Coatings and cathodic protection are required to minimize external corrosion on pipelines, flowlines, and tiebacks. For years cathodic protection systems have been designed to industry standards, which generally require bracelet anodes at a frequency of 6-12 pipe joints. In recent years improvements in subsea pipeline technology have often made this approach less than optimal. Deepwater subsea flowlines / tiebacks and pipe with high-integrity coatings often benefit from increased distances between anodes. In some cases it may be desirable to use remote voltage sources in-lieu of bracelets. Recently a voltage and current attenuation method has been developed and implemented to model such design approaches. The model is an improvement on earlier theory, including the capability to model systems with many voltage sources at variable potentials and distances. In addition the model has been developed to analyze systems comprised of multiple coating systems and materials, such as a combination flexible / rigid-pipe deepwater tieback. Theory and basis of this approach, industry examples, and methods for monitoring and verification are presented.

Subject
Voltage drops, Anode potential, Cathodic protection, Pipelines, Electrolyte resistance, Flowlines, Anode resistance, Electrical resistivity, Anodic current, Bracelet anodes, Attenuation, Polarization resistance, Anodes
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
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