Differences between seamless steel pipes and seamed steel pipes

Date:2024-09-18Tags:seamless steel pipes, Welded steel pipe
There are many kinds of steel pipes on the market, such as seamed steel pipes, seamless steel pipes, etc., but many people don't know the difference between them. So what is the difference between seamed steel pipes and seamless steel pipes? Seamless steel pipes can be used to transport fluids (such as natural gas, oil, water, etc.), some solid materials, etc., and are also an economical steel material. Using steel pipes to make grids, columns, mechanical supports, etc. of building structures can reduce costs. Today, the editor has collected and sorted out the knowledge sharing about the difference between seamless steel pipes and seamed steel pipes for your reference.

Seamless steel pipes

Seamless steel pipes are made by perforating a whole round steel bar, and there is no weld on its surface. According to the production process, seamless steel pipes can be divided into multiple types such as top pipes, cold-drawn pipes, cold-rolled pipes, hot-rolled pipes and extruded pipes. If classified by cross-sectional shape, they are divided into round pipes and special-shaped pipes. There are many types of special-shaped pipes, including complex shapes such as star-shaped pipes, square pipes, oval pipes, triangular pipes and hexagonal pipes. According to the purpose, seamless steel pipes can also be divided into thin-walled pipes and thick-walled pipes, which are widely used in the manufacture of various types of fluid transportation and mechanical structural parts.
seamless steel pipes

Seamed steel pipe

Seamed steel pipe and seamless steel pipe are divided according to the processing form. Seamed steel pipe is generally welded. Welded steel pipe is divided into furnace welded pipe, electric welded (resistance welded) pipe and automatic arc welded pipe due to different welding processes. Due to different welding forms, it is divided into two categories: LSAW welded pipe and SSAW welded pipe. According to the shape of the end, it is divided into round welded pipe and special-shaped (square, flat, etc.) welded pipe. Welded steel pipe is made by rolling steel plate into a tube and welding it with butt seam or spiral seam. According to the manufacturing method, it is divided into welded steel pipe for low-pressure fluid transportation, spiral seam electric welded steel pipe, direct rolled steel pipe, electric welded pipe, etc. Seamless steel pipe can be used for liquid pneumatic pipelines and gas pipelines in various industries. Welded pipes can be used for water pipes, gas pipes, heating pipes, electrical pipes, etc.

Differences between seamless steel pipes and seamed steel pipes

1. Different appearance

The inner wall of the welded part of the seamed steel pipe generally has a weld, while the inner wall of the welded part of the seamless steel pipe generally has no weld.

2. Different pressures

The pressure of seamed steel pipes is generally above 1.6MPa, while the pressure of seamless steel pipes is generally above 7MPa.

3. Different uses

Different uses: Seamed steel pipes can be used to transport low-pressure fluids, such as gas, water, etc., so they are often used in the construction industry. Seamless steel pipes can not only be used to transport liquids, but also as structural parts, so they are often used in the machinery industry.

4. Different processes

Seamed steel pipes need to be rolled into coils first and then welded, while seamless steel pipes are produced in one go using rolling technology.

5. Different prices

Compared with seamed pipes, seamless pipes are more expensive, mainly because the processing technology of seamless pipes is more complicated. The construction process of seamed pipes is simple and widely used, so the price is relatively cheap.

The process difference between seamless steel pipes and seamed steel pipes

1. The maximum use pressure that seamed pipes can generally withstand is within 20 kg, which is the safest range of use. It is generally used for low-pressure fluids such as water, gas, and compressed air;
2. Seamless pipes can withstand ultra-high pressure, and of course their wall thickness will increase accordingly, which needs to be designed according to pressure requirements. It is generally used for high-temperature and high-pressure equipment such as high-pressure oil pipes and boiler pipes. There are also seamless pipes for structures, which depends on the design requirements.
3. At present, there are also some seamless steel pipes with seamless treatment. It is annealing the weld to eliminate the residual stress of the weld, so that the weld is equivalent to the parent material, and its pressure range is basically equivalent to that of seamless pipes. It can also be considered for use.
4. Of course, there are also some seamless steel pipes on the market that are drawn or rolled with core heads after the welded steel pipe is heated as a whole. They are mainly small specifications. This type of pipe is only a seamless pipe in terms of appearance, and its essence is not very good. Pay attention! According to the thickness of the pipe wall, it can be divided into three types: ordinary, thickened and thin-walled. It is mainly used in water and gas pipelines. So it is called water and gas pipes.
Electric welded steel pipes are made of low-carbon thin steel plates rolled into a tube shape and then welded with straight welds and spiral welds. Straight welds are mainly used for fluid pipelines with low pressure and low temperature. Spiral welds are mainly used for gas, natural gas, and % condensate pipelines.

Seamless steel pipes are generally formed by extruding molten steel through an annular slit and then forming it through stretching and other processing processes (seamless steel pipes can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, etc. according to different production methods), so there are no welds. In terms of performance, especially the pressure bearing capacity, it is greatly improved compared with ordinary steel pipes, so it is often used in high-pressure equipment. However, the pressure level is determined by the caliber and wall thickness, not by the weld, but the weld part of ordinary steel pipes is its weak link, and the quality of the weld is also the main factor affecting its overall performance.

Summary

Seamless steel pipes and seamed steel pipes have their own advantages and disadvantages. The selection of appropriate steel pipes needs to be determined according to the specific use environment and technical requirements. If the project needs to withstand high pressure, corrosion resistance or work in a high temperature environment for a long time, seamless steel pipes are undoubtedly a better choice. For the transportation of low-pressure fluids or some structural uses, seamed steel pipes become an economical solution because of their price advantage. Understanding their differences can help us make more informed choices in practical applications and ensure the safety and economic benefits of the project.

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