Several failures of Type 410 stainless steel (SS) and CA6NM components in sweet and sour gas well service are reviewed. The sweet corrosion resistance of Type 410 SS wellhead components was exceeded due to high flow velocities and turbulence, resulting in rapid attack. This equipment also simultaneously suffered crevice corrosion in service. A high hardness Type 410 SS subsurface safety valve experienced hydrogen stress-cracking in the absence of H2S when exposed to a brine completion fluid. Finally, sulfide stress-cracking failure of a CA6NM wellhead valve was attributed to a weld repair made prior to final heat treatment. In this case, weld metal chemistry variation resulted in insufficient temper softening, despite the fact that low hardness was obtained in the valve base metal. The failures discussed further define the limitations of martensitic stainless steels used for corrosive gas production and indicate that additional precautions are necessary to assure failure-free performance.

Subject
Corrosion failures, Valves, Fracture surfaces, Corrosion cracking, Wellheads, Repair, Fluids, Housing, Brines, Pitting, Corrosion resistance, Sulfide stress cracking, Hardness
© 1988 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).
1988
Association for Materials Protection and Performance (AMPP)
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