Alloy T-91 (modified 9 Cr - 1 Mo steel) is being specified for coker charge heater tubulars. This alloy, not normally used in petroleum refining service, is characterized by lower ductility and higher strength/hardness than is exhibited by the standard 9 Cr - 1 Mo steel alloy. Modified 9 Cr - 1 Mo steel alloy was subjected to detailed mechanical property assessment, sulfide stress corrosion cracking susceptibility and fracture toughness tests. Results showed that hardness of the tube welds exceeded the range normally used in wet H2S service, the weld and HAZ toughness are low, and the sulfide cracking susceptibility is very high. Furthermore, once cracked the crack growth rate increases significantly from wet H2S exposure.

Subject
Materials, Heaters, Tubes, Weldments, Welding, Coke, Steam, Sulfide stress cracking, Post weld heat treatment, Hardness, Heat treatment, Stress corrosion cracking, High temperature
Keywords:
low alloy steels, sulfide stress corrosion cracking, weld hardness, refinery heater tubes, cokers
© 1996 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).
1996
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.