1：Welded  pipe (GB/T3092-1993) used in Low-pressure fluid delivery, also known as the general welded pipe, commonly known as black tube. It is the welded steel pipe that used to transport of water, gas, air, oil and heating steam, and other generally fluids with lower pressure. Steel pipe is divided into ordinary steel pipe and thickened pipe according wall thickness; is divided into non-threaded steel pipe (light pipe) and threaded steel pipe according to the form of pipe end. The specifications of the steel pipe are denoted by nominal caliber (mm), and the nominal caliber is the approximate value of the inner diameter. It traditionally uses inches to express, such as 11/2 and so on. Welded steel pipe used in Low-pressure fluid delivery in addition to directly use for the transport of fluid, but also is used as the original tube of galvanized welded steel pipe used in Low-pressure fluid delivery. 

2. Galvanized welded steel pipe (GB/T3091-1993) used in Low-pressure fluid transmission, also known as galvanized welded steel pipe, commonly known as white tube. It is the hot dipping galvanized welded (butt weld or electrowelding) steel pipe used to transport water, gas, air oil and heating steam, warm water and other generally fluids in lower pressure. Steel pipe is divided into ordinary galvanized steel pipe and thick galvanized steel pipe according to wall thickness; is divided into non-threaded galvanized steel pipe and threaded galvanized steel pipe according to the form of pipe end. It traditionally uses inches to express, such as 11/2 and so on. 

3. Ordinary carbon steel electric wire conduit (GB3640-88) is used in electrical installation ( such as the industrial and civil construction and installation of electrical equipment and other works) to protect the wire of the steel pipe. 

4. LSAW steel pipe (YB242-63) is the pipe that the weld longitudinally parallel to steel pipe. It is usually divided into metric welded steel pipe, welded thin-walled pipe, transformer cooling tubing and so on. 

5. SSAW steel pipe (SY5036-83) for pressurized fluid delivery is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature and welded by double-sided submerged arc welding, used for pressurized fluid delivery. The loading capacity of steel pipe is strong, welding performance is good, after a variety of strict scientific inspection and testing, it can be used safely and reliably. The diameter of steel pipe is big, transport efficiency is high, and it can save the laying of pipeline investment. So it is mainly used for conveying oil and gas pipelines. 

6. SSAW steel pipe (SY5037-83) used in general low-pressure fluid transmission is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature, use double-sided automatic submerged arc welding or single-sided welding method to weld. It is used for water, gas, air and steam and other general low-pressure fluid transmission. 

7. SSAW steel pipe (SY5040-83) used as pile is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature, use double-sided submerged arc welding or high-frequency welding to make. It is used for civil construction, wharf, bridge and other foundation pile steel pipe. 

8. ERW steel pipe used for pressurized fluid transmission (SY5038-83) is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature, welded by high-frequency lap welding, used for pressurized fluid transportation. The loading capacity of steel pipe is strong, plasticity is good, and it is easy to weld and machine shaping. After a variety of rigorous and scientific inspection and testing, the pipe is safe and reliable to use, the diameter of steel pipe is large, transport efficiency is high, and it can save the laying of pipeline investment.

9. ERW steel pipe (SY5039-83) used in general low-pressure fluid transmission is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature, use high-frequency lap welding to weld,. It is used for general low-pressure fluid delivery. 

The welded pipe is called the welded pipe for short, and the commonly used steel or steel strip is welded by the curled forming of the unit and the mold. The production process of welded steel pipe is simple, the production efficiency is high, the specifications are many, the equipment is less, but the general strength is lower than that of the seamless steel pipe. Since 1930s, with the rapid development of high-quality strip rolling production and progress of welding and testing technology, and constantly improve the weld quality, varieties and specifications of welded steel pipe is increasing, and in more and more fields especially in the heat pipe, who spare decorative tube, tube for low-pressure fluid etc. instead of the seamless steel tube. The production process of the straight welded pipe is simple, the production efficiency is high, the cost is low, and the development is fast. The strength of the spiral welded pipe is generally higher than that of the longitudinal welded pipe. The welded pipe with larger diameter can be produced with a narrow billet, and the welded pipes with different diameters can also be produced with the same width blank. But compared with the same length, the length of the weld increases by 30~100%, and the production speed is low.


Generally, the diameter of the pipe can be divided into outer diameter, inner diameter and nominal diameter. The outer diameter of the pipe for the pipe is represented by the letter D, followed by the outer diameter and wall thickness, for example, a seamless steel pipe with a outer diameter of 108.


