Inorganic zinc (IOZ) silicate coating was previously applied to partially fabricated low alloy, 2-1/4 Cr-1MoV, high temperature, hydrogen, reactor vessels for long-term storage corrosion protection prior to final welding and post weld heat treatment (PWHT) at 690-720°C (1274-1328°F). The need for complete coating removal to mitigate the known embrittlement and weld cracking that can occur after welding and PWHT led to the development of a novel, environmentally-friendly method to remove IOZ to trace levels below 1 ppm. Typical blasting and etching procedures were unable to effectively remove the coating.

The success of this IOZ removal method is the first-known achievement of IOZ removal to trace levels below 1 ppm. This method can be utilized in restoration projects of bridges and structural steel where abrasive blasting is not practical or environmentally unsafe.

This paper discusses the chemical mechanism of this new coating remover, method of application and testing, the validation program utilizing X-Ray fluorescence (XRF) analyzer energy dispersive X-ray spectroscopy (EDX) calibration, and effective field implementation.

Subject
Coating removal, Zinc rich coatings, Energy dispersive X-ray spectroscopy, Materials, Metal surfaces, Welding, Surface analysis, Zinc silicates, Steel, Zinc, Elements, Inorganic zinc rich coatings, Cleaning
© 2015 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).
2015
Association for Materials Protection and Performance (AMPP)
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