Potentiodynamic polarization and linear polarization measurements have been performed on coated and bare pipe steel surfaces in three soils of resistivity ranging from 2,000 to 300,000 ohm- cm. Correction for IR drop effects was employed. The results of these laboratory tests indicate that electrochemical techniques can more clearly identify differences in corrosion resistance than can pipe-to-soil potential measurements and soil resistivity surveys alone. Galvanostatic tests indicated correspondence with Faraday's law when compared with weight loss measurements. A number of different methods for determination of corrosion rates of these materials in soil are compared in this paper. In 14 week tests, a method first described by Oldham and Mansfeld (based upon slight departures from linearity of the polarization curve at low overpotentials) was found, by comparison to weight loss measurements, to be a quantitative method of corrosion rate measurement for pipe steel in soil environments. Preliminary tests showed that A.C. impedance techniques may offer promise for determination of underground corrosion rates also.

Subject
Pipe surfaces, Piping, Corrosion rate, Overpotential, Steel coupons, Impedance, Soil resistivity, Linear polarization, Weight loss, Corrosion resistance, Polarization, Polarization resistance, Soil
© 1983 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).
1983
Association for Materials Protection and Performance (AMPP)
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