Field evaluation of in-service buried pipeline using robust instrumentation

Abstract

In-depth field instrumentation was undertaken on a section of a large diameter (660 mm) cast iron water pipe in Sydney, Australia to monitor the performance of a field pipeline under internal and external loads. This paper elaborates the instrumentation details and procedures adopted to capture various infield data to support the condition assessment of buried ageing pipelines under operational conditions including internal water pressure and external traffic loads. The adopted instrumentation realistically captured pipe strain, pipe joint displacement and rotation, soil pressure, temperature and moisture content. The results are discussed to evaluate the efficiency of the instrumentation for real-time monitoring which facilitates the understanding of the behaviour of a field pipeline. The pipe strains measured under various traffic conditions provide useful estimations for the evaluation of the condition of ageing pipelines. Fairly uniform strains were detected under internal water pressure loadings which showed a considerably larger impact on pipe performance than that due to other influential factors. The soil vertical and lateral pressures measured at various locations around the pipe revealed the relative magnitudes of ground stresses, facilitating new designs and the failure assessment of in-service buried pipelines. Soil moisture and temperature data showed variations directly related to atmospheric conditions. The robust field instrumentation adopted in this study is useful for the accurate monitoring of in-service pipes which may be highly vulnerable to catastrophic failure due to ageing-induced corrosion and severe operational loads.