Mats Bergman, Karin Jacobson
Papers # 2016 Berlin
The Swedish Water & Wastewater Association (SWWA) has funded a R&D project to investigate different methods suitable for installation inspection of PE joints in field. Methods like phased array ultrasonic testing (PAUT), microwave technology and digital radiography were studied. Digital radiography shows promising results in finding defects and imperfections as pores, oblique-angled, toe-in and ovality, incorrect insertion and dirt and impurities. It has also been successfully used to investigate the changes in the weld during a welding cycle.
Our conclusion is that digital radiography should be considered as part of a prescribed standard for installation inspection of electrofusion PE joints and that it is a powerful tool to be used for research and development into improving the welding performance.
The water utility sector faces major challenges as large sections of the drinking water network must be renovated, and new installations of water mains are made on a large scale in many cities. Polyethylene (PE) is the leading material for new installation of drinking water pipes in Sweden and also for sewer systems and gas applications. The material is recognized by the market as a flexible, light weight and cost effective solution. However, there have been a fairly large amount of failures of electrofusion joints after only a few years in service. Failure investigations have shown that in most cases the installation of the joint had not been performed correctly.
This has large economic consequences and also, in the case of gas piping, safety concerns. Studies in Sweden show that the total average cost for fixing a leak a water supply system is about 50 kEUR. So there is clearly a need to improve the quality of the installation. An integral part of this is the quality control at the installation.
The Swedish Water & Wastewater Association (SWWA) has funded a R&D project to investigate different methods suitable for installation inspection of PE joints in field. Methods like phased array ultrasonic testing (PAUT), microwave technology and digital radiography were studied. Digital radiography shows promising results in finding defects and imperfections as pores, oblique-angled, toe-in and ovality, incorrect insertion and dirt and impurities. It has also been successfully used to investigate the changes in the weld during a welding cycle.
Our conclusion is that digital radiography should be considered as part of a prescribed standard for installation inspection of electrofusion PE joints and that it is a powerful tool to be used for research and development into improving the welding performance. The presentation will give the background of the project, an overview of digital radiography technology and the result as images of different kind of defects.
