Ultrasonic phased array inspection of electrofusion joints in polyethylene pipes

The electrofusion technique for joining polyethylene pipe is one of the common joining methods used in the water and gas industries for distribution pipes. Common problems in manufacture of these joints are contamination, lack of fusion, lack of penetration and insufficient heat applied to the weld resulting in a sticking or weak bond. The latter flaws can result in a joint that, although apparently fused, does not have the same mechanical properties as a properly prepared joint. The phased array technique has been specifically designed to provide a rapid inspection method for field application and this paper presents an ultrasonic technique for detecting and monitoring flaws in the weld. The results of the extensive laboratory experiments and the field application of the prototype system are presented.