ASME B31.8-2012
(Revision of ASME B31.8-2010)
Gas Transmission and
Distribution Piping
Systems
ASME Code for Pressure Piping, B31
A N A M E R I C A N N AT I O N A L STA N DA R D
ASME B31.8-2012
(Revision of ASME B31.8-2010)
Gas Transmission and
Distribution Piping
Systems
ASME Code for Pressure Piping, B31
A N A M E R I C A N N AT I O N A L S TA N D A R D
Three Park Avenue • New York, NY • 10016 USA
Date of Issuance: January 4, 2013
The next edition of this Code is scheduled for publication in 2014. This Code will become effective
6 months after the Date of Issuance.
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The American Society of Mechanical Engineers
Three Park Avenue, New York, NY 10016-5990
Copyright © 2013 by
THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS
All rights reserved
Printed in U.S.A.
CONTENTS
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Committee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Summary of Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
viii
x
xiv
xvi
806
807
General Provisions and Definitions
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope and Intent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Piping Systems Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Piping Systems Component Definitions . . . . . . . . . . . . . . . . . .
Design, Fabrication, Operation, and Testing Terms and
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Quality Assurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Training and Qualification of Personnel . . . . . . . . . . . . . . . . . .
6
12
12
Chapter I
810
811
812
813
814
815
816
817
Materials and Equipment
Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Qualification of Materials and Equipment . . . . . . . . . . . . . . .
Materials for Use in Low Temperature Applications . . . . . .
Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Material Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Equipment Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transportation of Line Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conditions for the Reuse of Pipe . . . . . . . . . . . . . . . . . . . . . . . .
14
14
15
15
15
16
16
16
Table
817.1.3-1
Tensile Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
801
802
803
804
805
Chapter II
820
821
822
823
824
825
826
827
Chapter III
830
831
832
833
834
835
Tables
831.4.2-1
832.2-1
Welding
Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparation for Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Qualification of Procedures and Welders . . . . . . . . . . . . . . . . .
Preheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stress Relieving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Weld Inspection Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair or Removal of Defective Welds in Piping Intended
to Operate at Hoop Stress Levels of 20% or More of
the Specified Minimum Yield Strength . . . . . . . . . . . . . . . .
Piping System Components and Fabrication Details
Piping System Components and Fabrication Details . . . . . .
Piping System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Expansion and Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Design for Longitudinal Stress . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supports and Anchorage for Exposed Piping . . . . . . . . . . . .
Anchorage for Buried Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reinforcement of Welded Branch Connections, Special
Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermal Expansion or Contraction of Piping
Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iii
1
1
2
4
19
19
19
19
20
20
21
22
23
23
29
30
33
33
28
30
832.5-1
Chapter IV
840
841
842
843
844
845
846
847
848
849
Tables
841.1.6-1
841.1.6-2
841.1.7-1
841.1.8-1
841.1.11-1
841.2.3-1
841.3.2-1
841.3.3-1
842.1.1-1
842.2.2-1
842.2.3-1
842.2.9-1
844.3-1
844.3-2
845.2.2-1
845.2.3-1
845.2.3-2
Chapter V
850
851
852
853
854
855
856
857
Modulus of Elasticity for Carbon and Low Alloy
Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31
Design, Installation, and Testing
Design, Installation, and Testing . . . . . . . . . . . . . . . . . . . . . . . . .
Steel Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipe-Type and Bottle-Type Holders . . . . . . . . . . . . . . . . . . . . . .
Control and Limiting of Gas Pressure . . . . . . . . . . . . . . . . . . . .
Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Customers’ Meters and Regulators . . . . . . . . . . . . . . . . . . . . . .
Gas Service Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
37
50
58
61
62
67
68
69
70
Basic Design Factor, F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Design Factors for Steel Pipe Construction . . . . . . . . . . . . . . .
Longitudinal Joint Factor, E . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Derating Factor, T, for Steel Pipe . . . . . . . . . . .
Pipeline Cover Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipeline Field Cold Bend Requirements . . . . . . . . . . . . . . . . . .
