Internal Wall Condition Assessment for Water Pipelines Using Inverse Transient Analysis

A methodology for determining the wall condition of water pipelines, by using an inverse transient model to interpret the measured response of the pipeline to deliberately induced controlled transients is presented. Changes in pipe wall lining and thickness theoretically give rise to reflections in measured transient responses and these can be interpreted to assess pipeline wall condition. The results of field tests on a 750mm diameter pipeline, containing reflections from a damaged section of pipeline, are presented. A distribution of known damage (determined from CCTV camera footage) and inferred damage is characterised in terms of four categories of wall deterioration. This distribution of damage is then included in a transient model of the pipeline and the measured and predicted reflection response are found to compare favourably. The transient model is then combined with a Genetic Algorithm and inverse transient analysis is performed using transient data generated from a distribution of known, inferred and arbitrary damage. The inverse transient analysis relatively accurately predicts the pre-determined distribution of damage along the pipeline.