A new NDT inspection technology for polyethylene electrofusion pipe joints is being developed as a simple-to-use, patented, cost-effective and highly accurate tool based on A-scan ultrasonic technology. As the wave form output from an A-scan contains a significant amount of information about the substrate through which the sound passes, the key to this methodology is the novel assessment approach for analysis of the sound waves. Originally developed by impact solutions for assessing large diameter fittings in the UK water industry, the technology is currently being adapted by JANA and Impact Solutions for use on smaller diameter gas distribution piping electrofusion fittings.

A blind Proof of Concept trial was conducted to assess the technology’s detection capabilities. Multiple member companies from NYSEARCH provided coupling and tapping tee electrofusion joints with unidentified defects for assessment. Twenty-six samples with 28 joints were prepared using different materials, sizes and manufacturers for the pipe and fittings. NDT assessments were conducted on each joint and spectral anomalies were identified by specific location. Each joint was assessed based on green (no anomalies detected), yellow (some anomalies detected) and red (significant anomalies identified) criteria.

Overall, the NDT technology achieved a 92% correlation rate between the observed anomalies and joint quality. There were 22 joints of poor quality and 6 joints of good quality in the study. The technology successfully detected anomalies in all joints of poor quality (22/22). The technology successfully detected no anomalies in the fusion zone of 4 of the good quality joints. The NDT detected anomalies in 2 of the good quality joints.

Two joints in the study that were intended to be prepared as poor quality joints were determined to be of good quality through the NDT assessment and this was verified by destructive testing. Two joints that were intended to be good quality joints were determined to be of poor quality through the NDT assessment and this was verified by destructive testing.