Difference between seamless steel pipe and ordinary steel pipe

Seamless steel pipe is generally through an annular slit molten state and then by stretching out the backlog of processing molding process, so there is no seam. In performance, especially compared with ordinary steel has greatly improved the bearing capacity, it is often being used for high-voltage equipment.

Seamless steel pipe is made of a single piece of metal and has no jointed steel pipe on the surface, which is called seamless steel pipe. According to the production method, the hot rolled tube, the cold rolled tube, the cold drawn tube, the extruded tube, the top tube and the like are seamlessly divided. According to the cross-sectional shape, the seamless steel tube is divided into two types: round and irregular, and the special-shaped tube has a variety of complex shapes such as square, oval, triangular, hexagonal, melon-shaped, star-shaped and finned tubes. The maximum diameter is 650mm and the minimum diameter is 0.3mm. According to different uses, there are thick-walled tubes and thin-walled tubes. Seamless steel tubes are mainly used as petroleum geological drilling tubes, cracking tubes for petrochemical industries, boiler tubes, bearing tubes, and high-precision structural steel tubes for automobiles, tractors, and aviation. Seamless steel pipe is widely used. General purpose seamless steel tubes are rolled from ordinary carbon structural steels, low alloy structural steels or alloy structural steels with the highest yield, and are mainly used as pipes or structural parts for conveying fluids. .

Depending on the use of three different types of supply: a, according to chemical composition and mechanical properties of the supply; b, according to the mechanical performance of the supply; c, according to the water pressure test supply. Pipes supplied by Types a and b, if used to withstand liquid pressure, are also subject to hydrostatic testing.

The special-purpose seamless pipes include seamless pipes for boilers, chemical power, seamless pipes for geological use and seamless pipes for petroleum.

Seamless steel tubes have a hollow cross-section and are used in large quantities as pipes for transporting fluids, such as pipes for transporting oil, natural gas, gas, water, and certain solid materials. Compared with solid steel such as round steel, steel pipes have a lighter weight when subjected to the same flexural and torsional strength and are economical cross-section steels.

Widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile drive shaft, bicycle frame and steel scaffold used in construction, etc. The manufacture of ring-shaped parts using steel pipes can improve the material utilization, simplify the manufacturing process, save materials and processing Working hours have been extensively manufactured with steel pipes.

Seamless steel pipe has no longitudinal weld seam. The manufacturing of seamless steel pipe requires a mechanism to force the hole into the billet.
Rotary piercing and rolling is the most common method for producing seamless steel pipe today. The process starts with a conditioned steel round bar, which is heated, pierced, and worked. The bar is made to flow around a piercer point in order to form a hollow billet. The interior of the pipe is supported with a mandrel or a plug while the billet roller is elongated. Sizing of the steel pipe is achieved by additional rolling on the outside diameter.
Seamless steel pipe has 20% higher ASME (American Society of Mechanical Engineers) working pressures compared to welded steel pipe of the same material and size due to having no welded seam. The welded and drawn steel pipe can also have a visible seam that may concern end users.
Another advantage of seamless steel pipe is that it can offer superior corrosion resistance because it has little potential for impurities. Using seamless steel pipe allows you to avoid the potential for defects and differences in malleability that may be associated with the welded area in welded pipes. Unlike welded pipes, seamless pipes do not require testing for weld integrity.

Therefore, seamless steel pipe is often more suitable for critical applications.

Hydraulic equipment such as piping connections. Ordinary steel weld parts of its weaknesses, weld quality is also a major factor in its overall performance impact. People who lived in the north generally have had water pipes or heating pipes burst in the winter cold experience explosive place are generally weld not seamless steel pipe.

Ordinary steel pipe, such as water pipes, is generally flat plate by bending and welded together after that you can find a seam in the above; and the seam of large diameter spiral weld is generally thicker.

Seamless pipe Specification, standard and identification

Seamless pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. Seamless pipes dominates 65% of market share in Chinese boiler industry.