Using fluid transients to detect anomalies in pipe systems

Graeme Dandy | Holger Maier | Angus Simpson | Martin Lambert
Peng Bi | David Jones | Andrew Metcalfe

There are many resources that need to be delivered within a city, one of these is water. Water is delivered conventionally via buried pipelines. Over time pipelines degrade, as they are being attached from within by the fluids they transport, and from outside by soil and ground water processes. Traditionally, pipelines have to be physically inspected for fault determination resulting in significant costs. New condition assessment techniques can result in large cost reductions by probing into pipelines without digging them up. One of these techniques is using non-invasive fluid transients to detect pipe anomalies.

Fluid transients are small pressure waves that are injected into the system, with a reflection that is received back and interpreted to reflect actual pipe conditions. The behaviour of fluid transients reflect the internal wall conditions of the pipeline. When an anomaly is detected, the reflection from it will be apparent on a measured trace and the location can be found from the timing of the reflection. These low amplitude waves are effective as the signals are externally generated, fast (>1000 m/s) and can travel over large distances (> 1 km).

Most progress to date has been made from determining the pipe interior, but other research into looking for air pockets that effect the hydraulic conductivity of the pipe, tuberculation or blockages, finding closed or malfunctioning valves, are all prospects of this technique. There are many challenges in refining this technology - to synchronise waves accurately over large distances, how to get pressure waves into the system, modelling of the observed transient, and most importantly to infer the true nature of the condition of the pipe. One future application will be to look for cross connections between recycled and existing water pipes as a greater proportion of water is recycled in the future, in particular for places like Adelaide.

Objectives
• Develop new methods of condition assessment using fluid transients to detect
- changes in wall condition
- air pockets in pipes
- blockages
• To validate these approaches in the laboratory and under field conditions
• To transfer benefits of the research to industry and the community