Polyphosphates are effective inhibitors to control a variety of problems in potable water distribution systems. They are produced from the condensation reaction between phosphoric acid and a base. The Na2O:P2O5 ratio determines the chain length. Polyphosphates are cathodic inhibitors and provide good carbon steel corrosion control. The addition of zinc is synergistic, further reducing corrosion and accelerating protective film formation. Polyphosphates are excellent threshold calcium carbonate inhibitors. They also are capable of stabilizing dissolved iron and manganese and preventing "red" and "black" waters. During pigging operations, zinc polyphosphate provides steel protection by preventing flash rusting and disperses corrosion by-products.

Subject
Water, Materials, Ions, Metal surfaces, Calcium carbonate, Carbonate scales, Calcium, Manganese, Ion concentrations, Phosphates, Corrosion inhibitors, Deposit corrosion, Zinc
Keywords:
polyphosphate, corrosion, potable water, scale, iron stabilization, manganese stabilization
© 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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