Pipeline transportation is a long-distance transportation of liquid and gas materials using pipelines as a means of transportation.It is a special transportation method for transporting petroleum, coal and chemical products from the production place to the market, and it is a special part of trunk transportation in the unified transportation network. The casings used for oil transportation are mostly seamless pipes, because the seamless pipes are perforated by the whole round steel, without welds, with high pressure resistance and good toughness.

Austenitic stainless steel refers to stainless steel with austenitic structure at room temperature. When the steel contains about 18% Cr, 8%~10% Ni, and about 0.1% C, it has a stable austenite structure. Austenitic chromium-nickel stainless steel includes the famous 18Cr-8Ni steel and high Cr-Ni series steel developed on this basis by increasing the content of Cr and Ni and adding Mo, Cu, Si, Nb, Ti and other elements.

According to the standard requirements, the dimensional inspection of seamless steel pipes mainly includes the wall thickness, outer diameter, length, curvature, ovality and end face shape of the steel pipe.

Welded pipe misalignment refers to the parallel deviation of the strip along the thickness direction due to the misalignment of the two edges of the strip at the forming butt joint of the steel pipe. The wrong side will cause the effective wall thickness of the steel pipe to decrease, which will affect the mechanical properties of the steel pipe to a certain extent. Due to the irreparability of the wrong side, the wrong side is one of the main factors causing the degradation of the steel pipe.

The hot extrusion process of seamless steel pipe is a pressure forming method, which is to place the tube blank in a pressure-resistant container, and apply external force to cause the tube blank to plastically deform under the state of three-dimensional compressive stress.

Because oil and gas pipelines are buried underground for a long time, they are very prone to corrosion problems due to soil, moisture and other factors. At present, pipeline corrosion in the petrochemical industry is mainly divided into two types: