   2. The Structure of Metals and Alloys 55

   3. Physical Properties 58

   4. Mechanical Properties 59

   5. Preheating 61

   6. Post-weld Heat Treatment 61

   7. Hardening 62

   8. Material Test Reports 63

   9. Weldability of Steels 63

   10. Weldability of High-alloys 65

2. REFINERY AND PETROCHEMICAL PLANT WELDING ISSUES 66

   1. General 66

   2. Hot Tapping and In-service Welding 67

   3. Lack of Fusion with GMAW-S Welding Process 69

APPENDIX A TERMINOLOGY AND SYMBOLS 71

APPENDIX B ACTIONS TO ADDRESS IMPROPERLY MADE

PRODUCTION WELDS 77

APPENDIX C WELDING PROCEDURE REVIEW 79

APPENDIX D GUIDE TO COMMON FILLER METAL SELECTION. 95

APPENDIX E EXAMPLE REPORT OF RT RESULTS 99

Figures

1. SMAW Welding 10

2. SMAW Welding Electrode during Welding 10

3. GTAW Welding Equipment 12

4. GTAW Welding 12

5. GMAW Equipment 13

6. GMAW Welding 13

7. FCAW Equipment 15

8. FCAW Welding 15

9. FCAW Welding, Self-shielded 16

10. SAW Welding 16

11. Typical Discontinuities Present in a Single Bevel Groove Weld in a Butt Joint . . 23

12. Direct Visual Examination Requirements 26

13. Inspectors Kit 28

14. Bridge Cam Gauge 28

15. Adjustable Fillet Weld Gauge 29

16. Skew—T Fillet Weld Gauge 29

17. Weld Fillet Gauge 30

18. Weld Fillet Gauge 30

19. Weld Size Gauge 31

20. Hi-lo Gauge 31

21. Surface-breaking Discontinuity 32

22. Sub-surface Discontinuity 32

23. Weld Discontinuity 33

24. Flux Lines 33

25. Detecting Discontinuities Transverse to Weld 34

26. Detecting Discontinuities Parallel to the Weld 34

27. Pie Gauge 35

28. Florescent Penetrant Technique 36

29. IQI (Penetrameter) Common Hole Diameters 39

30. IQI (Penetrameter) 39

31. Single-wall Techniques 40

32. Double-wall Techniques 41

33. Incomplete or Lack of Penetration (LOP) 43

34. Interpass Slag Inclusions 43

35. Cluster Porosity 44

36. Lack of Side Wall Fusion 44

37. Elongated Slag (Wagon Tracks) 45

38. Burn-through 45

39. Offset or Mismatch with Lack of Penetration (LOP) 46

40. Excessive Penetration (Icicles, Drop-through) 46

41. Internal (Root) Undercut 47

42. Transverse Crack 47

43. Tungsten Inclusions 48

44. Root Pass Aligned Porosity 48

45. A-scan 50

46. B-scan 50

47. C-scan 51

48. DAC Curve for a Specified Reference Reflector 52

49. DAC Curve for an Unknown Reflector 52

1. Joint Types and Applicable Welds 72

2. Symbols for Various Weld Joint 73

3. Supplementary Symbols for Welds 73

4. Standard Weld Symbols 74

5. Groove Weld Nomenclature 74

6. SMAW Welding Electrode Identification System 75

7. GMAW/GTAW Welding Electrode Identification System 75

8. FCAW Welding Electrode Identification System 75

9. SAW Welding Electrode Identification System 76

1. Suggested Actions for Welds Made by an Incorrect Welder 77

2. Steps to Address Production Welds Made by an Improper Welding Procedure . . 78 C-1 Sample WPS #CS-1 80

1. Sample PQR #CS-1 82

2. Shielded Metal-Arc Welding (SMAW) Checklist 85

3. Example of Completed Shielded Metal-Arc Welding (SMAW) Checklist 88

Tables

1. P-number Assignments 19

2. Common Types of Discontinuities 22

3. Commonly Used NDE Methods 22

4. Capability of the Applicable Inspection Method for Weld Type Joints 23

5. Capability of the Applicable Inspection Method vs. Discontinuity 24

6. Discontinuities Commonly Encountered with Welding Processes 25

7. ASTM E 142 IQIs (Penetrameters) 38

8. Conditions that May Exist in a Material or Product 56

9. Results of Non-destructive Examination 56

10. Results of Application of Acceptance/Rejection Criteria 56

11. Brinell Hardness Limits for Steels in Refining Services 63

12. Weld Crack Tests 65

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

Particular Substances 68

D-1 Common Welding Consumables for SMAW of Carbon and Low-alloy Steel . . . 95 D-2 Common Welding Consumables for SMAW of Stainless Steels 96

