Abstract
Field experience with asbestos-cement (A/C) water distribution pipe used in potable water service for conveying corrosive (aggressive) waters is reported. Forty-five samples of A/C pipe from geographically diverse areas and of varying ages were analyzed for signs of corrosive water attack and loss of structural integrity. All but 3 of the samples tested for crush strength exceeded the requirements for new pipe. Corrosion penetration was minimal or absent in most cases, particularly for pipe conveying low to moderately aggressive water. The long term performance of factory applied coatings was found to be excellent. Iron based inorganic coatings, apparently from the corrosion of metallic system components, were deposited in situ on some of the pipe samples but the protection thereby provided against aggressive attack was indeterminant. Data from other industry and EPA studies show that metal salt based corrosion inhibitors added to the water can, under certain conditions, retard aggressive water attack on A/C pipe provided the inhibitor is added properly and continuously to the water stream.
Composition, manufacture and testing of A/C pipe are also discussed. Data on the variability of crush and hydrotest results are presented. Conclusions regarding the long term performance of A/C pipe and the efficacy and need for protective coatings are given.
