The Difference And Use Of ERW, LSAW And SSAW Steel Pipe

The Difference And Use Of ERW, LSAW And SSAW Steel Pipe

High frequency straight seam (ERW steel pipe) by divided into induction welding and resistance welding welding way, USES the hot rolled wide coil for raw materials, through continuous forming, bending, welding, heat treatment, sizing, straightening, cutting compared with screw, with a short weld, high dimensional accuracy, wall thickness uniformity, good surface quality, high pressure, etc. But the disadvantage is that only small and medium caliber thin wall pipe can be produced. Fusion, groove corrosion defects. Currently widely used areas are urban natural gas and crude oil product transportation.

Straight seam submerged arc (LSAW steel pipe) is a single medium thick plate as raw material, the steel plate is pressed (rolled) in the mold or forming machine, using double-sided submerged arc welding, diameter expansion. The finished product has a wide range of specifications, good toughness, plasticity, uniformity and densification of weld seams, and has the advantages of large pipe diameter, thick pipe wall, high pressure resistance, high temperature resistance and corrosion resistance. In the construction of high strength, high toughness and high quality long oil and gas transmission pipelines, the steel pipe is mostly large-diameter thick wall straight seam arc buried pipe. According to API standards, submerged arc straight pipe is the only designated type of pipeline for large oil and gas pipelines passing through class I and II areas such as alpine regions, seabed, and densely populated urban areas. According to different forming methods, it can be divided into U0E/JCOE/HME.

Spiral submerged arc welding (SSAW steel pipe) refers to that when the pipe is rolled, its advancing direction and the forming pipe center line have forming Angle (adjustable), welding during forming, and the weld line forms a spiral line. The advantage is that the same specification can produce a variety of diameter specifications of steel pipe, the raw material to adapt to a wider range, weld can avoid the main stress, and the stress is better. The disadvantage is poor geometry. The length of the weld is longer than that of the straight seam. It is prone to crack, porosity, slag inclusion and welding deviation. For welding defects, welding stress is in tensile stress state. – The general design code for long oil and gas pipelines states that spiral submerged arcs can only be used in Category 3 and category 4 areas. After foreign process improvement, the raw material is changed to steel plate separation forming and welding. After pre-welding and fine welding, the diameter of weld is enlarged after cold welding. Welding quality is similar to UOE tube.