Standard Toughness Requirements for Piping

ASME Code for Pressure Piping, B31

AN A MERICAN NA TIONAL S T AND ARD

ASME B31T-2018

(Revision of ASME B31T-2015)

ASME B31T-2018

(Revision of ASME B31T-2015)

Standard

Toughness Requirements for Piping

ASME Code for Pressure Piping, B31

AN AMERICAN NATIONAL STANDARD

Date of Issuance: February 14, 2019

The next edition of this Code is scheduled for publication in 2021.

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CONTENTS

Foreword iv

Committee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Correspondence With the B31 Committee vi

Summary of Changes viii

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3 Low-Temperature Ranges and Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

4 Impact Testing Methods and Acceptance Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

FOREWORD

In 2000, the ASME B31 Code for Pressure Piping, Materials Technical Committee (MTC) determined that there was a need to develop a standard set of toughness requirements for piping components that can be adopted by reference by the various piping codes and other codes and standards. At the time, the requirements of the ASME B31 Code books varied, with some having no requirements at all.

This Code is intended to provide requirements for evaluating the suitability of materials used in piping systems for piping that may be subject to brittle failure due to low-temperature service conditions.

Under direction of ASME Standards and Certification, both SI and U.S. Customary units are provided. The 2010 edition of this Code was approved by the American National Standards Institute (ANSI) on April 20, 2010.

The 2015 edition of the Code was approved by ANSI on October 21, 2015. The 2018 edition of the Code was approved by ANSI on December 6, 2018.

ASME B31 COMMITTEE

Code for Pressure Piping

(The following is the roster of the Committee at the time of the approval of this Code.)

STANDARDS COMMITTEE OFFICERS

J. E. Meyer, Chair

J. W. Frey, Vice Chair

1. P. Maslowski, Secretary

STANDARDS COMMITTEE PERSONNEL

R. J. T. Appleby, ExxonMobil Pipeline Co.

C. Becht IV, Becht Engineering Co., Inc.

K. C. Bodenhamer, TRC Pipeline Services

R. Bojarczuk, ExxonMobil Research and Engineering Co.

M. R. Braz, MRBraz & Associates, PLLC

J. S. Chin, TransCanada Pipeline US

D. D. Christian, Victaulic

R. P. Deubler, Becht Engineering Co., Inc.

D. Diehl, Hexagon PPM

1. Eskridge, Jr., Jacobs Engineering

2. J. Fetzner, BP Exploration Alaska, Inc.

P. D. Flenner, Flenner Engineering Services

J. W. Frey, Joe W. Frey Engineering Services, LLC

D. R. Frikken, Becht Engineering Co., Inc.

R. A. Grichuk, Fluor Enterprises, Inc.

R. W. Haupt, Pressure Piping Engineering Associates, Inc.

L. E. Hayden, Jr., Consultant

G. A. Jolly, Samshin Ltd.

K. Kaplan, Consultant

C. Kolovich, Consultant

A. Livingston, Kinder Morgan

A. P. Maslowski, The American Society of Mechanical Engineers

W. J. Mauro, American Electric Power

J. E. Meyer, Louis Perry Group

T. Monday, Team Industries, Inc.

M. L. Nayyar, NICE

G. R. Petru, Acapella Engineering Services, LLC

D. W. Rahoi, CCM 2000

R. Reamey, Turner Industries Group, LLC

M. J. Rosenfeld, Kiefner/Applus Global

J. T. Schmitz, Southwest Gas Corp.

S. K. Sinha, Lucius Pitkin, Inc.

W. J. Sperko, Sperko Engineering Services, Inc.

J. Swezy, Jr., Boiler Code Tech, LLC

F. W. Tatar, FM Global

K. A. Vilminot, Commonwealth Associates, Inc.

J. S. Willis, Page Southerland Page, Inc.

MATERIALS TECHNICAL COMMITTEE

R. P. Deubler, Chair, Becht Engineering Co., Inc.

C. Eskridge, Jr., Vice Chair, Jacobs Engineering

C. E. O’Brien, Secretary, The American Society of Mechanical Engineers

B. Bounds, Bechtel Corp.

W. P. Collins, WPC Solutions, LLC

R. A. Grichuk, Fluor Enterprises, Inc.

J. Gundlach, Michigan Seamless Tube, LLC

A. A. Hassan, Power Generation Engineering and Services Co.

L. Henderson, Jr., Chiyoda International Corp.

C. Henley, Kiewit Engineering Group, Inc.

G. A. Jolly, Samshin Ltd.

C. J. Melo, S & B Engineers and Constructors Ltd.

M. L. Nayyar, NICE

D. W. Rahoi, CCM 2000

R. A. Schmidt, Canadoil Forge

Z. Djilali, Contributing Member, Sonatrach

J. L. Smith, Contributing Member, Consultant

CORRESPONDENCE WITH THE B31 COMMITTEE

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Secretary, B31 Standards Committee

