The quality of the indirect inspection data is a critical factor in conducting a successful ECDA program. New NACE standards (SP0207-20071 and TM 0109-092), improved instrumentation, experience sharing, and extensive training during the last several years, has resulted in a significant improvement in the accuracy of the survey data.

This paper covers a number of lessons learned by dealing with less-known sources of measurement error, during six years of ECDA application on more than 50 gas pipelines in Ontario.

Topics addressed include a discussion of errors;

  • generated by rectifying elements in current interrupters,

  • caused by the influence of remote rectifiers,

  • introduced by local changes in soil resistivity during the DC Voltage Gradient Survey, and

  • produced by transient currents during the Close Interval Potential Survey.

Subject
Electric current, Piping, Voltage, Pipe to soil potential, Chainage, Magnesium anodes, Pipelines, Soil resistivity, Potential measurements, Rectifiers, Surveys, Remote earth, Electrode potential
Keywords:
ECDA, CIPS, DCVG, HVAC powerlines, influence survey, transient currents
© 2010 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).
2010
Association for Materials Protection and Performance (AMPP)
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