B31T - 2010 Standard Toughness Requirements for Piping

This Standard provides requirements for evaluating the suitability of materials used in piping systems for piping that may be subject to brittle failure due to lowtemperature service conditions. While low-temperature service is usually considered to be below ambient temperature, brittle failure can occur at temperatures above ambient temperature for certain combinations of materials, thicknesses, and stress levels. The definition of “lowtemperature service” as used in this Standard, therefore, varies widely across the many applications for which piping systems are utilized. For a building service air line, low temperature may be 0°C (32°F), whereas for a cryogenic piping system, it could easily be -185°C (-300°F). However, the principles used to evaluate the suitability of a piping system as related to service temperature by evaluating the toughness of the material can be applied across a wide temperature range, and this Standard has been established to provide uniform guidance in this area. This Standard may be invoked in whole or in part by various piping codes and/or specifications and is only mandatory when so invoked.

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Contents of this Code

Foreword
Committee Roster
Correspondence With the B31 Committee

1 Introduction
 2 Glossary
3 Low-Temperature Ranges and Requirements
4 Impact Testing Methods and Acceptance Criteria

Tables
3.1-1 Low-Temperature Service Requirements by Material Group
3.2-1 Material Groupings by Material Specification 20
4.4.2-1 Charpy Impact Test (Absorbed Energy) Temperature Reduction for Material or Specimens < 10 mm (0.394 in.)
4.5.1-1 Minimum Required Charpy V-Notch Impact Values

Mandatory Appendices
I Temperature Thickness Curves 27
II Stress Ratio Curves 31
III Material Groupings by T-Number

Nonmandatory Appendices
A Flowchart of Requirements 40
B Guidelines for Establishing T-Number Group

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