Extrusion welding is a method for joining of thermoplastic materials utilizing a filter material, heat and pressure. The process finds its main applications in the field of customer thermoplastic fabrication and geomembrane liner installations (detail work, repairs). In their infancy stages, extrusion welders were comparatively large machines mounted on wheels, today's technology permits hand held models of different sizes with output capacities of up to 4.5 kg/hr (approx. 10 lbs/hr). Although the application of extrusion welders has seen a considerable expansion in the past ten years, very little documentation has been established.