Unlike sour gas pipelines the transmission of sour crude oil must take into consideration the effects of cyclic (fatigue) loading resulting from normal operating conditions as well as from sporadic periods of pressure surge.

The significance of flaws in the weld toe region of double submerged-arc welded large diameter line pipe was studied utilizing laboratory and full-scale testing methods. The laboratory test program characterized the critical crack size using the fracture mechanics parameter, KISCC, as well as predicted sub-critical crack growth rate using a Paris exponential function.

To compliment the laboratory tests, full-scale experiments were conducted using sour crude oil and cyclic loading conditions that represented a 40 year life of the pipeline. Monitoring of weld toe indications was accomplished by ultrasonic inspection techniques.

Correlation of laboratory with full-scale testing data confirmed that the life of sour crude oil pipelines can be predicted using fracture mechanics concepts.

Subject
Test methods, Crack growth, Corrosion fatigue, Stress intensity, Pipelines, Fatigue crack growth rate, Stress cracking, Crack depth, Flaws, Crude, Stress corrosion cracking, Fracture mechanics, Oil
© 1988 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).
1988
Association for Materials Protection and Performance (AMPP)
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