Hot wedge fusion welding of HDPE geomembranes

Double track fusion welding offers more control, produces more consistent welds and is easier to nondestructively test than other types of welding system. However, as with other types of welding, there are a number of parameters which need to be understood and controlled in order to make consistently good welds. Heat, pressure and speed must be properly set, taking into consideration the resin being welded, the thickness of the sheet and environmental conditions.

Speed, heat and pressure must be controlled and their effect on weld quality understood. The ‘welding window’ for these variables has distinct boundaries. A test weld which exhibits melting, ‘squeeze-out’ and peels without breaking the liner may not need more pressure or heat. Tests show that for some bonds which peel apart, reducing the heat and/or pressure may be the correct action in order to obtain a film tearing bond (FTB).