Test Requirements for Steel Pipelines and Mains to
Operate at Hoop Stresses of 30% or More of the
Specified Minimum Yield Strength of the Pipe . . . . . . . . .
Maximum Hoop Stress Permissible During an Air or Gas
Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standard Thickness Selection Table for Ductile
Iron Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wall Thickness and Standard Dimension Ratio for
Thermoplastic Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diameter and Wall Thickness for Reinforced
Thermosetting Plastic Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nominal Values for Coefficients of Thermal Expansion
of Thermoplastic Pipe Materials . . . . . . . . . . . . . . . . . . . . . . .
Design Factors, F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Minimum Clearance Between Containers and Fenced
Boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Allowable Operating Pressure for Steel or
Plastic Pipelines or Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Allowable Operating Pressure for Pipelines
Operating at 100 psig (690 kPa) or More . . . . . . . . . . . . . . .
Maximum Allowable Operating Pressure for Pipelines
Operating at Less Than 100 psig (690 kPa) . . . . . . . . . . . .
Operating and Maintenance Procedures
Operating and Maintenance Procedures Affecting the
Safety of Gas Transmission and Distribution
Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipeline Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Distribution Piping Maintenance . . . . . . . . . . . . . . . . . . . . . . . .
Miscellaneous Facilities Maintenance . . . . . . . . . . . . . . . . . . . .
Location Class and Changes in Number of Buildings
Intended for Human Occupancy . . . . . . . . . . . . . . . . . . . . . .
Pipeline Service Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Odorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Uprating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iv
40
40
41
41
43
44
48
49
51
53
53
55
61
61
62
63
63
74
76
82
85
88
89
90
91
Figure
851.4.1-1
Table
851.4.4-1
854.1-1
857.4-1
Chapter VI
860
861
862
863
864
865
866
867
868
Allowable Ripple Heights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wall Thickness for Unlikely Occurrence of BurnThrough . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Location Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wall Thickness Allowance for Uprating a Ductile Iron
High-Pressure Main or System . . . . . . . . . . . . . . . . . . . . . . . .
Corrosion Control
Corrosion Control — General . . . . . . . . . . . . . . . . . . . . . . . . . . . .
External Corrosion Control for Steel Pipelines . . . . . . . . . . . .
Cathodic Protection Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operation and Maintenance of Cathodic Protection
Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internal Corrosion Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Steel Pipelines in Arctic Environments . . . . . . . . . . . . . . . . . . .
Steel Pipelines in High-Temperature Service . . . . . . . . . . . . .
Stress Corrosion and Other Phenomena . . . . . . . . . . . . . . . . . .
Cast Iron, Wrought Iron, Ductile Iron, and Other Metallic
Pipelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter VII
Intentionally Left Blank
Chapter VIII
A800
A801
A802
A803
A811
A814
A817
A820
A821
A823
A825
A826
A830
A831
A832
A834
A835
A840
A841
A842
A843
A844
A846
A847
A850
Offshore Gas Transmission
Offshore Gas Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope and Intent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Offshore Gas Transmission Terms and Definitions . . . . . . . .
Qualification of Materials and Equipment . . . . . . . . . . . . . . .
Material Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conditions for the Reuse and Requalification of Pipe . . . .
Welding Offshore Pipelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Qualification of Procedures and Welders . . . . . . . . . . . . . . . . .
Stress Relieving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection of Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Piping System Components and Fabrication Details . . . . . .
Piping System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Expansion and Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supports and Anchorage for Exposed Piping . . . . . . . . . . . .
Anchorage for Buried Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Design, Installation, and Testing . . . . . . . . . . . . . . . . . . . . . . . . .
Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Strength Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On-Bottom Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating and Maintenance Procedures Affecting the
Safety of Gas Transmission Facilities . . . . . . . . . . . . . . . . . .
Pipeline Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Location Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Corrosion Control of Offshore Pipelines . . . . . . . . . . . . . . . . . .
