Iron-Containing Coatings on Asbestos-Cement Pipes Exposed to Aggressive Water

摘要

Coatings containing iron were found on asbestos-cement pipes exposed to a range of water qualities from very aggressive to nonaggressive. Under aggressive water conditions iron coatings had a granular, porous structure that prevented asbestos fibers from being exposed on the surface of the pipes but did not necessarily prevent leaching of calcium from the interior of the pipe (several millimeters from the surface). A modified durometer showed promise as a hand-held instrument for the assessment of A/C pipe softening in the field. The numerical value of hardness given was related to the amount of calcium leached from the pipe but was not directly related to the amount of fiber exposed on the surface of the pipe.