1 INTRODUCTION....................................................................................3
1.1 SCC OVERVIEW....................................................................................................3
1.2 SCC IN PERSPECTIVE........................................................................................3
2 BACKGROUND.........................................................................................................5
2.1 PROBLEM STATEMENT ......................................................................................6
2.2 PROJECT SCOPE OVERVIEW ..........................................................................6
2.2.1 Phase 1................................................................................................................7
2.2.2 Phase 2................................................................................................................7
2.3 REPORT OUTLINE...............................................................................................7
3 LITERATURE REVIEW............................................................................................9
3.1 SCOPE STATEMENT ...........................................................................................9
3.2 LITERATURE SEARCH AND DATABASE..........................................................9
3.3 RECOMMENDED REFERENCES .....................................................................9
3.4 DATABASE DESCRIPTION ...............................................................................10
3.5 REFERENCES .................................................................................................13
4 UNDERSTANDING STRESS CORROSION CRACKING (SCC) IN PIPELINES....................................15
4.1 SCOPE STATEMENT ..................................................................................15
4.2 GENERAL CHARACTERIZATION (NEB 1996)...............................................15
4.2.1 High pH SCC (NEB 1996) ..............................................................................17
4.2.2 Near-neutral pH SCC (NEB 1996)................................................................18
4.2.3 Crack Characteristics ...................................................................................19
4.2.4 Crack Growth............................................................................................20
4.3 HISTORY OF SCC IN PIPELINES ..............................................................21
4.3.1 Canada/International (NEB 1996)...............................................................22
4.3.2 United States ...............................................................................................22
4.4 CONTRIBUTING FACTORS TO SCC IN PIPELINES...................................23
4.4.1 Metallurgy....................................................................................................23
4.4.2 Manufacturing...........................................................................23
4.4.3 Mechanical Properties ..............................................................24
4.4.4 Pipeline Operating Conditions..............................................................24
4.4.5 Coating...........................................................................................25
4.4.6 Soil conditions..........................................................................26
4.5 REFERENCES ...............................................................................................27
5 PREVENTION OF AN SCC PROBLEM ..............................................................29
5.1 SCOPE STATEMENT ..................................................................29
5.2 COATINGS...................................................................................29
5.3 PIPE STEEL SELECTION ...................................................................................31
5.4 DESIGN OPERATING PRESSURE ....................................................................32
5.5 DESIGN OPERATING TEMPERATURE.......................................................33
5.6 CONSTRUCTION..................................................................33
5.7 OPERATIONS AND MAINTENANCE............................................................34
5.7.1 Cathodic Protection ...........................................................34
5.7.2 Recoating Existing Pipelines....................................................34
5.7.3 Other Operational Considerations...........................................35
5.8 REFERENCES ........................................................................35
6 DETECTION OF SCC.....................................................................37
6.1 SCOPE STATEMENT ......................................................37
6.2 DETECTION METHODS ...........................................................................37
6.2.1 Hydrostatic Testing .........................................................................37
6.2.1.1 BENEFITS ...............................................................................................................................38
6.2.1.2 LIMITATIONS .........................................................................................................................38
6.2.2 In-Line Inspection (ILI)...................................................................................................................40
6.2.2.1 ILI TECHNOLOGIES................................................................................................................40
6.2.2.2 TOOL AVAILABILITY..............................................................................................................43
6.2.2.3 ILI CRACK CHARACTERIZATION............................................................................................44
6.2.2.4 ILI DEPLOYMENT ..................................................................................................................44
6.2.3 Direct Examination .........................................................................................................................45
6.2.3.1 VISUAL EXAMINATION ..........................................................................................................46
6.2.3.2 MAGNETIC PARTICLE.............................................................................................................46
6.2.3.3 LIQUID PENETRANT ...............................................................................................................46
6.2.3.4 EDDY CURRENT.....................................................................................................................47
6.2.3.5 ULTRASONIC SHEAR WAVE ...................................................................................................48
6.2.3.6 POTENTIAL DROP...................................................................................................................48
6.2.3.7 ALTERNATING CURRENT FIELD MEASUREMENT.............................48
6.2.4 Predictive Modeling.......................................................................................................................49
6.2.5 Comparison....................................................................................................................................49
6.3 DIRECT ASSESSMENT.........................................................49
6.3.1 Pre-Assessment Step .......................................................................................................................51
6.3.2 Indirect Inspection Step...................................................................................................................52
6.3.3 Direct Examination Step .................................................................................................................52
6.3.4 Post Assessment Step ......................................................................................................................52
6.4 REFERENCES ....................................................................................................53
7 MITIGATION OF SCC.................................................................................................55
7.1 REPAIR AND MITIGATION OPTIONS.............................................................................55
7.1.1 Pressure Reduction .........................................................................................................................55
7.1.2 Hydrostatic Testing and Repair ......................................................................................................55
7.1.2.1 SELECTIVE CRACK BLUNTING ...............................................................................................56
7.1.3 Recoating .......................................................................................................................................56
7.1.4 Extension of Exclusion Zones..........................................................................................................57
7.1.5 Grinding.........................................................................................................................................57
7.1.6 Pipe Sleeves ...................................................................................................................................57
7.1.7 Pipe Replacement...........................................................................................................................58
