It is well-known that the corrosion behaviour of stainless steels and nickel-base alloys varies to different seawaters. Decisive for this phenomenon are differences in temperature, salinity, marine life (bacteria and their decomposition products). Therefore, longtime tests have been performed in a test loop with natural seawater of the German North Sea.

The investigations include sheet samples with a special crevice assembly and weldments as well as loop test arrangements with pipe couplings. The seawater temperature was adjusted to 50 and 70°C. All materials were also tested as rotating disc electrodes at various temperatures up to 90°C and different revolutions in artificial seawater.

The results allow to predict the behaviour of a number of materials in German North Sea-water under actual service conditions.

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    Alloy 24 allows design of light weight offshore structures.

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    Alloy N08031 is recommended for construction of heat-exchangers and process coolers.

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    None of the tested alloys suffered from stress corrosion cracking.

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    Optimum cost/performance ratio is provided by alloys N08926, 24 and N08031.

Subject
Weld attack, Materials, Piping, Corrosion resistant alloys, Stainless alloys, Nickel based alloys, Corrosion attacks, Crevice corrosion, Pitting, Corrosion resistance, Stainless steel, Alloys, Electrodes
Keywords:
Austenitic stainless steels, nickel-base alloys, filler metal, welding, North Sea-water, looptests, elevated temperature, rotating disc electrode, crevice corrosion, pitting corrosion
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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