Contrast of Welded Steel Pipe

Conveying pipe by the different pipe process, can be divided into seamless steel tube (SML), mainly as oilfield gathering tube and small diameter internal high pressure natural gas pipeline, used for long distance oil and gas pipeline of few in number, the vast majority of long distance pipeline is to use high frequency straight seam welded pipe (ERW), spiral submerged arc welding pipe (SSAW), straight seam submerged arc welding pipe (LSAW steel pipe) three. The table below for the process features of several kinds of steel pipe and quality performance contrast:

High frequency straight seam welded pipe (ERW) according to the welding process is divided into different induction welding and resistance welding two forms, using hot rolled wide strip coil as raw material, through the continuous forming, bending, welding, heat treatment, sizing, straightening, cutting process, such as weld short compared with spiral welded pipe, high dimensional accuracy, uniform wall thickness, good surface quality, high pressure, etc. But the disadvantage is that only production of small diameter thin wall pipe, weld easy generation resistant, incomplete fusion, trench corrosion defects. Widely used such as city gas, crude oil transportation.

Spiral submerged arc welding pipe (SSAW) steel strip coil direction when the forming Angle with the center line of the pipe forming (adjustable), forming and welding, the welding seam into spiral, advantage is that the same specifications of the steel strip can produce various specifications of the steel tube diameter, raw material range is larger, the weld can avoid the principal stress, the stress condition is good, the disadvantage is that poor geometry size, weld length compared with straight seam length, easy to produce cracks, porosity, slag, weld defects such as welding, welding stress is tensile stress state. The rules and regulations of general oil and gas long distance pipeline design of spiral submerged arc welding pipe can only be used for 3, 4 regions. Abroad will improve after this process will be raw materials instead of steel plate, forming and welding, then welding and lean, cold expanding, after welding, the welding quality is close to UOE tube, at home there is no such process, is the direction of the mild steel pipe factory to improve in our country. "West-east gas" spiral tube is still used by traditional craft production, only the pipe hole enlargement. The United States, Japan and Germany, on the whole, negative SSAW, don't think it is proper to use SSAW trunk; Canada and Italy part use SSAW, Russia a small amount of use of SSAW, and have made a very strict complementary condition, due to historical reasons, most domestic trunk or use SSAW.