7.1.8 Options Discussion .........................................................................................................................58
7.2 REFERENCES .....................................................................................59
8 REGULATORY PRACTICES – UNITED STATES AND FOREIGN...............................61
8.1 SCOPE STATEMENT ......................................................................................61
8.2 US CODES AND STANDARDS EVALUATION....................................................61
8.2.1 49 CFR 192 and 195 ...............................................................................................61
8.2.2 ASME B31.4 ......................................................................................................61
8.2.3 ASME B31.8 and B31.8S.................................................................................................................61
8.2.4 ASME B31G and RSTRENG ...........................................................................................................62
8.2.5 API RP579......................................................................................................................................64
8.2.6 Other Failure Criteria Methods......................................................................................................65
8.2.6.1 NG-18 LN-SECANT FORMULA................................................................................................66
8.2.6.2 PIPE AXIAL FLAW FAILURE CRITERION .................................................................................67
8.2.6.3 LEVEL 2 STRIP YIELD MODEL ...............................................................................................67
8.2.6.4 CORLAS™.............................................................................................................................68
8.2.6.5 APPLICATION .........................................................................................................................71
8.2.6.6 COMPARISON .........................................................................................................................72
8.2.7 NACE International ........................................................................................................................73
8.2.7.1 PUBLICATION 35103 – EXTERNAL STRESS CORROSION CRACKING OF UNDERGROUND PIPELINES
73
8.2.7.2 RP – SCC DIRECT ASSESSMENT (DA) ..................................................................................74
8.2.8 Summary of US Codes and Standards...........................................................74
8.3 CANADIAN REGULATIONS AND STANDARDS..................................................75
8.3.1 National Energy Board ....................................................................75
8.3.2 CSA ...................................................................................................76
8.4 AUSTRALIAN REGULATIONS AND STANDARDS ..............................................77
8.4.1 AS 2885.1 Design and Construction .................................................77
8.4.2 AS 2885.3 Operations and Maintenance...........................................77
8.4.3 APIA.......................................................................................78
8.5 EUROPEAN REGULATIONS AND STANDARDS.....................................78
8.6 OTHER REGULATIONS, STANDARDS AND PRACTICES.......................................78
8.7 REFERENCES .......................................................................79
9 RESEARCH GAP ANALYSIS .....................................................................83
9.1 SCOPE STATEMENT .....................................................................83
9.2 SCC R&D NEEDS DISCUSSION.......................................................83
9.3 PRIORITIZATION OF R&D GAPS ...............................................................84
9.3.1 Criteria for Prioritizing...................................................................................................................84
9.3.2 Benefit Analysis..............................................................................................................................85
9.3.3 Cost Analysis..................................................................................................................................86
9.3.4 Summary of R&D Priorities............................................................................................................87
9.4 REFERENCES .................................................................................88
10 INDUSTRY PRACTICE REGARDING SCC....................................................89
10.1 SCOPE STATEMENT ......................................................................89
10.2 QUESTIONNAIRE CONCERNING CURRENT ASSESSMENT PROCEDURES................89
10.3 SUMMARY OF QUESTIONNAIRE RESPONSES ..........................................89
10.3.1 SCC Occurrence Information................................................................................89
10.3.2 SCC Detection Methods ..................................................................................................................90
10.3.3 SCC Management ...........................................................................................................................91
10.3.4 SCC Mitigation ...............................................................................................................................92
10.4 OPERATOR INTERVIEWS..............................................................93
10.4.1 Operator A .....................................................................................................................................94
10.4.2 Operator B .....................................................................................................................................95
10.4.3 Operator C .....................................................................................................................................97
10.4.4 Operator D.....................................................................................................................................99
10.4.5 Operator E ...................................................................................................................................101
10.4.6 Operator F ...................................................................................................................................103
10.4.7 Operator G...................................................................................................................................104
10.5 REFERENCES ......................................................................107
11 SCC IN INTEGRITY MANAGEMENT.............................................................109
11.1 SCOPE STATEMENT ................................................................................109
11.2 ASSESSMENT OF SCC RISK FACTOR IN INTEGRITY MANAGEMENT PLANS..............109
11.2.1 Natural Gas Pipelines – Protocol Review..................................109
11.2.2 Hazardous Liquids Pipelines – Protocol Review ......................................111
11.3 SPECIFIC PROTOCOL ISSUES TO BE ADDRESSED REGARDING SCC......................112
11.4 REFERENCES ...................................................................................115
12 RESPONSE TO SCC INCIDENTS ...................................................................117
12.1 SCOPE STATEMENT ................................................................................117
12.2 REGULATORY OVERSIGHT IN POST SCC INCIDENT RESPONSE........................117
12.3 INITIAL REPORT ........................................................................117
12.4 SITE SECURITY AND DATA COLLECTION..............................................118
12.5 PROCEDURAL DEVELOPMENT .....................................................................122
13 SUMMARY.............................................................125
13.1 CONCLUSIONS..........................................................................125
13.1.1 Design ..........................................................................................................................................125
13.1.2 Construction.................................................................................................................................125
13.1.3 Operations....................................................................................................................................126
13.1.4 SCC Awareness Program..............................................................................................................126
13.1.5 SCC Detection through ILI ...........................................................................................................126
13.1.6 SCC Detection through Direct Examination.......................................127
13.1.7 SCC Remediation ..........................................................................................................................127
13.1.8 IM Program – SCC .......................................................................................................................127
13.1.9 Response to In-Service Failure ................................................128
