Previous tests showed type 316 stainless compression fittings can crack when exposed to NACE TM0177 solution at elevated temperatures for 30 days. Following up this finding, one-month, three-month and twelve month tests have been conducted on type 316 compression fittings and instrumentation tubing in order to assess their suitability for sour service. Loops were constructed, containing a total of over three hundred fittings from four manufacturers and filled with sour fluids comprising high chloride content solutions. They were pressurised to 50 bara (5MPa) with CO2 and H2S partial pressures in the range 0 - 0.8 bara (8kPa) and maintained at temperatures in the range 60 - 120°C. The tests showed that, even in mildly sour conditions, at elevated service temperatures cracking can occur and that the threshold H2S partial pressure decreases with increasing temperature.

Subject
Intergranular stress corrosion cracking, Manufacturing, Compression, Tubes, Fittings, Leaks, Corrosion cracking, Machining, Intergranular cracking, Tubing, Cracking, Hardness, Stress corrosion cracking
Keywords:
sulfide stress cracking, austenitic stainless steels, compression fittings
© 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)
You do not currently have access to this content.