The stainless steel slip on flange
and the stainless steel pipe fittings are fixed by TIG welding technology, and the flange sealing surface is self-welding welded, and the flange non-sealing surface is welded by wire to realize the flange connection function.
Flange connection is to fix two pipeline equipment and pipe fittings on one flange first, between the two flanges, and add flange seals, bolted together to complete the connection. Flange connection is easy to use and can withstand large pressure. It is an important connection method for pipeline construction. TIG welding is the first choice for fixing stainless steel flanges and stainless steel pipe fittings.
Selection of welding equipment
1.1 Welder: Tungsten argon arc welding machine, such as WSM series DC tungsten pulse argon arc welding machine, has automatic function of current ramp and current decay.
2 welding torch: common welding torch is divided into water-cooled and air-cooled, the former is used for high current (≥150A) welding, and the latter is used for small current (≤150A) welding.
Selection of welding materials
2.1 Argon: It has excellent protection. It does not chemically interact with metal or dissolve in metal. It makes the metallurgical reaction of the weld pool simple and easy to control, so it provides high quality welds. Good condition. The arc is very stable in argon combustion, and it is still stable in the case of small current welding (<10A). It can be welded to the active metal which is easy to be oxidized and nitrided, the high melting point ferrous metal and the dissimilar metal. Atomic energy, petrochemical, power station boilers, machinery and other fields are widely used. In order to ensure the best welding quality, argon purity is usually required to reach 99.99% or more.
2.2 Welding wire: The argon welding wire type is 304, 308, 308L, 316L, etc. The selection principle is that the mechanical properties of the weld metal should be higher than or equal to the limit specified by the base metal. When necessary, other properties should not be low. Corresponding requirements for the base metal; or mechanical properties and other properties to meet the technical requirements specified in the design documents.
2.3 Tungsten: Because pure tungsten is not easy to lead arc, it is generally made of tantalum tungsten or tantalum tungsten. The tungsten beam of the tungsten electrode is slender, the heat is concentrated, the life is long, and the arc is easy to be induced. More importantly, the radioactive hazard is much smaller than that of the thorium tungsten. Therefore, it is recommended to use the thorium tungsten electrode as the electrode for tungsten gas shielded welding. If the surface of the tungsten electrode is brown, yellowish green or blue, the end oxidation is severe and should be re-polished before use.