Limitations on the use of 13 Cr martensitic stainless steels in sour environments have not been completely defined; however, new evidence from field experience and laboratory tests is presented in this paper that demonstrates that stress-corrosion cracking (SCC) in F6NM stainless steel will occur at high concentrations of H2S with little or no chlorides. The initial findings of SCC in christmas-tree valves in sour-gas service prompted laboratory tests to identify primary environmental contributors to SCC in F6NM. Laboratory tests evaluated the effects of hydrogen sulfide, sulfur, chlorides, temperature, and heat treatment. Hydrogen sulfide and sulfur had the greatest effects on SCC, while chlorides had little effect. It is proposed that SCC occurred by a combined process of localized corrosion and hydrogen embrittlement.

Subject
Embrittlement, Environmental cracking, Sulfur, Hydrogen induced cracking, Corrosion failures, Materials, Valves, Sour environments, Corrosion cracking, Stress cracking, Test environments, Chlorides, Hydrogen
Keywords:
stress-corrosion cracking, hydrogen embrittlement, F6NM stainless steel, hydrogen sulfide, sulfur
© 1991 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).
1991
Association for Materials Protection and Performance (AMPP)
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