This paper presents the results of full-scale laboratory tests to evaluate the performance of a magnesium ribbon cathodic protection system designed for a large diameter pipeline. Tests were conducted on a 305 cm section of 122 cm OD pipe externally coated with fusion bonded epoxy in a pit filled with various water resistivity environments (5,000, 20,000, and 100,000 ohm-cm). Parameters that were studied included the number of magnesium ribbon anodes connected to the pipe (one to four), coating defect size and shape (discrete or multiple circular defects versus a slit defect that ran the length of the pipe), and the location of anodes with respect to the defect. Full-scale laboratory test results are compared to values predicted by a 2 and 3-dimensional, PC-based computer model that has been developed.

Subject
Water, Piping, Anode potential, Surface defects, Magnesium anodes, Electrolyte resistance, Anode resistance, Defects, Electrical resistivity, Anodic current, Coating defects, Instant off potential, Anodes
© 1995 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).
1995
Association for Materials Protection and Performance (AMPP)
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