Basics of Metal Fatigue in Natural Gas Pipeline Systems — A Primer for Gas Pipeline Operators

The contents of this report are published as received from Kiefner and Associates, Inc. The opinions, findings, and conclusions expressed in the report are those of the authors and not necessarily those of PRCI, its member companies, or their representatives. Publication and dissemination of this report by PRCI should not be considered an endorsement by PRCI or Kiefner and Associates, Inc, or the accuracy or validity of any opinions, findings, or conclusions expressed herein. In publishing this report, PRCI makes no warranty or representation, expressed or implied, with respect to the accuracy, completeness, usefulness, or fitness for purpose of the information contained herein, or that the use of any information, method, process, or apparatus disclosed in this report may not infringe on privately owned rights. PRCI assumes no liability with respect to the use of , or for damages resulting from the use of, any information, method, process, or apparatus disclosed in this report. The text of this publication, or any part thereof, may not be reproduced or transmitted in any form by any means, electronic or mechanical, including photocopying, recording, storage in an information retrieval system, or otherwise, without the prior, written approval of PRCI. " ACKNOWLEDGEMENT The authors wish to thank the following members of the PRCI technical committee for their thorough and thoughtful reviews: In addition, the authors wish to thank the following individuals for their expert review and comments: Occasionally and under certain circumstances, fatigue may constitute a potential threat to the integrity of some pipelines. Part 192, Subpart O, " Implementing Integrity Management " , Paragraph 192.917(e)(2) requires an operator to address the threat of " cyclic fatigue ". This document explores the questions " What is fatigue? " , " Where can it occur in a gas pipeline facility? " , and " What can be done about it? " The objective is to provide operators and others interested in natural gas pipeline safety with a useful understanding of the extent to which fatigue could pose a legitimate and actionable safety threat, as well as to demonstrate the authors' opinion that in most respects, fatigue remains a comparatively minor risk component of the overall spectrum of threats to natural gas pipeline safety. Basic considerations of fatigue, physical testing of pipe, and operating experience have shown that fatigue due to pressure cycles is not a limiting factor on the service life of sound pipe free …