Non-destructively testing plastic pipe welds
PE is lightweight, has long predicted service life and leakage-resistant — all of which decrease installation and maintenance costs of piping, while reducing environmental hazards. Until now, testing the joints in PE pipes required weld removal for mechanical testing or visual inspection. The EU-funded project TESTPEP developed an automated phased-array ultrasonic non-destructive evaluation (NDE) system. This enables the volumetric analysis of welds in PE pipes, either during production or retrospectively. The team successfully optimised all the main system components and characterised ultrasound propagation for both medium density and high density PE pipe materials. Procedures were then developed to insert planar flaws and particulate contamination into both butt fusion and electrofusion welds. Following this, numerous welds with variable flaws were manufactured to develop inspection procedures and flaw acceptance criteria, based on both short-term and long-term mechanical performance. Researchers designed and manufactured novel phased-array probes and different probe holders and attachment mechanisms for the modular scanning system. These are capable of inspecting welds in PE pipes of diameters ranging from 180 to 710 millimetres. Automated software analyses the inspection data, generating a map of the weld and comparing results with acceptance criteria. The complete prototype phased array ultrasonic inspection system has been assessed in the laboratory, during manufacturing and in the field. In the assessment trials, the system successfully detected all major flaw types of interest to the European plastics pipes industry. TESTPEPs ultrasound-based NDE technology for welds in plastic piping fills a critical industry need for standardised flaw detection and acceptance criteria. Information about the project including brochures, magazine articles, conference papers and videos can be found in over 25 publications on the project’s website. Commercialisation will reduce leaks, disruptions due to repairs and the environmental risks of catastrophic failures. Increasing confidence in the use of plastic piping will also enhance the competitive position of plastics’ manufacturers.
Keywords
Polyethylene, non-destructive testing, pipe, weld, phased-array, ultrasonic, volumetric analysis, flaw acceptance criteria, probe, prototype
