INDRO filter welder-filter cartridge middle seam welding machine is special for middle seam of pleated filter cartridges which are made of polypropylene, PES, fiberglass, PTFE, nylon and other non-woven filter media. Welding example: 68-69mm diameter pleated filter cartridge, 56mm/60mm diameter pleated filter cartridges, 152mm 165mm, 160mm diameter high flow pleated filter cartridges.