th Middle East Nondestructive Testing Conference , 7-10 October 2012 , Kingdom of Bahrain Phased Array Ultrasonic Testing of Welded Joints in Plastic ( PE ) Pipes
A reliable Non-Destructive Testing approach is required for the inspection of polyethylene (PE) butt fusion joints in various material grades and pipe sizes. The nature of butt fusion joints is that the fusion zone is relatively small and the inspection solutions are often restricted by the existence of an external weld bead. This weld bead restricts the probe placement and the probe needs to be positioned in a non-optimal position for the weld inspection. The PE material grades have low velocity and high frequency dependent attenuation, which will complicate the inspection of thicker pipes. In this paper, phased array ultrasonic techniques are presented and their capabilities are evaluated. The techniques utilise customised water wedges to be able to generate forward angle beams to cover the weld within the PE pipe. Techniques have been developed for pipes with outer diameters between 220-710mm and thicknesses between 14-45mm. Probe and wedge parameters have been optimised for this range of pipes. The capability of detecting circular defects with diameters between 1.5-8mm on pipes with an outer diameter between 220-710mm using a phased array ultrasonic inspection solution, and the challenges overcome when working with this type of material, are presented.
Effect of joint contamination on the quality of butt-fused HDPE pipe joints
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Fast weld field trials – high productivity butt fusion jointing of polyethylene pipes
This research work took place up to and during 1997 and the results hereafter are from that research. However, since then there has been additional research work. For the purposes of this paper the principles remain fundamentally consistent; however, the reader should recognise the concept has been refined since the paper was initially published. The butt fusion procedures used in the UK water and gas industries, which determine the total time taken to complete a successful joint, have remained largely unchanged since their harmonisation in 1990. The parameters evolved to suit manually operated butt fusion machines and reflected the fact that the minimum achievable heater plate removal time, for up to 250 mm diameter, was between 6 and 8 s, during which the operator had to manually operate a hand pump to remove the heater. With standardisation of automatic butt fusion, and typical heater plate removal times of 2 s, the potential exists to reduce considerably the on site jointing time and thus enable substantial financial savings. Trials to date have been exclusive to second generation medium density polyethylene PE80, due to its known tolerance to variances in jointing parameters, which can occur with manual machines working in site conditions. Further work to determine the fast weld parameters of third generation high density polyethylene PE100 is planned for the future.