Seamless steel tube is a round, square, rectangular steel with a hollow section and no seams around it.Seamless steel tubes are made of ingots or solid billets perforated into capillary tubes and then  hot rolled, cold rolled or cold drawn.

Seamless steel pipe with hollow section, a large number of pipes used for conveying fluids, In the bending and torsion strength at the same time,Comparing steel pipe with round steel and other solid steel.steel pipe weight is light, is a kind of economic section of steel, widely used in the manufacture of structural parts and mechanical parts, such as oil drilling steel scaffolding.

Seamless steel tube production has a history of nearly 100 years.The German Manismann brothers first invented the two-roll cross-rolling punch in 1885, then invented the periodic pipe rolling machine in 1891, and the Swiss R.C.Stiefel invented the automatic pipe rolling machine (also known as the top pipe rolling machine) in 1903, and various extension machines, such as the continuous pipe rolling machine and the pipe pushing machine, began to form the modern seamless steel tube industry.In the 1930s, the three-roll pipe mill was adopted.

Extrusion press and periodic cold rolling mill improve the variety and quality of steel tubes.In the 1960s, due to the improvement of continuous rolling pipe mill, the emergence of three-roll punch, especially the success of the application of tension reducing machine and continuous casting billet, has improved the production efficiency and enhanced the competitiveness of seamless pipe and welded pipe.

In the 1970s, seamless pipe and welded pipe are keeping pace with each other, and the world steel pipe output is increasing by more than 5% per year.Since 1953, China has attached great importance to the development of seamless steel tube industry, and has initially formed a production system for rolling various large, medium and small pipes.In general, the copper pipe also adopts the process of billet cross rolling and perforation, pipe mill rolling and coil drawing.

Application and classification of seamless steel tubes

Application: Seamless steel tube is a kind of economic section steel, has a very important position in the national economy, widely used in petroleum, chemical industry, boiler, power station, ship, machinery manufacturing, automobile, aviation, aerospace, energy, geology, construction and military sectors.

Classification:

(1) According to the shape of section divided into: circular section tube, special-shaped section tube

(2) according to the material: carbon steel pipe, alloy steel pipe, stainless steel pipe, composite pipe

(3) According to the connection mode: threaded connection pipe, welding pipe

(4) According to the production mode: hot rolling (extrusion, top, expansion) pipe, cold rolling (pull) pipe

(5) According to the use: boiler pipe, oil well pipe, pipeline pipe, structural pipe, fertilizer pipe.

Seamless steel tube production process

Main production process of hot-rolled seamless steel tube  (main inspection process) :

Preparation and inspection of pipe billet → heating of pipe billet → perforating → rolling pipe → reheating of empty pipe → fixing (reducing) diameter → heat treatment → straightening of finished pipe → finishing → inspection (nondestructive, physical and chemical, station inspection) → warehousing

(2) Cold rolling (drawing) seamless steel pipe production process

Billet preparation → pickling and lubrication → cold rolling (drawing) → heat treatment → straightening → finishing → inspection

The production process flow chart of hot-rolled seamless steel tube is as follows: