Condition Assessment Methods for AC Pipe and Current Practices

Abstract

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Field study on non-invasive and non-destructive condition assessment for asbestos cement pipelines by time-domain fluid transient analysis

“…Substituting equation (7) into equation (3) results in the following expression for the dimensionless reflected head perturbation…”

“…The three possible explanations for the anomaly (deteriorated AC, plastic replacement or air pocket) are checked in sequence. If the anomaly is a deteriorated AC section, the relative change in wall thickness is determined as e rc = À 0:723 using equation (7) or (8). Substituting the determined e rc into equation (5) and using the determined average effective AC wall thickness of sub-section S5 (15.8 mm) for e 0 , the effective AC wall thickness for the assumed deteriorated AC short section is determined as e eff = 4:4 mm, which indicates a reduction of 12.9 mm or 75% from the original condition.…”

“…However, due to the unique material properties and deterioration mechanisms of AC pipes, the number of techniques available for assessing their condition is limited compared to those available for ferrous pipes. Environmental assessment techniques 7 , such as water quality testing and soil testing, are useful for assessing the possibility of deterioration but are indirect and cannot yield information as to the actual present condition of a pipeline.…”

“…1 However, due to the unique material properties and deterioration mechanisms of AC pipes, the number of techniques available for assessing their condition is limited compared to those available for ferrous pipes. Environmental assessment techniques, 7 such as water quality testing and soil testing, are useful for assessing the possibility of deterioration but are indirect and cannot yield information as to the actual present condition of a pipeline. Selective sampling test techniques, such as mechanical testing, 6 phenolphthalein testing, 8 hardness testing 9,10 and scanning electron microscopy with energy-dispersive X-ray (SEM/EDX) analysis, 11 require the removal of short sections, or coupons, from an AC pipe, which is a destructive and expensive process.…”