Straight seam steel pipe and spiral steel pipe is welded steel pipe, just a straight seam steel pipe is high frequency welding and submerged arc welding, spiral submerged arc welding of pipe welding is widely used them in the construction of national production, straight seam steel pipe and spiral steel pipe production process is different and therefore have many differences, the following specific talk about the difference between straight seam steel pipe and spiral steel pipe. Longitudinal welded pipe production process is simple, main production process for high frequency straight seam steel pipe and straight seam submerged arc-welded steel tubes, straight-seam pipes of high production efficiency, low cost, rapid development. High strength of spiral welded pipe than longitudinal welded pipe, the main production was submerged arc welding, spiral steel pipe can use the same width of the billet production of different diameter of the pipe, you can also narrow the billet production of large diameter welded pipes. But compared with the straight seam pipe of the same length, weld length 30~100%, and lower production rate. Therefore, most small-diameter pipe used straight seam welding, large diameter thick-walled double submerged arc welded longitudinal seam submerged arc welding of steel pipe is mostly used. In industry production larger caliber thick wall straight sewing pipe Shi will using t-welding technology, is a paragraph short of straight sewing pipe again for docking, received into meet engineering need of length, t-welding volume tube defects of chances also greatly improve, and t-welding volume tube weld at of welding residual stress larger, weld metal often in three to stress state, increased has produced crack of possibilities.