Two fire water pumps (FWP) of Bombay Offshore failed after total running period of few hours. Detailed failure investigations were carried out on failed shaft sleeve and wear ring of fire water pump. As per specifications, the shaft sleeve should be made of Monel K-500 and impeller and wear ring of A-743 CD4MCu. Scanning electron microscopy and microstructural studies showed the presence of dendritic structure in sleeve material. The hardness value of sleeve material was found different from actual hardness of Monel K-500. Qualitative and quantitative elemental analyses of sleeve material were carried out using Energy Dispersive Spectroscope and Inductively Coupled Plasma Emission Spectrometer.

Galvanic corrosion studies between sleeve material and A-743-CD4MCu material indicated insignificant galvanic effect. Electrochemical polarization studies confirmed that sleeve material is behaving as cathodic in non-chlorinated and chlorinated solution. However, rate of corrosion was more in chlorinated sodium chloride solution showing that excess chlorination has accelerated the corrosion rate of sleeve material-Based on the various studies, it has been observed that failure of sleeve material was due to dendritic segregation and selective dissolution and corrosion was accelerated due to excess chlorination.

Subject
Wear, Water, Materials, Corrosion rate, Microstructure, Chlorination, Sodium chloride, Structures, Chlorine, Monel alloys, Hypochlorite, Hardness, Samples
Keywords:
Fire Water Pump, Shaft Sleeve Material, Monel K-500, Dendrites, Lack of Homogeneity, Selective Dissolution, Chlorination
© 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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