TWI has unveiled a new inspection system that can reliably detect flaws in electrofusion and butt fusion joints in polyethylene (PE) pipes.
The latest in a line of innovations, PolyTestT extends TWI's expertise in ultrasonic testing to a new application. The system enables onsite inspection of both electrofusion and butt fusion joints in PE pipes, verified on sizes ranging from 90-710mm in outer diameter, with wall thickness ranging from 8-65mm.
PolyTest is a fully portable system that uses phased array ultrasonic testing techniques to identify flaws in welded joints caused by factors such as cold fusion, contaminants and pipe under-penetration.
The flexible, modular system consists of wheeled chain links that are mounted on the outside of the pipe adjacent to the weld to be inspected. The chain link system is rotated around the circumference of the weld and enables the attached transducer to complete a full volumetric examination.
TWI has developed bespoke membrane water wedges that house the transducer for PolyTest, both for electrofusion and butt fusion joints. The wedges are optimised to minimise electronic steering by the transducer elements, and the membranes are made of a flexible material that contains the water and adapts to the shape of the surface they are in contact with. The system provides full coverage of the weld zone while requiring no water supply.
Thorough tests, carried out on more than 200 welded pipe joints with inserted artificial flaws, have validated the system's inspection capabilities in joints with wall thickness up to 65mm and, with adaptation, even thicker pipes can be inspected. Extensive testing has also led to TWI determining acceptance criteria and critical flaw sizes for a wide range of welding processes and material combinations.
PolyTest produces immediate results and provides a permanent record. It conforms to the requirements of EN 13100-3 and relevant forthcoming ASME code, and allows operators to have increased confidence in the integrity of their PE welded joints.
The system is available for PE pipes in all industry sectors, including gas, water and nuclear, and satisfies regulatory requirements specifying that welded joints must be volumetrically inspected.
For more information about PolyTest please contact us.