According to the regulations of GB / T3092 "low pressure fluid delivery with welded steel pipe" standard, the nominal diameter of the welded pipe is 6 ~ 150mm, nominal wall thickness is 2.0 ~ 6.0mm, the length of weld- ed pipe is usually between 4m and 10m, it can be produced in fixed ruler or double ruler. Steel pipe surface q- uality should be smooth, do not allow folding, cracks, stratification, welding and other defects exist. The surfa- ce of the pipe is allowed to have minor defects such as scratches, scratches, weld misalignment, burns and scarring that do not exceed the negative wall thickness. Allows weld thickening at the wall and the presence of internal welds.
