A 16 inch, diameter LNG pipeline which transports 54 MBPD between extraction and fractionation facilities located north-east of Venezuela, showed an accelerated external corrosion even though coating and cathodic protection had been used to protect it.

A diagnosis of the external condition of the pipeline was addressed by matching the results obtained by using different techniques such as electromagnetic pigging, DC voltage gradient survey, close interval potential survey, soil classification and resistivity profiles along the pipeline.

This paper discusses the factors evaluated to identify sections of the pipe where corrosion problems occurred under disbonded pipeline coating, which required immediate attention for coating rehabilitation.

Subject
Piping, Cathodic protection, Pipeline sections, Pipe to soil potential, Pipelines, Soil resistivity, Coating surveys, Corrosion detection, External corrosion, Coating defects, Surveys, Instant off potential, Soil
Keywords:
underground corrosion, tape coating, cathodic protection, cathodic disbonding, coating quality, soil stress
© 1998 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).
1998
Association for Materials Protection and Performance (AMPP)
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