SSAW and LSAW Steel Pipe

Spiral welded pipe is carbon steel or low carbon alloy steel strip at a certain helix angle (called molding angle) rolled into a tube, and the tube made of welded joints, which can be used to narrow band production of large diameter steel pipe. Spiral welded pipe is mainly used for oil and gas pipelines. There are one-sided spiral pipe welding and double-sided welding, pipe should ensure that hydrostatic test, weld tensile strength and performance of cold-formed to meet the requirements.   LSAW steel pipe is produced, and spiral welded pipe is hot-rolled coil production. Hot strip rolling process unit has a series of advantages, have access to the production of high quality metallurgical process pipeline capacity. For example, the output with the bench in order to accelerate the cooling water cooling system, which allows the use of low alloy composition to achieve the specific level of strength and low temperature toughness to improve the weldability of the steel. However, this system is basically no steel production plant. Alloy content Coil (carbon equivalent) is often lower than a similar grade steel, which also improves weldability spiral welded pipe. For the welding process, the welding and spiral welded pipe joints straight consistent approach, but inevitably there will be a lot of Longitudinal welds T, so the probability of the existence of welding defects is also greatly improved, and the welding residual stress at the weld T larger weld metal often in three-dimensional stress state, increasing the likelihood of cracks. Someone asked: spiral welded steel pipe and welded steel What is different? There is a kind of number two steel. In fact, no need entangled in this issue. Spiral welded steel pipe itself is a welded steel, but in the production process is somewhat different Bale. Specifically, in the form of weld pipe into Longitudinal and spiral welded pipe. Not the same as the general use of both. General DN350 above, will be used spiral steel pipe, spiral steel pipe spiral weld because, so the pressure of the liquid will be distributed on each side to withstand the tube, to enhance the strength of the pipe. If large pipe while generally rolled steel plate welded directly straight, need a larger plate, greatly increasing the difficulty of making, so will the use of larger diameter coil. As for which is good, because the scope is inconsistent, do not have to get to the bottom. Spiral Pipe (double-sided spiral submerged arc welded pipe) is a strip coil as raw material, often warm extrusion molding, automatic double-sided submerged arc welding process wire spiral seam steel pipe. Another one is welded steel pipe, steel roll after it is welded to the vertical seam welds. Spiral welded pipe is welded steel spiral roll, spiral-shaped seam. Trends in the development of large-diameter pipes, high strength. With the increase of the diameter of the pipe, the steel grade increases, the greater the ductile fracture tip steady expansion trend. According to the test showed that the U.S. research institutions, spiral welded pipe and Longitudinal although the same as a level, but spiral welded pipe with high impact toughness. Transmission pipelines due to the amount of change in the actual operation, the pipe is subjected to random alternating load effect. Understand the low cycle fatigue strength of steel, for the life of the pipeline judge has important significance. According to the measurement results, the fatigue strength of spiral welded seamless and ERW pipe with the same test data with seamless and resistance tubes located in the same area, and submerged arc welded pipe than the average higher.