The process of welding the pipe with the front-end profiled coupler (Trans Quadro is a manufacturer of bends, hole plugs, reductions, T-pipes and sleeves) can be divided into two phases: the first one comprising the pipe and coupler preparation and the second one being the welding process itself. The pipe and the profiled coupler with planed coupling surfaces are properly aligned and pressed against the heating plate of the welding equipment, what causes formation of fashes (plastic zones). After proper heating of the fashes the tips of the parts being connected have suitable temperature and store suitable quantity of heat. Then the heating plate is removed and the tips are depressed one against another and welded. The process is controlled by maintaining proper pressure in hydraulic cylinders of the actuators. The connecting (welding) phase is subsequently followed by the cooling phase.