The criteria for cathodic protection of buried pipelines offshore are often not clearly defined. In order to study some aspects of cathodic protection of steel in the buried state a cell has been designed to determine corrosion control parameters. The tests have been performed with high strength steel exposed to an anaerobic mud potentiostatically polarised in the range -770 to -970 mV (Cu/CuSO4). The exposure period lasted 6 months and tests were performed at a constant temperature of 5°C and also at 30°C. The mud used is compared to the properties of the superficial North Sea sediments. Some geochemical properties of the anaerobic North Sea sediments are discussed in terms of corrosion control. In the mud system an adequate cathodic protection potential of -950 mV (Cu/CuSO4) gives a residual corrosion equivalent to about 6 mA/m2. The current density for protection will vary with time due to the unstable nature of the ferrous sulphide scale. Integrated over the exposure period the average current density for an adequate protection was found to be 45 mA/m2 and 120 mA/m2 at 5° and 30°C respectively.

Subject
Electrochemical cells, Cathodic protection, Sand, Corrosion rate, Iron sulfides, Drilling fluid, Sediments, Minerals, Current densities, Steel, Corrosion protection, Sulfides, Samples
© 1981 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).
1981
Association for Materials Protection and Performance (AMPP)
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