Steel Pipe Uses in Gas Project

Steel is the most widely used gas pipeline project. Its main advantages are: high strength, good toughness, large compressive stress, impact resistance, compactness, good plasticity, easy welding and heat treatment, thin wall thickness, saving the metal. But its poor corrosion resistance, the need to take appropriate anti-corrosion measures.

City main pipe seamless steel pipe and welded pipe two categories. High-strength seamless steel pipe, but the limited production process, the general small-diameter steel pipe DN200 the following costs. Welding more types of steel, welding can be divided into straight seam welded pipe and spiral welded pipe. Among them, straight seam welded steel pipe (hereinafter referred to as straight seam pipe) also includes LSAW pipe and high frequency resistance welding (ERW) steel pipe and other types. Spiral welded pipe (spiral submerged arc welded pipe) is a double-sided helical slit submerged arc welding (hsaw) pipe.

Comparison of straight seam and spiral pipe manufacturing process, the former has the following advantages:
In the manufacturing process of the spiral pipe, the residual stress is determined to be larger than that of the straight seam welded pipe. As the overall result of the pipe expansion process, the residual stress is close to zero, but the spiral shape can not do this.

② helical weld staggered, mostly in the range of 1.1 ~ 1.2mm, the standard requirements of the wrong side of the wall thickness is less than 10% of the thin-walled tube, the wrong side is difficult to meet the standard requirements, and straight seam pipe does not exist this problem;

③ Straight pipe compared to spiral weld poor mobility, serious stress concentration;


④ coil heat affected zone is greater than straight pipe, heat-affected zone is the key to quality;


⑤ helical geometry accuracy, to the construction site, as a corresponding, welding difficulties.