angle welding standards Normally, steel pipes are welded for welding. The same way connect the sections of the pipeline in case the reinforcement is made of structural steels or pipes made of high-alloyed alloys. Different metals are suitable for different welded technologies and electrodes. Copper and aluminum elements are also connected by welding or soldering, but this requires a special argon-arc device that produces an electric arc in an argon gas medium, and aluminum and copper wires are used as an electrode. 
Welding is also suitable for polymer pipes, but in this case special - thermal under pressure. Such a connection is used in the manufacture of fittings, which are assembled from cut pieces of pipes.
The basic normative document regulating corner welding of pipes is GOST 16037-80.Pairing at an angle for welding of pipelines is realized with the help of some types of joints:
- Angle coupling of pipes of the same diameter, without cutting edges, by unilateral welding seam( GOST-U16).The edges of the pipes must be ground and adjusted to each other without any gap.
- Coupling of a pipe with a union with a one-sided seam without a partition( GOST-U17, U18).Between the edges of the minimum gap.
- Angle welding with edge mowing using a one-sided seam, which is denoted by the code number U19.The edge of the lower pipe is almost welded without machining, and the chamfer is removed from the top.
- Welding at an angle with bevel on a cylindrical edging. One-sided seam( Y20) is performed. The lower pipe edge goes into operation without machining.
- Angular interface with partition. Inside the tube, an annular insert is placed, and the seam is made from the outside( Y21).
Square pipes are welded in accordance with the same rules.
Variety of angular welding
All types of welding, whether it is argon-arc, electric arc or gas, begins with the fact that it is necessary to fit the ends. The gap between the elements should be between 0.5 mm and 1.5 mm. 
Welding without a bevel of edges is applied only on pipes, in which the wall thickness is sufficiently small - from 1 to 6 mm. The process of joining begins with pinching the elements with spot welds, and then continue to control the position of the pipes and perform annular joint welding along the outer edge.
Angle mating, which has a one-sided end, assumes a chamfer made at an angle of 50 °.With a two-sided section, two chamfers are required at an angle of 30 °.The clearance is permissible up to 1-2 mm in the first case and 2-5 mm in the second. Therefore, in these cases, the ideal edge of the elements is not important. In this way, pipes with a wall thickness of 2 to 20 mm are joined. 
For angular welding with edge milling and section, the wall thickness should be from 6 to 60 mm, the width of the section should be from 18 to 48 mm. Pipes of such dimensions are welded using a special technique for filling the weld pool.
