Past methods of calculating cathodic protection (CP) current distribution have been limited to relatively simple systems of symmetrical geometry in which the cathode is not allowed to polarize. Quantitative predictions of current distribution on offshore structures are impossible without applying computer methods capable of handling complex, nonuniform fields and nonlinear polarization characteristics. Present CP design techniques, based on overall "average" design current density values, do not address current distribution and thereby tend to be conservative.

A quantitative method using a finite element computer technique is described for predicting the distribution of CP current on complex structures. The method considers the numerous variables affecting current distribution.

Finite element models of offshore structures are shown, and, to demonstrate the process of current distribution, a simple structural member joint is analyzed. Critical local current density is defined, and time interval current density and potential profiles are shown. Results demonstrate that substantial cost and weight savings are possible by optimizing CP designs through computer techniques.

Subject
Cathodes, Electric current, Costs, Offshore structures, Finite element analysis, Current densities, Current distribution, Anodic current, Steel, Electric potential, Elements, Polarization, Anodes
© 1982 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).
1982
Association for Materials Protection and Performance (AMPP)
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