When fluid enters a pipeline or a piece of equipment, or goes over an obstacle in its flow path, a new boundary layer is developed, which increases the rate of local corrosion. This new local rate of corrosion can be calculated from the boundary layer theory and the theory of mass transfer. The calculated rate of local corrosion varies from a fraction of mm/year to 1 mm/year or more, depending on the location, hydrodynamics, and temperature. The calculations show that there are two locations showing a high rate of local corrosion. The first one occurs at the entrance. It explains the phenomenon commonly called the inlet-tube corrosion, which is often observed in pipelines. The second one takes place at a short distance from the edge of entrance, which explains how corrosion can cause a wavy appearance on metal surfaces.

Subject
Water, Piping, Fluxes, Correlation, Corrosion rate, Metal surfaces, Walls, Pipelines, Ferrous ions, Reynolds number, Hydrodynamics, Mass transfer, Mass transfer coefficient
Keywords:
Local Corrosion, Corrosion Rate, Flow Induced Corrosion, Hydrodynamic Effect
© 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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