Preferential corrosion at pipeline welds arises primarily from galvanic effects caused by compositional and/or microstructural differences across the weldment. Inhibition can be effective in mitigating preferential attack but, under certain circumstances, inhibitors can exacerbate the problem. This paper emphasises the importance of simulating appropriate hydrodynamic conditions at the weldment surface in tests to evaluate the effects of inhibitors. The use of three test systems; an ambient pressure rotating cylinder electrode cell, a jet impingment rig and a high pressure rotating cylinder vessel, are described. The relative merits of each type of system are described and typical test results are used to illustrate different effects of inhibitors on weldment corrosion.

Subject
Weld attack, Cylinders, Corrosion rate, Wall shear stress, Hydrodynamics, Ambient barometric pressure, Stress, Shear, Jet impingement, Corrosion inhibitors, Electrodes, Weld metal, Weldment
Keywords:
Inhibition, welds, carbon dioxide, hydrodynamics, laboratory testing
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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