For conventional oil pipeline welding, the quality is difficult to control and difficult to achieve the required welding slag are not allowed inside, however, more effective and widely used welding backing is made, manual arc welding method to cover up. In this way a clear arc, welding operation is simple, less prone pores, slag, incomplete penetration and other weld defects after, meanwhile, due to the small line capacity, so a small heat-affected zone, small deformation and cracking tendency.

Tungsten inert gas welding abbreviation TIG (Tungsten Inert Gas Weiding) welding. It is under the protection of inert gas, the use of tungsten arc generated by the electrode and the workpiece base material and the hot melt filler wire (filler wire if used) is a welding method. Continuous welding shielding gas ejected from the nozzle of the torch, the arc is formed around the protective layer is isolated from the air gas, to prevent a very harmful impact on the tungsten heat affected zone surrounding the weld pool, allowing for high quality welds.

TIG welding advantages:

1) TIG welding can weld metal and more, argon welding area can be effectively isolated from the surrounding air, it does not dissolve the metal, and the metal does not react. TIG welding process, arc welding as well as automatic scavenging surface oxide film. Therefore, the success of other methods of welding easily oxidized easily welded, nitriding, chemical reactivity and strong non-ferrous metals, stainless steel and various alloys.

2) protective effect, high weld quality. Ar is one of the most stable and inert gas which does not react with the metal reaction, soluble in the liquid metal does not generate pores, so it is excellent protection performance. Welding process is basically a simple metal melting and crystallization process, and therefore a high weld quality.

3) Due to the compression and cooling of the arc by argon flow, the welding stress and deformation is small, the arc heat concentration and high temperature argon, can ensure that the weld root penetration, small heat-affected zone joints, small welding deformation and cracking tendency . Especially for large welded steel air quenching tendencies.

4) tungsten arc stability, even in a small welding current (<10A) is still under stable combustion, especially for thin, thin plate welding materials.

5) heat and filler wire can be controlled, and therefore easy to adjust the heat input can be welded at various locations, but also the ideal way to achieve blooming side welding.

6) As the filler wire does not pass through the arc, it does not produce spatter, weld appearance.

7) Ar is a single atom gas, small heat capacity, low thermal efficiency, heat consumption, stable combustion of the arc is very beneficial, even at low current conditions and a long arc, the arc remains stable, easy to operate, easy to control weld quality for difficult trails pipe welding position all-position welding.

TIG welding is easy to operate because of good quality, in recent years, it has become a common method for the power generation companies in the installation and maintenance of boiler heating surface tubes welded. Under the conditions of site maintenance, and operation of the welding position by space constraints, process method commonly used is bottoming TIG welding SMAW cover the whole face or the use of TIG welding.