erw

Electric Resistance Welding (ERW) is a welding process that joins metal parts by heating them with electric current flowing through the workpieces. In the pipe and tube industry, ERW typically forms a sheet or strip into a tube and then creates a longitudinal seam by passing a high current through the abutting edges under pressure, melting and fusing them along the joint. The result is a welded pipe or tube with a continuous seam.

There are two common forms: high-frequency ERW (HF-ERW), which uses induction heating to localize heat at the edges, and conventional HF or medium-frequency methods combined with roll forming to bring the edges together. After forming, the seam is often reinforced with rollers and can be trimmed or flattened. The weld may be inspected by non-destructive testing, such as ultrasonic testing or radiography, to verify seam integrity. HF-ERW is widely used for steel pipes and tubes, particularly in smaller diameters and thinner walls.

ERW pipes are manufactured in a range of diameters and wall thicknesses and are widely used for water supply and distribution, gas lines, construction tubing, and electrical conduit. They are generally more cost-effective than seamless pipes for smaller diameters and thinner walls, though they may be less suitable for very thick-walled or high-tensile applications.

Quality and standards: ERW products conform to various national and international standards from organizations such as ASTM, ISO, and EN. Production typically includes testing and inspection to verify weld integrity, sometimes involving hydrostatic testing and nondestructive testing.