How to Inspect HDPE Butt Fusion Welds High-density polyethylene (HPDE) pipe welding is different from traditional welding, and butt welding of HDPE is even more so. It requires specialised equipment like an HDPE welding machine, which comes in different types, such as hydraulic, manual, and automatic. Butt welding presents challenges like decreased structural strength and other flaws, making it necessary to inspect welds to ensure optimum quality. There are various ways to do this, including non-destructive testing (NDT) technologies like ultrasound. That said, HDPE material has some attributes that can make ultrasonic scans challenging. So, it is crucial to have a reliable inspection strategy that includes several testing techniques to find flaws in welds without compromising the strength of the results. What flaws can occur during butt fusion welding? Flaws can occur while using an HDPE welding machine due to inaccurate temperature, lack of weld force or pressure, improper surface cleaning, existing external inclusions in the material, insufficient cooling times, and other factors. These incidents could cause problems like cold fusion or a partial bond, cracks, and porosity, requiring proper and thorough identification. Ways to inspect weld quality HDPE has attenuative properties that require inspection with minimal frequencies, unlike when inspecting carbon steel. With this in mind, it’s advisable to use inspection methods using pulse-echo, tandem PAUT, and TOFD (time of flight diffraction). Combining PAUT with TOFD delivers volumetric inspection capabilities with optimum flaw detection sensitivity. It achieves the following:
Focus on weld joints and heat-affected zones to identify flaws Find any inclusions, voids, pores, or slags Gauge the fusion weld bond strength Reduce the effect of thickness irregularities or variation