An S31803 (22-05 alloy) duplex stainless steel flow-cross in service in the H2S-containing Saint-Faust gas field near Lacq was almost broken in two by a corrosion crack resulting from improper heat treatment. Sensitization had occurred much more rapidly than expected from the kinetics of sigma phase formation generally considered in the literature. None of the inspection techniques routinely employed in the oil and gas industry would have been capable of detecting this manufacturing defect. More stringent quality acceptance criteria are therefore necessary.

Subject
Sigma phase, Materials, Pitting temperature, Hydrogen content, Ferric chloride, Corrosion cracking, Corrosion detection, Mechanical failure, Defects, Sensitization, Duplex stainless steel, Ferrite, Heat treatment
Keywords:
Duplex stainless steel, UNS S31803, H2S, Uranus 50, waterflood, sigma phase, sensitization, sigmatization
© 1997 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).
1997
Association for Materials Protection and Performance (AMPP)
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