Size: 219-3620 - mm wall thickness: 5-30 mm
Material: L245 - X70
Standard: GB9711
Application: external anticorrosive processing or black paint, often used in oil, natural gas transportation pipeline steel pipe. Among them are divided into two level PSL1 and PSL2.API pipeline steel pipe is belong to the American standard of oil line pipe, line pipe is to put out the ground of oil, gas, water, pipeline through the pipeline to oil and gas industry enterprise. Line pipe including seamless pipe and welded steel pipe, the pipe end with flat end, with threaded end and socket end;Its connection way as the end of welding, coupling connection, socket connection, etc.With the development of the pipeline steel plate technology and the progress of welded pipe forming, welding technology, the application range of the pipe with welded pipe in gradually expanding, especially in the large diameter welded pipe class scope advantages more apparent, and cost factors, welded pipe has been dominant in the field of line pipe.
Spiral steel pipe will strip into welded pipe unit, the multichannel roll rolling, strip steel rolled up gradually, there is an open space form of round billet, adjust the quantity of the squeezing roller, make the weld gap control in 1 ~ 3 mm, and make joint flush on both ends.
1. If clearance is too large, resulting in a decrease of proximity effect, eddy current heat is insufficient, the joint between the weld crystal bad and incomplete fusion or crack generation.
2. The proximity effect increases, such as the gap is too small a result of welding heat is too big, cause the burning of the weld;Or weld after extrusion, rolling the deep pit formation, affect the surface quality of the weld.
Two edges of billet heating to welding temperature, under the extrusion of squeezing roller, to form a common metal grain interpenetrate, crystallization, eventually forming solid weld.If the spiral steel pipe extrusion pressure is too small, the amount of common crystal small, weld metal strength drops, stress produces after cracking;If the extrusion pressure is too large, will make molten metal being squeezed out of the seam, not only reduce the weld strength, and can produce a large number of inside and outside burr, even cause the welding seam defects such as.