types of commonly used steel pipes

At present, the commonly used welded steel pipes can be divided into three kinds of continuous welding (forging)
According to the different welding process used in production, steel pipe, resistance welded steel pipe and arc welded steel pipe.
Arc welding steel pipe is a steel pipe produced by arc welding method.
It is characterized by the complete metallurgical bonding of the welded joints, and the mechanical properties of the joints can be fully achieved or close to the mechanical properties of the parent metal.
After proper heat treatment and non-heat treatment
Destructive Inspection, the use conditions of arc welding of straight-seam steel pipes can be used to replace seamless steel pipes.
According to the different weld types, the arc welded steel pipe can be divided into two types: Longitudinal welded pipe and spiral welded pipe.
According to the different protection methods used in the welding process, the welded steel pipe can be divided into two types: Submerged arc welded steel pipe and molten gas welded steel pipe.
Spiral seam welded steel pipe during welding, the welding torch and the weld are in the relative motion of the combination of rotating motion and linear motion, and the weld is spiral.
Compared with the straight seam steel pipe, the length of the weld is longer, and the stress of the weld is two-
Size tensile stress.
Therefore, it usually applies to non-
The design temperature is 0 °C to 200 °C, and the toxic medium pipe with a design pressure of no more than 1. 0 MPa.
However, the production of spiral welded pipe can be continuously operated, with high production efficiency and high material utilization rate, which is convenient for large
Large-scale production.
At present, the commonly used steel pipe standard is SY/T5037 \"spiral seam submerged-
Welding steel pipe for ordinary fluid transportation, etc.
The specification range of SY/T5037 is DN250 ^ DN2500 and the wall thickness is 15mm to 5. 0mm to 20. 0mm.
There are three kinds of materials: Q195, q2 15 and q2 35.
The applicable media are water, gas, air, heated steam and other common fluids. .
Common standard GB12771-for straight-seam arc welded steel pipes-
2008 \"stainless steel welded pipe for fluid transportation\", hg50237.
1 ~ 4 \"aoshi stainless steel welded pipe\" and so on.
Among them, the standard specification range of GB12771 is DN6 ~ DN560, wall thickness from 0. 3mm ~ 14.
0mm a total of 29 specifications, the material grades are: crni9, 0Cr19Ni9, 00Cr19Ni11, 0crni10ti, 0cr17ni12mo
At present, there is no standard for direct seam arc welding of carbon steel and alloy steel pipes suitable for petrochemical plants in China.
When this type of welded steel pipe is used in the design, many manufacturing requirements are often required in the design documents.
This is unlikely. convenient.
Therefore, it is hoped that the state or industry will develop such standards for designers and manufacturers as soon as possible.
Under normal circumstances, straight welded pipes are not allowed for extreme or highly dangerous media delivery.
Continuous welding (forging)
Continuous welding of steel pipes (forging)
The steel pipe is heated inside the heating furnace, and then the formed edge is welded together with the pressure method to form a straight seam steel pipe.
It is characterized by high production efficiency and low production cost, but the metallurgical combination of welded joints is incomplete, the weld quality is poor, and the overall mechanical properties are poor.