Mains Condition Assessment by Echopulse, a Validation of Results

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

“…The dimensions of the AC pipe are taken from Australian Standard 1711-1975 for AC pressure pipes. 39 The modulus of elasticity of intact AC is 32 GPa as experimentally determined by Beuken et al 14 from AC pipe samples. The Poisson's ratio of AC is assumed to be 0.2.…”

“…The previous sub-sectional condition assessment gives the average wall condition of the sub-sections within a long pipe section bounded by two measurement points, which is a medium-resolution assessment technique when compared with the low-resolution acoustic-based average wall thickness estimation. 13,14 For significant deterioration with a short length, which are categorised as localised defects in this article, a different approach, namely, localised defect detection, is used for comprehensive analysis of the wave reflection and other known information. The localised defect detection complements the sub-sectional condition assessment by providing high-resolution information at specific locations.…”

“…For non-destructive direct inspection of the wall condition of AC pipes, currently there are two technologies available: georadar-based wall thickness measurement 12 and acoustic-based average wall thickness estimation 13 . The georadar technique can realise high-resolution in-line inspection for AC mains greater than 200 mm, but the cost is high and access to the interior of the main is required 14 . The acoustic average wall thickness estimation technique is non-invasive and non-destructive, but it is a low resolution technique because only the average wall thickness between two measurement points can be determined.…”

“…13 The georadar technique can realise high-resolution in-line inspection for AC mains greater than 200 mm, but the cost is high and access to the interior of the main is required. 14 The acoustic average wall thickness estimation technique is non-invasive and non-destructive, but it is a lowresolution technique because only the average wall thickness between two measurement points can be determined. The determined average wall thickness can be misleading if the tested pipe section has unregistered pipe replacements, material changes or class changes.…”