External Corrosion Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cathodic Protection Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internal Corrosion Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A851
A854
A860
A861
A862
A864
v
78
80
88
93
94
95
97
97
97
98
99
100
100
102
102
102
102
103
103
104
104
104
104
104
105
105
105
105
105
105
105
106
107
110
111
112
112
112
113
114
114
114
116
116
Table
A842.2.2-1
Chapter IX
B800
B801
B802
B803
B813
B814
B820
B821
B822
B823
B824
B825
B826
B830
B831
B840
B841
B842
B843
B844
B850
Design Factors for Offshore Pipelines, Platform
Piping, and Pipeline Risers . . . . . . . . . . . . . . . . . . . . . . . . . . . .
109
B860
B861
B864
B867
Sour Gas Service
Sour Gas Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope and Intent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sour Gas Terms and Definitions . . . . . . . . . . . . . . . . . . . . . . . . .
Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Material Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Welding Sour Gas Pipelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparation for Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Qualification of Procedures and Welders . . . . . . . . . . . . . . . . .
Preheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stress Relieving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Welding and Inspection Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Piping System Components and Fabrication Details . . . . . .
Piping System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Design, Installation, and Testing . . . . . . . . . . . . . . . . . . . . . . . . .
Steel Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipe-Type and Bottle-Type Holders . . . . . . . . . . . . . . . . . . . . . .
Additional Operating and Maintenance
Considerations Affecting the Safety of Sour Gas
Pipelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipeline Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Location Class and Changes in Number of Buildings
Intended for Human Occupancy . . . . . . . . . . . . . . . . . . . . . .
Corrosion Control of Sour Gas Pipelines . . . . . . . . . . . . . . . . .
External Corrosion Control for Steel Pipelines . . . . . . . . . . . .
Internal Corrosion Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stress Corrosion and Other Phenomena . . . . . . . . . . . . . . . . . .
Tables
B850.1-1
B850.1-2
B850.1-3
B850.1-4
100-ppm ROE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
500-ppm ROE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Metric Example for 100-ppm ROE . . . . . . . . . . . . . . . . . . . . . . .
Metric Example for 500-ppm ROE . . . . . . . . . . . . . . . . . . . . . . .
121
121
121
122
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Numbers and Subjects of Standards and Specifications
That Appear in Mandatory Appendix A . . . . . . . . . . . . . . .
Publications That Do Not Appear in the Code or
Mandatory Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specified Minimum Yield Strength for Steel Pipe
Commonly Used in Piping Systems . . . . . . . . . . . . . . . . . . .
Flexibility and Stress Intensification Factors . . . . . . . . . . . . . .
Extruded Headers and Welded Branch Connections . . . . . .
Testing of Welders Limited to Work on Lines Operating
at Hoop Stresses of Less Than 20% of the Specified
Minimum Yield Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flattening Test for Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
End Preparations for Buttwelding . . . . . . . . . . . . . . . . . . . . . . .
Commonly Used Conversion Factors . . . . . . . . . . . . . . . . . . . .
125
B851
B854
Appendices
Mandatory Appendix A
Mandatory Appendix B
Nonmandatory Appendix C
Mandatory Appendix D
Mandatory Appendix E
Mandatory Appendix F
Mandatory Appendix G
Mandatory Appendix H
Mandatory Appendix I
Nonmandatory Appendix J
vi
117
117
117
117
118
118
118
118
118
118
118
119
119
119
119
119
119
120
120
120
120
121
122
122
122
122
123
129
130
133
136
142
150
151
152
161
Mandatory Appendix K
Nonmandatory Appendix L
Nonmandatory Appendix M
Nonmandatory Appendix N
Nonmandatory Appendix O
Nonmandatory Appendix P
Mandatory Appendix Q
Nonmandatory Appendix R
Criteria for Cathodic Protection . . . . . . . . . . . . . . . . . . . . . . . . .
Determination of Remaining Strength of Corroded
Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Leakage Control Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommended Practice for Hydrostatic Testing of
Pipelines in Place . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparation of Technical Inquiries . . . . . . . . . . . . . . . . . . . . . . .
Nomenclature for Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Estimating Strain in Dents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
vii
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167
168
175
177
178
179
182
183