ERW is the abbreviation of electric resistance welding.
The welding method of ERW pipe and submerged arc welded pipe is significantly different. The pressure welding method without filler metal is adopted. The weld is not filled with other components, and the skin effect and the proximity effect of the high frequency current are used to instantaneously heat the edge of the plate. At the soldering temperature, the weld of the forged structure is extruded by a squeeze roll. High-quality steel pipes require heat treatment on the weld line or off-line to refine the microstructure of the weld zone. The weld of the high-quality ERW welded pipe can reach the same level of toughness as the base metal, which cannot be achieved by the submerged arc welding process.
EFW is the abbreviation of electric fusion welding.
One of submerged arc welding (SAW)-electric welding (EFW) is a process in which metal is heated by one or several consumable electrodes and a workpiece to heat the metal, and the arc is used to make the metal and fill. The material is fully melted and does not require pressurization. The part of the filling metal is all from the electrode. Melt Gas Shielded Welding (GMAW)-A type of electrofusion welding (EFW) that is similar to submerged arc welding, but its protection comes from inert gases and works better.
Spiral welding - this is also a type of submerged arc welding with a spiral weld.