Heinlein, Sebastian; Imperial College; United Kingdom
Burch, S.F.; ESR Technology Ltd; United Kingdom
Cawley, P.; Imperial College London; United Kingdom
Heinlein, S.; Imperial College London; United Kingdom
Vogt, T.; Guided Ultrasonics Ltd; United Kingdom
Session: Guided Waves - Structural Health Monitoring
Time: 11:10 - 11:30
Guided wave permanently installed monitoring systems (PIMS) are potentially very attractive for ensuring the integrity of critical structures, particularly where access for frequent NDT is difficult, but their performance has not yet been satisfactorily validated. This paper presents the results of a blind trial of a guided wave PIMS system on an L shaped 8 inch diameter pipe section with an overall length of 10m, a 1.5D bend, and a total of three butt welds. Readings were taken at 30 minute intervals over a period of roughly 40 days while the pipe temperature was cycled between ambient temperature and 60°C, during which six simulated corrosion defects were introduced. The data was sent in batches to an evaluation team who had no knowledge of the defect locations or the schedule for their introduction; they reported on the data before being given the next batch. A new independent component analysis (ICA) scheme was used to process the measurement data and all the defects were successfully located with no false calls. It was found that the detection sensitivity was about a factor of 5 better than that typically obtained in one-off guided wave tests. Permanently installed guided wave monitoring systems are therefore a very promising technology for monitoring critical infrastructure.