异型钢管是经冷拔制成各种异型的无缝钢管。异型钢管一般是根据断截面来区分的，按材料来说又可分为无缝异型钢管，铝合金异型管，塑料异型管。不锈钢异型管焊接时，应该注意事项：焊接6mm以下薄板的异型管时，要具备焊缝成型美观，焊接变形量小的特点。钨极从气体喷嘴突出的长度，以4-5mm为佳，在角焊等遮蔽性差的地方是2-3mm，在开槽深的地方是5-6mm，喷嘴至异型管的距离一般不超过5mm。焊接电弧的长度，焊接普通钢时以2-4mm为佳，而焊接不锈钢异型管时以1-3mm为佳，过长则保护效果不好。
Special-shaped pipe is made of various special-shaped seamless steel pipe by cold drawing. Special-shaped pipe is generally distinguished according to the broken section. According to material, it can be divided into seamless steel pipe special-shaped pipe, aluminum alloy special-shaped pipe, plastic special-shaped pipe. When welding stainless steel special-shaped pipe, we should pay attention to the following points: when welding the special-shaped pipe with thin plate under 6mm, it should have the characteristics of beautiful weld shape and small welding deformation. The length of tungsten pole protruding from gas nozzle is 4-5mm, 2-3mm in places with poor shielding ability such as fillet welding, 5-6mm in places with deep groove, and the distance from nozzle to special-shaped pipe is generally not more than 5mm. The length of welding arc is 2-4 mm for ordinary steel, 1-3 mm for stainless steel special-shaped pipe, and too long is not good for protection.
为使氩气很好地保护焊接熔池，和便于施焊操作，钨极中心线与焊接处工件一般应保持80-85°角，填充焊丝与管材表面夹角应尽可能地小，一般为0°左右。焊接异型管时，采用垂直特性的电源，直流时采用正极性。保护气体为氩气，纯度为99.99%。当焊接电流为50-50A时，氩气流量为8-0L/min，当电流为50-250A时，氩气流量为2-5L/min。有风的地方，务请采取挡网的措施，而在室内则应采取适当的换气措施。为防止焊接气孔之出现，焊接的异型管部位如有铁锈、油污等务必要先清理干净。对接打底时，为防止异型管底层焊道的背面被氧化，背面也需要实施气体保护。
In order to protect the weld pool well by argon gas and facilitate welding operation, the tungsten pole center line and the workpiece at the welding site should generally maintain an angle of 80-85 degrees, and the angle between the filler wire and the surface of the pipe should be as small as possible, generally about 0 degrees. Vertical power supply and positive polarity are used in welding special-shaped pipe. The protective gas is argon with a purity of 99.99%. When welding current is 50-50A, the argon flow rate is 8-0L/min, and when welding current is 50-250A, the argon flow rate is 2-5L/min. In windy areas, please take measures to block the net, while indoors should take appropriate ventilation measures. In order to prevent the occurrence of welding blowhole, it is necessary to clean the irregular welded pipe if there is rust and oil stain. In order to prevent oxidation on the back of the bottom weld of the special-shaped pipe, gas protection is also needed on the back of the weld.
