With the advancement of high-quality steel rolling production and the rapid development of welding and inspection technology, and improve weld quality, welded steel pipe increasing varieties and specifications, and in more and more areas instead of seamless steel tubes. Seam welded steel pipe in the form of divided Longitudinal and spiral welded pipe. Production methods by Category: Technology Category - arc welded pipe, ERW pipe, (high-frequency, low frequency) gas pipe, stove pipe. Longitudinal production process is simple, high production efficiency, low cost, rapid development. Spiral Welded Longitudinal generally higher than high, can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different pipe diameters. However, compared with the same length of straight seam pipe weld length of 30 to 100%, and lower production rate. Smaller diameter pipe straight seam welded, large diameter spiral welded pipe for the multi-use; press the pipe ends and shape into a circular pipe shaped (square, rectangular, etc.) pipe; by the use of different materials and fluids into mine transporting welded steel pipe, low pressure fluid galvanized welded steel pipe, welded steel pipe and other belt conveyor idlers. Under the current GB of standard size, from small to big sorted by diameter * wall thickness.