1. Welded steel pipe for low-pressure fluid transportation (GB/T3092-1993) is also called general welded pipe, commonly known as black pipe. It is a welded steel pipe used for conveying general lower pressure fluids such as water, gas, air, oil and heating steam and other purposes. The thickness of the steel pipe is divided into ordinary steel pipe and thick steel pipe; the pipe end form is divided into non-threaded steel pipe (light pipe) and threaded steel pipe.
The specification of the steel pipe is expressed by the nominal diameter (mm), and the nominal diameter is an approximate value of the inner diameter. It is customary to use inches, such as 11/2. The welded steel pipe for low-pressure fluid transportation is mainly used as a raw pipe for galvanized welded steel pipe for low-pressure fluid transportation, in addition to being directly used for conveying fluid.
2. Galvanized welded steel pipe for low pressure fluid transportation (GB/T3091-1993) is also called galvanized electric welded steel pipe, commonly known as white tube. It is a hot dip galvanizing (furnace welding or electric welding) steel pipe for transporting water, gas, air oil, heating steam, warm water and other general lower pressure fluids or other purposes. The thickness of the steel pipe is divided into ordinary galvanized steel pipe and thick galvanized steel pipe; the connection end form is divided into non-thread galvanized steel pipe and threaded galvanized steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), and the nominal diameter is an approximate value of the inner diameter. It is customary to use inches, such as 11/2.
3. Ordinary carbon steel wire casing (GB3640-88) is a steel pipe used to protect electric wires in electrical installation projects such as industrial and civil construction, installation machinery and equipment.
4. Straight seam electric welded steel pipe (YB242-63) is a steel pipe whose weld is parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on.
The steel pipes are generally divided into two categories, one is welded steel pipe and the other is seamless steel pipe. Welded steel pipes, also called welded pipes, are steel pipes made by welding steel plates or strips after being crimped. The welded steel pipe has simple production process, high production efficiency, many varieties and specifications, and less equipment, but the general strength is lower than that of seamless steel pipe.
Since the 1930s, with the rapid development of high-quality strip continuous rolling production and the advancement of welding and inspection technology, the quality of welded joints has been continuously improved, the variety specifications of welded steel pipes have been increasing, and more and more fields have replaced Seam steel pipe. Welded steel pipes are divided into straight welded pipes and spiral welded pipes in the form of welds.
The blanks used for ssaw steel pipes are steel plates or strip steels, which are divided into furnace welded pipes, electric welding (resistance welded) pipes and automatic arc welded pipes due to different welding processes. Due to the different welding forms, it is divided into straight seam welded pipe and spiral welded pipe. Because of its shape, it is divided into round welded pipes and special-shaped (square, flat, etc.) welded pipes. Welded pipes are divided into the following varieties due to their different materials and uses:
GB/T3091-1993 (galvanized welded steel pipe for low pressure fluid transport). It is mainly used to transport water, gas, air, oil and heating water or steam, such as general lower pressure fluids and other uses. It stands for material Q235A grade steel.
GB/T3092-1993 (galvanized welded steel pipe for low pressure fluid transport). It is mainly used to transport water, gas, air, oil and heating water or steam, such as general lower pressure fluids and other uses. Its representative material is: Q235A grade steel.
GB/T14291-1992 (mineral fluid transport welded steel pipe). It is mainly used for straight seam welded steel pipes for mine pressure, drainage and shaft discharge. It stands for material Q235A, B grade steel.
GB/T14980-1994 (large diameter electric welded steel pipe for low pressure fluid transportation). It is mainly used to transport low pressure fluids such as water, sewage, gas, air, heating steam and other uses. It stands for material Q235A grade steel.
GB/T12770-1991 (stainless steel welded steel pipe for mechanical structure). Mainly used in machinery, automobiles, bicycles, furniture, hotel and restaurant decoration and other mechanical parts and structural parts. It represents materials 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, and the like.
GB/T12771-1991 (stainless steel welded steel pipe for fluid transportation). Mainly used to transport low pressure corrosive media. Representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, and the like.
Longitudinally submerged arc welding pipe has simple production process, high production efficiency, low cost and rapid development. The strength of the spiral welded pipe is generally higher than that of the straight welded pipe. It is possible to produce a welded pipe with a large diameter by using a narrow blank, and it is also possible to produce a welded pipe having a different pipe diameter by using a blank of the same width. However, compared with the straight pipe of the same length, the weld length is increased by 30 to 100%, and the production speed is low.
Therefore, most of the smaller diameter welded pipes are straight seam welded, and the large diameter welded pipes are mostly spiral welded. (For example, the pipeline used in the West-East Gas Pipeline is a spiral welded pipe, and Taiyuan Heavy Industries produces a spiral-welded pipe machine.) There is a relatively new technology called “thermal reduction”, which is to re-roll the welded pipe to improve its surface quality. And dimensional tolerances, making the overall performance close to seamless steel pipe.