Polyethylene pipe is commonly used for water and gas pipe transmission lines. One of the standard methods of joining these is by electrofusion couplings. These consist of a wire inside a coupler that is heated to melt and join the plastic. Flaws in the joining process can occur because of reduced heat in the wires, inaccurate cutting of the joints before assembly or poor insertion into the coupler, lack of fusion and contamination of the surfaces. Thermography and ultrasonics as NDT techniques are being tested for flaw detection, and mechanical testing to establish the flaw sizes of relevance are included in an EC CRAFT Project "Polytec Systems". This paper describes the experimental work in thermography as a method of monitoring the quality of electrofusion joints, and proposes a site method for future trials in the project.
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