The American Society of Mechanical Engineers Two Park Avenue

New York, NY 10016-5990

https://go.asme.org/Inquiry

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ASME B31T-2018 SUMMARY OF CHANGES

Following approval by the ASME B31 Committee and ASME, and after public review, ASME B31T-2018 was approved by the American National Standards Institute on December 6, 2018.

ASME B31T-2018 includes the following changes identified by a margin note, (18).

Notes (2) and (3), respectively

21 Table 3.2-1 (1) Second and third columns merged

(2) Fifth A194, second A420, third A671, third A672, and first “Various” entries revised

−325 entries revised

1. Third SS −60 entry deleted

2. Last SS −60 entry added

ASME B31T-2018

STANDARD TOUGHNESS REQUIREMENTS FOR PIPING

1. INTRODUCTION

   This Code provides requirements for evaluating the suitability of materials used in piping systems for piping that may be subject to brittle failure due to low-temperature service conditions. While low-tempera- ture 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 “low-temperature service” as used in this Code, there- fore, varies widely across the many applications for which piping systems are used. 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).1 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 Code has been established to provide uniform guidance

   in this area. This Code may be invoked in whole or in part by various piping codes and/or specifications and is only mandatory when so invoked.

   Suitability of piping systems for low-temperature service is a function of several variables, including mate- rial properties, design loadings, and fabrication proce- dures. The three primary factors that generally control the susceptibility for brittle fracture are material tough- ness, crack size, and tensile stress level. There are a wide variety of services in which low-temperature suitability need not even be considered; however, a screening criterion is necessary to determine this.

   One objective of this Code is to provide a simple approach to evaluate whether additional consideration is necessary to evaluate suitability for low-temperature service. This is done by establishing a low-temperature service limit for various materials. Services at or warmer than this limit are not considered low tempera- ture, and additional considerations relative to suitability are not required.

   For services colder than this limit, various requirements are provided that, when met, qualify the material for low- temperature services. These requirements include impact testing, qualification of welding and other fabrication procedures, and limiting the design loadings.

   The low-temperature service limit established herein is based on a reasonable degree of assurance that at this temperature the material will have a ductile failure mode. The actual ductile-to-brittle transition temperature

   
   

   
   

   1 For guidance on cryogenic valves, refer to MSS SP-134, Valves for Cryogenic Service Including Requirements for Body/Bonnet Extensions.

   for a given material specification will vary based on actual heat chemistry of the material and subsequent processing. For critical applications, the design engineer can select materials with a lower low-temperature service limit or require impact testing. On less-critical applications, material with a higher low-temperature service limit may be acceptable. The final selection is left to the refer- ring code and the design engineer (when permitted by the referring code).

   To keep the number of sets of requirements to a minimum, material groupings have been established, and a unique set of requirements has been provided for each group. These groups are assigned “T- numbers” for easy reference. Although most materials used in piping systems are listed, some are not, and these unlisted materials are not addressed in this Code. Where permitted by the code or specification invoking this Code, these requirements may be used for unlisted materials. The invoking code or specification may establish the correct T-number group for the material or may invoke the testing and other requirements of this Code using the worst-case assumption that the design minimum temperature is colder than the temperatures that would allow exemption from any of the requirements of this Code. The guidelines for establishing the correct T- number group are provided in Nonmandatory Appendix B.

   
   

2. GLOSSARY

CVN: the abbreviation for Charpy V-notch.

design minimum temperature: the lowest component temperature expected in service.

fully deoxidized steel: steel that has been deoxidized, either by the addition of strong deoxidizing agents or by vacuum treatment, to reduce the oxygen content to such a level that no reaction occurs between the carbon and oxygen during solidification. Also known as killed steel. Steels that are not fully deoxidized include rimmed, semi-killed, and capped steels. Limitations on the use of steels that are not fully deoxidized may be imposed by the applicable piping code or specification.

lower critical temperature: the temperature at which the first phase change occurs when heating a metal.

low-temperature service limit: the design minimum temperature at which additional requirements for low- temperature service do not apply.

NDT temperature: the nil ductility transition temperature.

stress ratio: the ratio of the design stress to an allowable stress. (See para. 3.6.2.)

1