Definition and classification of welded steel pipe

Welded steel pipe, also known as welded pipe, is a steel pipe made of steel plate or steel strip after being crimped and welded. Welded steel pipe has a simple production process, high production efficiency, many varieties and specifications, and less equipment, but its general strength is lower than that of seamless steel pipes. Since the 1930s, with the rapid development of high-quality strip steel continuous rolling production and the advancement of welding and inspection technology, the quality of welds has been continuously improved, the varieties and specifications of welded steel pipes have been increasing, and more and more fields have replaced non-ferrous steel. Seam steel pipe. Welded steel pipes are divided into straight seam welded pipes and spiral seam welded pipes according to the form of welds.

The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is fast. The strength of the spiral seam welded pipe is generally higher than that of the straight seam welded pipe, and the welded pipe with a larger diameter can be produced with a narrower billet, and the welded pipe with different pipe diameters can also be produced with a billet of the same width. However, compared with the same length of straight seam pipe, the length of the weld is increased by 30~100%, and the production speed is lower. Therefore, most of the welded pipes with smaller diameters use straight seam welding, and most of the welded pipes with large diameters use spiral welding.

1. Welded steel pipes for low-pressure fluid transportation are also called general welded pipes, commonly known as black pipes. It is a welded steel pipe for conveying general lower pressure fluids such as water, gas, air, oil and heating steam and other purposes. The wall thickness of the steel pipe is divided into ordinary steel pipe and thickened steel pipe; the form of the pipe end is divided into non-threaded steel pipe (smooth pipe) and threaded steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), which is an approximation of the inner diameter. It is customary to express in inches, such as 11/2 and so on. In addition to being directly used to transport fluids, welded steel pipes for low-pressure fluid transportation are also widely used as the original pipes of galvanized welded steel pipes for low-pressure fluid transportation.

2. Galvanized welded steel pipe for low-pressure fluid transportation is also called galvanized electric welded steel pipe, commonly known as white pipe. It is a hot-dip galvanized welded (furnace welded or electric welded) steel pipe used for conveying water, gas, air oil, heating steam, warm water and other general lower pressure fluids or other purposes. The wall thickness of the steel pipe is divided into ordinary galvanized steel pipe and thickened galvanized steel pipe; the form of the pipe end is divided into non-threaded galvanized steel pipe and threaded galvanized steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), which is an approximation of the inner diameter. It is customary to express in inches, such as 11/2 and so on.

3. Ordinary carbon steel wire casing is a steel pipe used to protect wires in electrical installation projects such as industrial and civil buildings, installation of machinery and equipment.

4. The straight seam electric welded steel pipe is a steel pipe with the weld seam parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe and so on.

5. Spiral seam submerged arc welded steel pipe for pressurized fluid transportation is a spiral seam steel pipe used for pressurized fluid transportation, which is a hot-rolled steel strip coil as a tube blank, often formed by warm spiral, and welded by double-sided submerged arc welding. The steel pipe has strong pressure bearing capacity and good welding performance. After various strict scientific inspections and tests, it is safe and reliable to use. The diameter of the steel pipe is large, the transportation efficiency is high, and the investment in laying pipelines can be saved. Mainly used for pipelines for transporting oil and natural gas.

6. Spiral seam high-frequency welded steel pipe for pressurized fluid transportation is made of hot-rolled steel coil as a tube blank, often formed by warm spiral, and welded by high-frequency lap welding. Welded steel pipe. The steel pipe has strong pressure bearing capacity and good plasticity, which is convenient for welding and processing. After various strict and scientific inspections and tests, it is safe and reliable to use. The steel pipe has a large diameter and high transportation efficiency, and can save investment in laying pipelines. Mainly used for laying pipelines for transporting oil, natural gas, etc.

7. Generally, the spiral seam submerged arc welded steel pipe for low-pressure fluid transportation is made of hot-rolled steel coil as the tube blank, and is often formed in a warm spiral. It is made of double-sided automatic submerged arc welding or single-sided welding for water, gas and air Submerged arc welded steel pipes for general low-pressure fluid transportation such as steam and steam.

8. The spiral seam high-frequency welded steel pipe for general low-pressure fluid transportation is made of hot-rolled steel coil as the tube blank, which is often formed by warm spiral, and is welded by high-frequency lap welding. It is used for general low-pressure fluid transportation. .

9. Spiral-welded steel pipes for piles are made of hot-rolled steel coils as tube blanks, often formed by warm spirals, and made of double-sided submerged arc welding or high-frequency welding. They are used for foundation piles such as civil construction structures, wharfs, and bridges. Use steel pipes.