Leaching corrosion of asbestos cement pipes

Improving pipe failure predictions: Factors affecting pipe failure in drinking water networks

“…Storage is a specific issue for PVC, as exposure to ultraviolet light for long periods of time embrittles the material. Improper bedding conditions, as reported by Al-Adeeb and Matti (1984), cause higher failure rates in AC pipes due to bending stresses from inadequate support. Kirby (1981)…”

“…However, corrosion did occur in sulphate rich soils or where acidic ground water was present. Al-Adeeb and Matti, (1984) also reported leaching of free lime in pipes that conveyed very soft water. However, AC is a rigid and brittle material and less flexible than DI and steel (Mordak and Wheeler, 1988) so it is less resilient to ground movement.…”

“…This results in hole formation within the pipe matrix, eventually leading to a soft material where the cement no longer binds the asbestos (Gong et al, 2016). Lime leaching in pipes can also occur when conveying very soft water (pH >7 and a hardness of < mg/l of calcium and magnesium carbonate) which promotes lime leaching and eventually leads to pipe failure (Al-Adeeb and Matti, 1984). Sulphate attack occurs when sulphate in the surrounding groundwater reacts with the calcium hydroxide in the AC material to form calcium sulphate.…”

Prediction of Asbestos Cement Water Pipe Aging and Pipe Prioritization Using Monte Carlo Simulation

“…Asbestos cement pipes failures occur in two ways, circumferential failure due mechanical loading, and longitudinal failures which occur as a result of material corrosion [10].The longitudinal failures occur in 80% of burst field pipes [11]. Mechanical failure is generally a result of poor trench conditions and locating of the pipe (i.e.…”

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

“…Free lime (calcium hydroxide) leaches into the water conveyed by, or surrounding, an AC pipe over time through diffusion, resulting in decomposition of hydrated silicates, an increase in porosity and a loss of material strength 2,6 , although typically no apparent reduction in wall thickness is observed. Soft water with a low ion content, such as pure distilled water, can cause lime leaching and wall deterioration, while acidity can enhance the process 2 . Sulphates in the water and soil surrounding an AC pipe can react with calcium hydroxide to form calcium sulphate, which in turn can react with hydrated calcium aluminate to form calcium sulphoaluminate .…”