Welded steel pipe, also known as welded pipe, is a steel pipe made of steel plate or steel strip after crimping and forming. The welded steel pipe has simple production process, high production efficiency, many varieties and specifications and less equipment, but its general strength is lower than that of seamless steel pipe. Since 1930s, with the rapid development of high-quality strip continuous rolling production and the progress of welding and inspection technology, the weld quality has been continuously improved, and the varieties and specifications of welded steel pipes have been increasing day by day, and seamless steel pipes have been replaced in more and more fields. Welded steel pipes are divided into straight welded pipes and spiral welded pipes according to the form of welds.
The longitudinal welded pipe has the advantages of simple production process, high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight welded pipe. Welded pipes with larger pipe diameters can be produced with narrower blanks, and welded pipes with different pipe diameters can also be produced with blanks with the same width. However, compared with the straight seam pipe with the same length, the weld length increases by 30 ~ 100%, and the production speed is lower.
Therefore, straight seam welding is mostly used for small diameter welded pipes, and spiral welding is mostly used for large diameter welded pipes.
1. Welded steel pipe for low-pressure fluid transmission (GB/T3092-1993) is also called general welded pipe, commonly known as black pipe. It is a welded steel pipe used for conveying water, gas, air, oil, heating steam and other low-pressure fluids and other uses. The joint wall thickness of steel pipes is divided into ordinary steel pipes and thickened steel pipes; The type of nozzle end is divided into without screw pipe (smooth tube) and with screw pipe. The specification of steel pipe is expressed by nominal diameter (mm), which is the approximate value of inner diameter. It is usually expressed in inches, such as 11/2, etc. Welded steel pipes for low-pressure fluid transportation are not only directly used for fluid transportation, but also widely used as raw pipes of galvanized welded steel pipes for low-pressure fluid transportation.
2. Galvanized welded steel pipe for low-pressure fluid transmission (GB/T3091-1993) is also called galvanized welded steel pipe, commonly known as white pipe. It is a hot dip galvanized welded (furnace welding or electric welding) steel pipe for conveying water, gas, air oil, heating steam, warm water and other generally low pressure fluids or other purposes. The joint wall thickness of steel pipe is divided into ordinary galvanized steel pipe and thickened galvanized steel pipe; The form of nozzle end is divided into galvanized steel pipe without thread and galvanized steel pipe with thread. The specification of steel pipe is expressed by nominal diameter (mm), which is the approximate value of inner diameter. It is usually expressed in inches, such as 11/2, etc.
3. Ordinary carbon steel wire bushing (GB3640-88) is a steel pipe used to protect wires in electrical installation projects such as industrial and civil buildings and installation of machinery and equipment.
4. Longitudinal welded steel pipe (YB242-63) is a steel pipe whose weld is parallel to the longitudinal direction of the steel pipe. It is usually divided into metric welded steel pipes, welded thin-walled pipes, transformer cooling pipes and so on.
5. Spiral seam submerged arc welded steel pipe (SY5036-83) for pressure fluid transportation is a spiral seam steel pipe with hot rolled steel strip coil as tube blank, spiral forming at normal temperature and welding by double-sided submerged arc welding, which is used for pressure fluid transportation. The steel pipe has strong bearing capacity and good welding performance, and it is safe and reliable to use after various strict scientific inspections and tests. The steel pipe has large caliber, high conveying efficiency and can save the investment in laying pipelines. Pipeline mainly used for transporting oil and natural gas.
6. Spiral seam high-frequency welded steel pipe (SY5038-83) for pressure fluid transportation is a spiral seam high-frequency welded steel pipe for pressure fluid transportation, which is made of hot-rolled steel strip coil, spirally formed at constant temperature and welded by high-frequency lap welding. Steel pipe has strong bearing capacity and good plasticity, which is convenient for welding and processing. Through various strict and scientific inspections and tests, it is safe and reliable to use, with large steel pipe diameter and high conveying efficiency, and can save the investment in laying pipelines. Mainly used for laying pipelines for transporting oil, natural gas, etc.
7. Spiral seam submerged arc welded steel pipe (SY5037-83) for general low-pressure fluid transportation is a submerged arc welded steel pipe for general low-pressure fluid transportation such as water, gas, air and steam, which is made of hot rolled steel strip coil as tube blank, spiral forming at constant temperature and automatic submerged arc welding on both sides or single-side welding method.
8. Spiral seam high-frequency welded steel pipe (SY5039-83) for general low-pressure fluid transportation is made of hot-rolled steel strip coil, which is spirally formed at normal temperature and welded by high-frequency lap welding.
9. Spiral welded steel pipe for pile (SY5040-83) is made of hot-rolled steel strip coil as pipe blank, spiral forming at constant temperature, double-sided submerged arc welding or high-frequency welding, which is used for foundation piles of civil buildings, docks, bridges and other steel pipes.