Process Optimisation of the Joining Phase in Heated Tool Welding of High-Wall-Thickness Polyethylene

Heated tool welding has been successfully used for decades to join semi-finished polyethylene products. Increasingly, large pipes with high wall thickness are being used for the expansion of infrastructure for sustainable energy supply. Although the widely established DVS guideline 2207-1 defines parameters for wall thicknesses of up to 130 mm, only theoretically extrapolated process times exist for higher wall thicknesses due to a lack of scientific studies. Practical experience confirms the necessity of investigating alternative process strategies. Therefore, the joining and cooling phases of the welding process were studied at Chemnitz University of Technology, resulting in an optimised process control approach. By correlating the joining time with crystallisation in the weld seam, significantly improved service lives were achieved in creep tensile tests.