1. The national standard of welded steel pipe 1, GB/T3091-1993 (galvanized steel pipe for low pressure fluid delivery). It is mainly used for transporting water, gas, air, oil, heating hot water or steam and other generally low pressure fluids and other use tubes. It represents Q235 a grade steel. 2, GB/T3092-1993 (galvanized steel pipe for low pressure fluid delivery). It is mainly used for transporting water, gas, air, oil, heating hot water or steam and other generally low pressure fluids and other use tubes. Its representative material is: Q235 a grade steel. 3, GB/T14291-1992 (mine fluid conveying welded pipe). It is mainly used for direct seam welded pipe used in mine pressure wind, drainage and shaft gas discharge. It represents the material Q235A, B grade steel. GB/T14980-1994 (large diameter welded steel pipe for low pressure fluid delivery). It is mainly used to transport water, sewage, gas, air, heating steam and other low-pressure fluids and other uses. It represents Q235 a grade steel. 4, GB/T12770-1991 (mechanical structure of stainless steel welded steel pipe). It is mainly used for the decoration of machinery, automobile, bicycle, furniture, hotel and hotel and other mechanical parts and structural parts. It represents the material 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb and so on.


Two, welded steel pipe classification A, welded pipe according to the shape of the weld can be basically divided into longitudinal welded pipe and spiral welded pipe two kinds: 1, straight welded steel pipe: simple production process, high production efficiency, low cost, rapid development. There are more straight welded pipes used in ordinary industry. 2, spiral welded steel pipe: the strength is generally higher than that of the longitudinal welded pipe. It can produce larger diameter welded pipe with a narrow billet, and can also produce pipes with different diameters with the same width blank, but compared with the straight seam pipe of the same length, the spiral welded steel pipe can be produced.

The weld length is increased by 30~100%, and the production speed is low. Therefore, the smaller diameter welded pipe is mostly welded longitudinally, while the large diameter welded pipe is mostly spiral welded. B, pipe use is divided into the following: 1, general: welded steel pipe welded steel pipe for conveying general low-pressure fluid. By Q195A, Q215A, Q235A steel. Also can be used for easy welding of mild steel. The other pipe to conduct water pressure, bending, flattening test, have certain requirements on the surface quality, usually the length of delivery 4-10m, often requires a fixed length (or size). The delivery pipe specifications with nominal diameter (mm or inches) nominal diameter and different pipe wall thickness, according to the provisions of general steel and thicker steel two, steel pipe end is divided according to form of threaded and non threaded two, 2. Galvanized welded steel pipe steel pipe: in order to improve the corrosion resistance of galvanized steel pipe general (clarinet). Galvanized steel hot galvanized steel and zinc two, hot dip galvanized layer thickness, the cost is low. 3, electro galvanized welded steel pipe for steelmaking with oxygen: oxygen blowing Tube, usually with a small diameter of the welded steel pipe, specifications from 3/8 inch -2 inch eight 08,10,15,20 or Q195-Q235 steel made. For corrosion protection, some aluminizing treatment. 4: ordinary carbon steel wire casing is welded steel pipe, used in concrete and distribution engineering structures, commonly used nominal diameter from 13-76mm. 5, metric standard Specification for welded steel pipe: seamless tube, with the outer diameter * wall thickness mm of welded steel pipe, with ordinary carbon steel, high carbon steel or low alloy steel components welding with cold, tropical or tropical welding after cold drawing method is made. The metric pipe and thin wall components divided, as ordinary structures, such as transmission shaft or transmission fluid, thin wall used in the production of furniture, lamps and so on, to ensure the steel strength and bending test. 6 roller tube: roller for welded steel pipe belt conveyor, Q215, Q235A, B steel and 20 steel, diameter 63.5-21 9.0mm. on the tube bending, end to perpendicular to the center line, ovality has certain requirements, the general pressure and flattening test. 7, transformer tube used in the manufacturing of transformer radiator tube and other heat exchangers, the common carbon manufacturing requirements, compressed, flaring, bending, hydraulic test tubes in fixed length or double. Length delivery of steel tube bending has certain requirements. 8, special-shaped tube: the ordinary carbon structural steel and 16Mn steel welded square tube, rectangular tube, pipe cap, empty plastic steel doors and windows with a pipe, mainly used for agricultural machinery components, steel window and door. 9: mainly used to produce welded thin-wall steel pipe furniture, toys, lamps etc.. In recent years, with the production of stainless steel tube is widely used, furniture, decoration, fences etc..