Polyethylene (PE) piping has found wide use in chemical processing, water transportation, and gas distribution applications because it is lightweight, corrosion resistant, and easy to join in the field. Common joining methods include electrofusion and butt fusion. The mechanical integrity of joints is highly dependent upon the installation parameters; including cleanliness of the pipe face, pipe end alignment, pressure applied during fusion, and temperature of the ends during fusion. Typical installation defects can include foreign debris in the weld, e.g. grass, grease, dirt; weak welds; and debonds. Many times, visual inspection of the weld will not detect these defects, and the cost of repairing a joint after it is placed in service is exorbitant. This has generated interest in developing a nondestructive evaluation (NDE) method that can detect defects during installation. This paper reviews several NDE methods that have been applied to inspection of PE butt welds. Specially designed NDE equipment is also discussed. This overview paper addresses NDE techniques for inspection of butt welds in PE piping during installation. Several NDE approaches are evaluated for applicability to this inspection. Factors evaluated include time duration of test and ability to detect various defects.
Keywords: polyethylene pipes, nondestructive testing, radiography, ultrasonics, butt fusion