Power line fault current coupling to buried pipelines is examined. Inductive and conductive coupling mechanisms are reviewed. A simple model for pipe coating impedance behavior under fault conditions is presented. In general, coating impedance is reduced during the fault, thus decreasing the induced voltage level.

High voltage tests on several types of coating were made. It was found that incipient coating damage, e.g. a decrease in coating resistance which was not completely reversible, could occur at applied voltage levels as low as 3000 volts. Puncture levels for organic coatings were in the 4000-7000 volt range. Fusion bonded epoxy was found to have a considerably higher dielectric strength of approximately one kv/mil thickness. Ionization of the electrolyte at holiday sites was found to be a significant factor in causing a decrease in the coating resistance.

Subject
Holidays, Electric current, Piping, Voltage, Couplings, Impedance, Pipelines, Ionization, Towers, Electrical resistance, Soil, Electrolytes, Fault currents
© 1990 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).
1990
Association for Materials Protection and Performance (AMPP)
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