1. Copper-nickel and Nickel-based Alloys 97

2. Classification Changes in Low-alloy Filler Metal Designations 98

Welding Inspection and Metallurgy

1. Scope

   This recommended practice provides guidance to the API authorized inspector on welding inspection as encountered with fabrication and repair of refinery and chemical plant equipment and piping. Common welding processes, welding procedures, welder qualifications, metallurgical effects from welding, and inspection techniques are described to aid the inspector in fulfilling their role implementing API 510, API 570, API Std 653 and API RP 582. The level of learning and training obtained from this document is not a replacement for the training and experience required to be an American Weld- ing Society (AWS) Certified Welding Inspector (CWI).

   This recommended practice does not require all welds to be inspected; nor does it require welds to be inspected to spe- cific 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 impor- tance, difficulty, and problems that could be encountered dur- ing welding should be considered by all involved. A welding engineer should be consulted on any critical, specialized or complex welding issues.

   
   

2. References

   1. CODES AND STANDARDS

      The following codes and standards are referenced in this recommended practice. All codes and standards are subject to periodic revision, and the most recent revision available should be used.

      
      

      API

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

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

      RP 578 Material Verification Program for New and Existing Alloy Piping Systems

      RP 582 Recommended Practice and Supplemen- tary Welding Guidelines for the Chemical, Oil, and Gas Industries

      Std 650 Welded Steel Tanks for Oil Storage

      Std 653 Tank Inspection, Repair, Alteration, and Reconstruction

      Publ 2201 Procedures for Welding or Hot Tapping on Equipment in Service

      1

      ASME1

      B31.3 Process Piping

      Boiler and Pressure Vessel Code Section V, Nondestructive Examination; Section VIII, Rules for Con- struction of Pressure Vessels, Section IX, Qualification Standard for Welding and Brazing Procedures, Welders, Brazers, and Welding and Brazing Operators

      Practical Guide to ASME Section IX—Welding Qualifications

      
      

      ASNT2

      ASNT Central Certification Program

      CP-189 Standard for Qualification and Certifica- tion of Nondestructive Testing Personnel

      SNT-TC-1A Personnel Qualification and Certification in Nondestructive Testing

      
      

      AWS3

      A2.4 Standard Symbols for Welding, Brazing, and Nondestructive Examination

      A3.0 Standard Welding Terms and Definitions

      A5.XX Series of Filler Metal Specifications

      B1.10 Guide for the Nondestructive Inspection of Welds

      CASTI4

      CASTI Guidebook to ASME Section IX—Welding Qualifications

      
      

      WRC5

      Bulletin 342 Stainless Steel Weld Metal: Prediction of Ferrite Content

      
      

   2. OTHER REFERENCES

The following codes and standards are not referenced directly in this recommended practice. Familiarity with these documents may be useful to the welding engineer or inspec- tor as they provide additional information pertaining to this recommended practice. All codes and standards are subject to

1ASME International, 345 East 47th Street, New York, New York 10017. www.asme.org

2American Society for Nondestructive Testing, Inc., 1711 Arlington Lane, P.O. Box 28518, Columbus, Ohio 43228-0518. www. asnt.org 3American Welding Society, 550 N.W. LeJeune Road, Miami, Flor- ida 33135. www.aws.org

4Codes and Standards Training Inc., Suite 210, 10544 106 Street, Edmonton AB T5H 2X6, Canada. www.casti.ca

5Welding Research Council, P.O. Box 1942, New York, New York 10056. www.forengineers.org/wrc/