Straight seam steel pipe is parallel to the longitudinal weld and steel pipe steel pipe. Usually divided into metric welded steel pipe, welding thin-walled tube, transformer cooling tubing. Longitudinal production process is simple, high efficiency, low cost, rapid development. The strength of the spiral welded pipe is generally higher than the Longitudinal, can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different diameters of pipe. However, compared with the same length of straight seam pipe, the weld length increased by 30 to 100%, and lower production rate.