Introduction of seamless pipe

Seamless pipe /tubing (SMLS) is a metal pipe used to transport fluids and gases. It has the characteristics of smooth inner and outer walls, precise dimensions, strong pressure-bearing capacity, and good corrosion resistance. Seamless pipes are made from solid round tube blanks, which are heated and pushed and pulled onto a mold until the round steel is perforated to form a hollow tube. Seamless tubes undergo various finishing operations such as straightening, inspection, hydrostatic testing and imaging. Seamless pipes are widely used in pressure piping, construction, petrochemical and oil refineries. Seamless pipes are processed through production processes such as hot rolling, cold rolling and cold drawing.

Types of seamless pipes:

According to different uses, seamless pipes can be divided into several types: structural seamless pipes, seamless pipes for fluids, seamless pipes for oil and gas, and alloy pipes. Among them, seamless pipes for fluids are the most widely used type.

Seamless pipe specifications and steel grades:

Seamless pipe is available in the following specifications: ASTM A53, ASTM A106, ASTM A252, ASTM A333, ASTM A335, ASTM A501, ASTM A523, ASTM A589, API 5L and API 5CT. The most common seamless pipe is A106B.End finishes for seamless pipe include beveled or square-cut flat ends. Seamless carbon steel pipes are available in black, bare, galvanized or epoxy coated.

Seamless pipe production process:
There are three main production processes for seamless pipes: hot rolling, cold rolling and cold drawing. The hot rolling process is suitable for the production of large-diameter pipes, and the surface of the processed pipes is rough; the cold-rolling process is suitable for the production of small and medium-diameter pipes, and the processed pipes have smooth surfaces and accurate dimensions; the cold-drawing process is suitable for precision pipes and ultra-fine pipes Production, the processed pipes have smooth internal and external surfaces and precise dimensions.

The weight calculation formula of seamless pipe:

The weight of seamless steel pipe per meter is W=0.02466*S(D-S).
Symbol meaning: D=outer diameter, S=wall thickness.

For example, for a seamless steel pipe with an outer diameter of 60mm and a wall thickness of 4mm, find the weight per meter.
Solution: Weight per square meter = 0.02466*4*(60-4)=5.52Kg.

The theoretical weight calculation formula of seamless steel pipe is W=0.0246615(D-S)*SW.

Performance characteristics of seamless pipes:
Seamless pipes have the characteristics of high pressure resistance, corrosion resistance, high temperature resistance, high strength and good sealing. At the same time, seamless pipes have smooth internal and external surfaces, fine inner cavities, accurate dimensions, and strong tensile and bending resistance. They play an important role in transporting fluids and gases. In addition, due to its excellent performance characteristics, seamless pipes have been widely used in the field of environmental protection.

Application scope of seamless pipe:

Seamless pipes have a wide range of applications and are widely used in petroleum, chemical industry, natural gas, metallurgy, electric power, transportation, aviation, aerospace and other fields. Among them, the petroleum and chemical industries occupy the main market for seamless pipes.

Seamless VS Welded pipe

Seamless pipes are made of round billets by hot rolling, cold rolling or cold drawing, and the pipe body has no joints. Welded pipes are manufactured from flat steel plates with welds on the pipe body. Including ERW pipe, LSAW pipe, SSAW pipe. The difference between seamless pipe and welded pipe in raw materials, manufacturing process, performance, appearance, size, application, cost price, etc.

Seamless pipe:
API 5L and ASTM seamless steel pipes are made from steel ingots or solid tubes, passed through perforated tubes, which can then be formed by hot rolling, cold rolling or cold drawing. Hot-rolled seamless steel pipes are made by billet forging, piercing, rolling, shaping and other processes. For large diameter pipes, thick-walled seamless pipes usually adopt this method. Cold-drawn seamless pipe adopts cold-drawn forming technology. The material strength is relatively low, and the exterior and interior control surfaces are smooth. Small-diameter thin-walled seamless pipes are usually made by this method. Seamless steel pipes are rolled from carbon structural steel, low alloy structural steel or alloy structural steel and stainless steel. Seamless steel pipes are used in different industries: line pipes in pipelines, thermal services, machinery industry, chemical industry and other industries.

Welded pipe:
API 5L or ASTM welded pipe includes LSAW pipe, SSAW pipe and ERW pipe. These pipes are made of steel strip or steel plate. The manufacturing process first bends the steel plate and then welds it into round, square and other shapes. Welded steel pipes have the characteristics of high production efficiency, low cost and material saving. It has been widely used in aviation, aerospace, energy, electronics, automobile, light industry and other industries. Strong corrosion resistance in acidic environments.

Advantages of seamless pipe:

The reason why most people prefer seamless pipes over welded pipes is that seamless pipes can withstand extremely high pressures without breaking. This is not possible with seams or welded pipes, since solder joints can easily crack under high pressure. In addition, it is very easy to accurately calculate the pressure of seamless pipe. Seamless pipe is also thinner and lighter than welded pipe and has a uniform shape because it is uniformly extruded from an alloy.

Comparison of compressive strength between seamless pipes and welded pipes:
Seamless pipes have better load-bearing capacity and strength than ERW welded pipes. Therefore, it is widely used in high-voltage equipment, thermal power, and boiler industries. Generally speaking, the weld seam of a welded steel pipe is the weak link, and its quality affects the overall performance of the steel pipe.

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