This paper briefly describes a failure of 22Cr duplex stainless steel pipework on an offshore platform in the North Sea (UK). The pipework carried a condensate/water stream at approx. 140 °C. The details and results of the test programme that was subsequently carried out to clarify the internal cracking mechanism are presented. There was very little, if any, oxygen in the process stream and it was concluded that the cause of failure was chloride concentration to extremely high levels due to an evaporation process. The test programme established acceptable limits in terms of temperature, chloride and oxygen content for the 22Cr steel and also examined 25Cr duplex and alloy 625.

Subject
Test methods, Materials, Evaporation, Nickel based alloys, Corrosion cracking, Intergranular cracking, Brines, Oxygen, Four point bend testing, Cracking, Chlorides, Stress corrosion cracking, Chloride stress corrosion cracking
Keywords:
Duplex stainless steels, alloy 625, chloride stress corrosion cracking, concentration effect
© 2005 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).
2005
Association for Materials Protection and Performance (AMPP)
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