The Pipeline Innovations Ltd Pathfinder is a full specification foam bodied geometry inspection tool used for proving the pipe bore on difficult to pig pipelines. The unique sensing technology and the simplified design allows the Pathfinder to operate in pipelines unsuitable for standard metal bodied cleaning, gauging and ILI pigs.

This paper presents the details of the Pathfinder inspection of the 8” x 63km gas pipeline located in a remote province in Northwest China. The pipeline supplies gas to urban areas and has a highly variable flow rate over each 24hr period. Since construction in 2011, 17 foam pigs and one metal bodied pig had been run through the line. The foam pigs sustained damaged and the metal body pig became stuck. After cutting out the pig, the pipeline operator, PetroChina, concerned that there may be additional large anomalies and excessive debris in the line, requested a full geometric Pathfinder survey to prove the line for pigging prior to progressive cleaning campaign.

Pathfinder was run through the line. Despite the highly variable flow rate, it collected good quality data, detecting and measuring 2327 bends, 37 internal diameter changes 4 large geometric anomalies and a partially closed valve. It also confirmed that there was no significant debris in the line. AGMs were used for tracking and providing distance reference points to locate anomalies. Verification digs were carried out on the four large anomalies with better than +/-1m location accuracy. One anomaly was located under a concrete pad on a steep rocky hillside. After remedial action to remove the obstructions, the client was able to confidently introduce hard bodied pigs to clean the line and progress to ILI inspection.