The production process of straight seam steel pipe is relatively simple. The main production processes include high-frequency welding straight seam steel pipe and submerged arc welding straight seam steel pipe. The straight seam steel pipe has high production efficiency, low cost and rapid development.The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. The main production process is submerged arc welding.Compared with the straight seam steel pipe of the same length, the weld length of spiral steel pipe increases by 30-100%, and the production speed is low.
In terms of welding process, the welding method of spiral steel pipe is the same as that of straight seam steel pipe, but there are inevitably many T-joints in the straight seam steel pipe, so the probability of welding defects is greatly increased, and the welding residual stress at the T-joint is large, and the weld metal is often in the three-dimensional stress state, which increases the possibility of cracks.Moreover, according to the regulations of submerged arc welding process, each weld should have an arc striking and arc extinguishing position, but each straight seam steel pipe can not meet this condition when welding the circular seam, so there may be more welding defects at the arc extinguishing position.