ASME B31.

9-2014
(Revision of ASME B31.9-2011)

Building
Services Piping
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 B31.9-2014
(Revision of ASME B31.9-2011)

Building
Services Piping
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

Two Park Avenue New York, NY 10016 USA

 Date of Issuance: April 28, 2014

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Copyright 2014 by
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 CONTENTS

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Committee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
Summary of Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x
Chapter I Scope and Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
900 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter II Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Part 1 Conditions and Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
901 Design Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
902 Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Part 2 Pressure Design of Piping Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
903 Criteria for Pressure Design of Piping Components . . . . . . . . . . . . . . . . . . . . . . . . 11
904 Pressure Design of Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Part 3 Selection and Limitation of Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
905 Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
906 Fittings, Bends, and Intersections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
907 Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
908 Flanges, Blanks, Gaskets, and Bolting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Part 4 Selection and Limitation of Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
910 Piping Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
911 Welded Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
912 Flanged Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
913 Mechanical and Proprietary Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
914 Threaded Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
915 Flared, Flareless, and Compression Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
916 Bell and Spigot Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
917 Brazed and Soldered Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Part 5 Expansion, Flexibility, and Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
919 Expansion and Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
920 Loads on Pipe-Supporting Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
921 Design of Pipe-Supporting Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Part 6 Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
922 Design Requirements Pertaining to Specific Piping Systems . . . . . . . . . . . . . . . . 25
Chapter III Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
923 Materials General Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Chapter IV Component Requirements and Standard Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
926 Dimensions and Ratings of Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Chapter V Fabrication, Assembly, and Erection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
927 Welded Fabrication of Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
928 Brazing and Soldering of Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
929 Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
930 Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
931 Heat Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
934 Fabrication of Nonmetals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
935 Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

iii
Chapter VI Inspection, Examination, and Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
936 Inspection and Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
937 Leak Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figures
900.1.2 Code Jurisdictional Limits for Piping Drum-Type Boilers . . . . . . . . . . . . . . . . 2
904.2.2 Nomenclature for Miter Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
921.1.3-1 Support Spans for Standard Wall Steel Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
921.1.3-2 Support Spans for Copper and Thermoplastic Pipe . . . . . . . . . . . . . . . . . . . . . . . . . 23
927.4.3-1 Fillet Weld Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
927.4.3-2 Minimum Weld Size, Setback, and Depth of Insertion for Slip-On and
Socket Weld Flanges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
927.4.3-3 Minimum Welding Dimensions for Socket-Welding Components Other Than
Flanges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
927.4.5-1 Acceptable Welds for Flat Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
927.4.5-2 Unacceptable Welds for Flat Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
927.4.6-1 Typical Weld Branch Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
927.4.6-2 Typical Weld Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Tables
902.4.3 Joint Factors, E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
904.2.1 Pipe Thickness for Bends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
917.3 Rated Internal Working Pressures of Joints Made With Copper Water
Tube and Solder Joint Fittings, psig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
919.3.1 Moduli of Elasticity and Thermal Expansion Coefficients . . . . . . . . . . . . . . . . . . . 18
921.2.2 Capacities of Threaded ASTM A36 Steel Rods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
926.1 Component Standards and Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
926.2 Standard Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Mandatory Appendices
I Stress Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
II Allowable Pressures for Nonmetallic, Nonplastic Pressure Piping . . . . . . . . . . . 57
III Reference Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
IV Preparation of Technical Inquiries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Nonmandatory Appendices
A Nonmandatory Quality System Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
B Seismic Design and Retrofit of Piping Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

iv