High frequency resistance welded steel pipe (erw steel pipe) has the following characteristics:
(1) High frequency resistance welding filler metal is pressureless welding.
(2) High frequency resistance welding has the advantages of fast welding speed and high production efficiency. Because of the high energy concentration in the welding zone and the fast heating speed, the welding speed is fast. For example, 426 units were imported from China, with the highest welding speed of 45m/min and the lowest welding speed of 15m/min.
(3) HAZ. Because of the high concentration of energy welding, fast heating speed, fast welding speed, and strong self-cooling effect of workpiece, the heat affected zone.
(4) Requirements of high welding production technology and management level. High frequency welding is resistance welding in continuous production line. It has fast welding speed, high production efficiency and many factors affecting welding process. It is necessary to have a high level of technology and management to make the coordination of more welding elements in the whole production line stable to obtain high quality welded steel pipe.