Submerged Arc Welding SAW

Longitudinal submerged arc welding (SAW) in FZC 11 Okomvri A.D. is used as a standard welding process for manufacturing steel pipes with a large diameter. These steel pipes are mainly used in national linepipes for transport of  oil and gas, and transportation of drinking water, waste-water and other liquid fluids.

It also find widespread use as elements of steel structures, machine building and others.

Longitudinal welding process (SAWL) with additional material in the form of steel wire, with defined diameter and quality depending on the basic material, protected by the suitable flux, derived from internal and external side provides greater safety compared with the spiral welding process (SAWH), because of significantly less length of weld.  This is important for transport of high working gas pressures, where exist a need for increased level of quality control and minimal risk.

The production process consists of several related entities:

  • Chemical processing of hot rolled steel sheets – decapping and protecting.
  • Cutting of the longitudinal natural edges of hot rolled sheet.
  • Cold forming – Bending.
  • Longitudinal and transverse automatic submerged arc welding (SAW) passed in two, internal and external side of the pipes
  • Calibrating the ends of the pipes.
  • Processing ends for the assembly weld.
  • Ultrasound control along the whole length of the longitudinal weld.
  • Hydro-static testing.
  • Final ultrasound control along the whole length of longitudinal and transverse weld.
  • Radio-graphic examination of welded joints at the ends of the pipe and the joints of transverse and longitudinal weld.
  • Marking.