EFW namely the abbreviation of the first letter for electric welding electric fusion welding. Submerged arc welding (SAW) pipe is a kind of EFW pipe, containing the LSAW steel pipe and SSAW steel pipe. EFW is a kind of technology process - heating the metal to combine, which is caused by the interaction between the one or a few consumable electrode and workpiece, and the arc shall fully melt the metal and the filler material, do not need to pressure, and filler metal part all comes from the electrode.

ERW namely first letter abbreviation of electric resistance welding. There are significant differences between the ERW pipe and EFW pipe. It is adopting the form of the pressure welding with the no-filling metal, and no other ingredients in the welding seam. In the action of skin effect and proximity effect of the high frequency current, make the edge instant heating to welding temperature, and form welding seam of the organization by squeezing roller extrusion forging.

High quality steel pipe requires an on-line or off-line weld heat treatment, to get the welding structure refined. And high quality ERW pipe welds can reach the same level of toughness with the base metal, which the EFW process can not achieve.