In a 1998 study, costs for corrosion in USA were estimated to be about 276 billion US-$. Even if the complete corrosion costs cannot be avoided; corrosion experts think that by choosing the right corrosion control technology including better materials of construction, these costs can be reduced by 25 to 30%[1].

One way to reduce this gigantic amount of money is to use components constructed out of high alloy stainless steels and nickel alloys. Modern stainless steels and nickel alloys have excellent resistance to various forms of corrosion (localized corrosion and stress corrosion cracking) in corrosive environments like seawater, brines, oil and sour gas wells. The corrosion resistance of an alloy is primarily related to its nickel, chromium, molybdenum and nitrogen content. This is often expressed by the so-called PRE-number (Pitting Resistance Equivalent). Higher nickel is beneficial for resisting chloride stress corrosion cracking and sulphide stress corrosion cracking whereas Cr, Mo, W (to lesser degree) and nitrogen contribute to localized corrosion resistance.

Another prerequisite for materials in the oil & gas industry is the NACE MR0175/ ISO 15156 standard requirements. These standards show the suitability of a material in sour gas conditions regarding their stress corrosion cracking resistance under various conditions of temperature, pH, partial pressure of H2S and CO2, chlorides content etc.

This present paper reviews the materials (solid and cladded) currently used in the oil & gas industry. The applications and corrosion resistance of Alloy 926 (UNS N08926), Alloy 31 (UNS N08031), Alloy 59 (UNS N06059), Alloy 825 (UNS N08825), Alloy 625 (UNS N06625), Alloy 718 (UNS N07718), Alloy 925 (UNS N09925) and Alloy K500 (UNS N05500) for various components are briefly described and compared in order to point out the performance benefits of these materials in oil & gas environments.

Subject
Marine environments, Materials, Corrosion resistant alloys, Stainless alloys, Nickel based alloys, Tubes, Molybdenum alloys, Sour gas, Crevice corrosion, Pitting, Corrosion resistance, Stainless steel, Titanium alloys
Keywords:
Oil & Gas, Nickel Alloy, Alloy 926 (UNS N08926), Alloy 31 (UNS N08031), Alloy 59 (UNS N06059), Alloy 825 (UNS N08825), Alloy 625 (UNS N06625), Alloy 718 (UNS N07718), Alloy 925 (UNS N09925), Alloy K500 (UNS N05500)
© 2008 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).
2008
Association for Materials Protection and Performance (AMPP)
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