There have been several instances where water purified from seawater by reverse osmosis has caused accelerated corrosion of carbon steel pipes. Therefore research was undertaken to determine the corrosion rate of low carbon steel in water with different contaminants, with and without aeration, and at different velocities.

The results show that in high purity deionized (DI) water with oxygen, the corrosion rates were initially very high but dropped rapidly within a few hours to <100μm/yr. In jet impingement of DI water with oxygen, the corrosion rates dropped even lower, approaching zero, because the steel surface passivated.

Water analysis from the reverse osmosis units from the offshore oil drilling platforms showed that reverse osmosis units would typically leave behind many ppm of NaCl and Na2SO4. Therefore laboratory tests were conducted and it was found that adding NaCl and Na2SO4 to the DI water, increased the corrosion rate, proportionally to the concentration. In the jet impingement tests with contaminated water containing oxygen, the corrosion rate of the steel was ~5 mm/yr, beneath a thick, gelatinous, ferric hydroxide film. When the same jet impingement tests were conducted with high purity DI water saturated with oxygen, the corrosion rate was zero, due to the steel surface passivating.

Subject
Steel surfaces, Water, Composition, Corrosion rate, Steel coupons, Sulfates, Sodium chloride, Purity, Jet impingement, Steel, Oxygen, Immersion, Chlorides
Keywords:
purified water, velocity, jet impingement, steel, corrosion rate
© 2012 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).
2012
Association for Materials Protection and Performance (AMPP)
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