Tue, 16 January, 2024
Polyethylene (PE) pipes are used widely for gas and fluid distribution in numerous industry sectors. Traditionally, quality assurance (QA) of welded joints in PE pipes is achieved during installation by recording the welding parameters used, together with a visual inspection of the welded joint and a short-term hydrostatic pressure test, supplemented by destructive testing of sample weld specimens cut from the welded joints.
The Polytest inspection system, developed by TWI’s NDT Group, enhances this QA process for butt fusion (BF) and electrofusion (EF) welds, through full volumetric inspection of the welded joint, using Phased Array Ultrasonic Testing (PAUT).
PolyTest comprises a series of wheeled chain-links mounted on to the outside of a pipe, positioned adjacent to the weld to be inspected and a PAUT unit. The chain-link system rotates the attached PAUT transducer around the circumference of the pipe, enabling a full volumetric examination of the welded joint. It is compatible with pipe diameters in the range 90mm - 1,000mm and pipe wall thicknesses between 8mm - 70mm.
The Polytest portable scanner can be used effectively in manufacturing environments, or on-site (both above ground or in-trench) without taking the pipe under inspection out of service. Polytest complies with the requirements of ASTM E3044: Standard Practice for Ultrasonic testing of Polyethene Butt Fusion Joints, ASME Boiler & Pressure Vessel Code (BPVC) Section III and Mandatory Appendix XXVI.
TWI’s NDT Group has over 7-years’ experience of providing Polytest on-site inspection services on water and gas pipelines. Our inspection personnel are certified to ISO/9712 Level 2 for phased array UT inspection.
Figure 1. Inspection of a butt fusion (BF) joint, with the ultrasonic beam focussed at the BF weld centreline
Figure 2. Inspection of an electrofusion joint, with the ultrasonic beam focussed at the EF fitting/pipe interface
The following web links provide further information on the Polytest system:
Email the ‘Contact Us’ address below, to get in touch with the NDT team for help with your inspection needs.