Corrosion reached epidemic proportions in the City of Long Beach (CA) when in 1962 a 50% blend of treated well water and Colorado river water was introduced into the distribution system.

Caustic soda, lime, soda ash, sodium silicate, sodium hexametaphosphate and a zinc fortified metaphosphate were applied individually and in combination to tha water as a solution to the problem from 1962–67 but these materials were ineffective and actually intensified the corrosive attack.

In 1967, two zinc-based corrosion inhibitor formulations were developed, one with sodium metasilicate, produced a 55-85% reduction in steel corrosion while the second with phosphoric acid, resulted in a 95% reduction in steel corrosion.

The zinc metasilicate method was expensive since a continuous dosage of 3 ppm zinc and 30 ppm metasilicate was necessary accompanied with a water pH adjustment to 8.4. The zinc orthophosphate technique of corrosion inhibition in contrast, required only an initial 3 ppm zinc passivation dosage which was reduced to a continuous 1 ppm maintenance dosage.

Subject
Water, Materials, Orthophosphate, Lime, Rivers, Bicarbonates, Plumbing, Dosages, Acidity, Sodium, Corrosion inhibitors, Steel, Zinc
© 1984 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).
1984
Association for Materials Protection and Performance (AMPP)
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