The steel tube used for welding is steel plate or strip steel, which is divided into furnace welded pipe, electric welding (resistance welding) tube and automatic arc welding tube.There are two kinds of welded pipe and spiral welded pipe.The end shape is divided into round welded tube and different type (square, flat, etc.) welded pipe.The welded pipe is divided into the following categories due to its different materials and USES:

GB/t3091-1993 (low-pressure liquid conveying galvanized steel pipe).It is mainly used for conveying water, gas, air, oil and heating water or steam.It stands for quality Q235A steel.

GB/t3092-1993 (low-pressure liquid conveying galvanized welded steel pipe).It is mainly used for conveying water, gas, air, oil and heating hot water or steam.The representative material is: Q235A steel.

GB/t14291-1992 (mineral fluid conveying welded steel pipe).It is mainly used for welding steel pipe with straight seam of mine pressure, drainage and axial gas.Its representative material Q235A, b-grade steel.GB/T14980-1994 (low-pressure fluid delivery with large diameter welded steel pipe).It is mainly used for low-pressure fluid, such as water, sewage, gas, air and heating steam etc.It stands for quality Q235A steel.

GB/t12770-1991 (mechanical structure welded steel tube with stainless steel).Mainly used in mechanical, automobile, bicycle, furniture, hotel and hotel decoration and other mechanical parts and structural parts.Its representative materials are 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.

GB/t1271-1991 (fluid conveying stainless steel welded steel pipe).Mainly used for conveying low-pressure corrosive media.The representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc.