This paper synthesises for offshore Engineers the result of studies by the present authors and others on the nature of chalking deposits formed on cathodically protected marine structures. Their nature and factors affecting deposition are discussed in relation to the development of cathodic potentials over structures. It is evident that their composition and morphology varies in different seawaters, with their thickness depending upon the cathodic over-potential and the material on which they are formed. The importance of using seawater representative of an operational environment and the suitability of artificial seawater under some circumstances are considered in the context of practical studies of the effect of deposits. Areas of uncertainty which merit further investigation are identified.

Subject
Water, Materials, Offshore structures, Hydroxides, Composition, Cathodic protection, Cathodic potential, Calcium carbonate, Seawater, Current densities, Scale formation, Magnesium, Deposit corrosion
Keywords:
cathodic deposits, chalking, cathodic protection, marine structures, material, potential, seawater
© 1992 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).
1992
Association for Materials Protection and Performance (AMPP)
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