Corrosion under insulation (CUI) is a costly and complex problem for industry to contend with successfully. This paper describes a suite of accelerated laboratory tests undertaken in part to evaluate some of the claims made for engineered coatings touted to possess high heat resistance to 400°C and simultaneous anticorrosion properties.

Thermal spray aluminum (TSA) was used as the benchmark to assess the coating performance of three liquid-applied coatings in cyclic temperature and corrosive microenvironments. All four coatings were applied to carbon steel pipe. The liquid-applied coatings consisted of a titanium modified inorganic copolymer (TMIC), and two materials based upon modified silicone technology. The coated and insulated pipe was heated to temperatures from 90°C to 445°C.

Investigations were carried out (a) to evaluate the resistance of the coatings to CUI Cyclic conditions at 95°C to 445°C, followed by cyclic immersion in a salt solution and heating at 200°C, (b) on a repair patch of the TMIC on TSA, (c) to compare and contrast the performance of the coatings using EIS (Electrochemical Impedance Spectroscopy), and (d) using optical microscopy and SEM (scanning electron microscopy) to investigate the porosity of each coating system as a function of temperature at 100°C, 200°C, 300°C, and 400°C.

In light of select case histories and the present accelerated laboratory studies, the importance of the CIA will be manifested in the undercover realm of CUI - not as in the case of the Central Intelligence Agency, but rather in the realm of “Coatings in Action”.

Subject
Scanning electron microscopy, Test methods, Coating performance, Coatings, Piping, Insulation, Aluminum, Porosity, Heat, Corrosion under insulation, Immersion, Cracking, Barrier coatings
© 2012 Association for Materials Protection and Performance (AMPP). All rights reserved. This work is protected by both domestic and international copyright laws. 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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