The correlation of cathodic disbondment results on pipeline coatings obtained in laboratory tests such as the standard ASTM or DIN procedures with actual in-ground performance is necessary in order to determine the uselfullness of the data.

In this work, the cathodic disbandment of tape wrap coatings is measured in the laboratory in three ways: First, on steel coupons; second, according to ASTM G-8; and third, in an apparatus designed to simulate soil burial at any desired depth. The soil simulation apparatus uses a rubber membrane surrounding the soil sample which in turn surrounds the coated pipe sample. The membrane can be pressurized by air to 1-10 psi (6.9-69 kPa) which effectively simulates burial depths of about 6-12 feet (2-4 meters).

The data for the rate of cathodic disbondment measured in the laboratory tests are compared to data from an outdoor test site for the direct burial of samples.

The data show the rate of disbondment is slowest for direct soil burial, next slowest for the laboratory soil simulation, and fastest for the laboratory electrolyte test. The laboratory test data show the rate is very dependent on the restraining pressure, especially at elevated temperatures.

Subject
Holidays, Piping, Modeling, Sand, Tape, Laboratory data, Pipelines, Cathodic disbondment, Disbondment, Cathodic sites, Rubber, Soil, Electrolytes
© 1986 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).
1986
Association for Materials Protection and Performance (AMPP)
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