During the last 20 years, pressure vessel steels with improved Hydrogen Induced Cracking (HIC) resistance have been developed for H2S environments in oil and gas and refinery equipments. More recently, Stress Oriented Hydrogen Induced Cracking (SOHIC) became a question of great concern, particularly in the refinery industry.

The objective of the paper is to present new results obtained on both normalized and quenched and tempered steels for pressure vessels. Tests have been performed on both parent materials and welded joints. SOHIC resistance has been evaluated through different techniques: Four Point Bend tests and Constant Load tests. Results show that quenched and tempered steels give improved SOHIC resistance in both parent material and HAZ. This improved resistance is due to the bainitic microstructure of the quenched and tempered grade, and to the low hardness of the HAZ even in the as welded condition. A relation between SSC resistance and SOHIC resistance can be established for both grades. Results suggest that SOHIC and SSC in ferrite perlite microstructures are two manifestations of the same phenomena.

Subject
Pressure vessels, Materials, Microstructure, Notches, Stress cracking, Stress, Welded joints, Steel, Stress oriented hydrogen induced cracking, Hydrophobic interaction chromatography, Sulfide stress cracking, Hardness, Quenching and tempering
Keywords:
Stress Oriented Hydrogen Induced Cracking, Sohic, Sulfide Stress Cracking, SSC, Pressure Vessel Steels, Wet H2S environments
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
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