Welded steel pipe short, or common steel strip after curl forming unit and mold made of welded steel pipe. Welded steel pipe production process is simple, high production efficiency, variety specifications, less capital equipment, but the general strength less than seamless steel tubes. Since the 1930s, with the progress of high-quality steel rolling production as well as the rapid development of welding and inspection techniques, and continuously improve the quality of welds, welded steel pipe increasing varieties and specifications, and in more and more areas, especially in heat who spare tube, decorative tube, pipe and other aspects of the low-pressure fluid instead of seamless steel tubes.

Longitudinal production process is simple, high production efficiency, low cost, rapid development. Spiral Welded Longitudinal generally higher than, 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.

In general, the diameter of the tube can be divided into an outer diameter, inner diameter, nominal diameter. Pipe spiral steel pipe outer diameter is represented by the letter D followed by additional outer diameter size and wall thickness, for example, an outer diameter of 108 seamless steel tubes.

First, the national standard welded steel pipe

1, GB / T3091-1993 (low pressure fluid delivery galvanized welded steel pipe). Mainly used for conveying water, gas, air, oil and heating hot water or steam generally lower pressure fluid and other uses tubes. The representative of material Q235A grade steel.

2, GB / T3092-1993 (low pressure fluid delivery galvanized welded steel pipe). Mainly used for conveying water, gas, air, oil and heating hot water or steam generally lower pressure fluid and other uses tubes. The representative material for: Q235A grade steel.

3, GB / T14291-1992 (mine fluid delivery welded steel pipe). Mainly used for mine air pressure, drainage, gas discharge axis with straight seam welded steel pipe. The representative of material Q235A, B grade steel. GB / T14980-1994 (low pressure fluid with large-diameter welded steel pipe). Mainly used for conveying water, sewage, gas, air, and other low pressure steam heating fluid and other uses. The representative of material Q235A grade steel.

4, GB / T12770-1991 (mechanical structure with stainless steel welded pipe). Mainly used for machinery, automobiles, bicycles, furniture, hotel and restaurant decoration and other mechanical components and structures. The representative of material 0Cr13,1Cr17,00Cr19Ni11,1Cr18Ni9,0Cr18Ni11Nb like.