Transgranular stress corrosion cracking (TGSCC) of buried carbon steel fuel transmission pipelines has been reported to occur on pipelines that are protectively coated and subjected to cathodic protection. The objective of this research was to investigate the conditions under which near-neutral pH environments can be formed. Specifically, this research focuses on how the pH of solutions change with applied potential and CO2 exposure. Potentiodynamic polarization tests were performed in solutions with different ground water constituents to see their role in anodic and cathodic behavior of pipeline steels. Application of cathodic protection alters the pH at the steel surface, shifting the environment outside of near-neutral pH conditions. Coupon exposure tests and potentiodynamic results suggest that the environment of TGSCC is possible in a wide range of temperatures and compositions.

Subject
Pipe surfaces, Steel surfaces, Cathodic protection, Cathodic potential, Pipelines, Bicarbonates, Transgranular stress corrosion cracking, Acidity, Steel, Carbon dioxide, Soil, Corrosion potential, Hydrogen
Keywords:
Near-Neutral Stress Corrosion Cracking (NNSCC), Transgranular Stress Corrosion Cracking (TGSCC), pipeline steel, bicarbonate solutions, simulated groundwater
© 2007 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).
2007
Association for Materials Protection and Performance (AMPP)
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