Chapter 7 - TIG and MIG welding developments for fabrication of plant for the chemical, petrochemical and offshore oil and gas industries

Abstract

From the contents of this chapter, it is appreciated that effective automatic TIG welding processes have been developed, offering increased rates of weld deposition, to compare favorably with MIG procedures. In turn, piping requirements have involved smaller diameters and thicknesses for reaction tubes and coils, so that any cost differences between welding processes have been reduced relative to the total product value. For fixed position welds in shop and on site (field) orbital pulsed TIG, automatic welding has become established especially for good control of root runs and the uniformity of the penetration beads. Development of the Synergic MIG process with a stable pulsed arc and low spatter propensity has increased the scope for the MIG high deposition rate technique now used for relatively heavy section welds, such as vessel branch connections, and for surface overlaying high strength steels with corrosion-resistant weld metal.