An investigation of a recent pre-1970 ERW Pipe Seam Weld Failure incident is presented. The investigation uses an interdisciplinary approach that combines metallurgical and fractographic analysis, fracture mechanics testing, as well as failure analysis diagram to determine the origin and nature of the failure, the initial and final size of the flaw that causes the failure, the fracture toughness of the base-metal, HAZ, and seam weld, and the critical conditions for the failure. The paper summarizes the findings of the investigation and compares the analysis with the observed failure. In addition, fatigue analysis is performed based on the pressure cyclic data for understanding the reasons of the sub-critical crack growth observed. The findings of the study suggest that future ILI inspections should have a capability of detecting small defects with appropriate excavation and mitigation plans to account for tool uncertainty and ensure future integrity of the pipeline.

Subject
Seams, Crack growth, Corrosion fatigue, Piping, Fracture toughness, Charpy impact test, Crack initiation, Pipelines, Inspection, Failure analysis, Mechanical failure, Defects, Toughness
Keywords:
ERW seam failure, failure analysis, crack initiation, subcritical crack growth, fatigue, cleavage, FAD analysis, life estimate
© 2008 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2008
Association for Materials Protection and Performance (AMPP)
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