Seamless steel pipe is a kind of round, square and rectangular steel with hollow cross section and no seams around it. Seamless steel pipe is made of steel ingot or solid tube blank by piercing, and then hot rolling, cold rolling or cold drawing. Seamless steel pipe has a hollow cross section and is widely used as a pipeline for conveying fluids. Compared with solid steel such as round steel, the steel pipe is lighter in weight when the bending and torsion strength are the same. It is an economical cross-section steel, and is widely used to manufacture structural parts and mechanical parts, such as steel scaffolding for oil drills.

Development history of seamless steel pipe

Seamless steel pipe production has a history of nearly 100 years. The German Mannisman brothers first invented the two-roll cross-rolling piercer in 1885, the periodic pipe mill in 1891, and the automatic pipe mill (also known as the plug-type pipe mill) invented by Swiss R.C.Stiefel in 1903. Later, various extension machines such as continuous pipe mill and pipe jacking machine appeared, and the modern seamless steel pipe industry began to form. In 1930s, the variety and quality of steel pipes were improved due to the adoption of three-roll pipe mill, extruder and periodic cold rolling mill. In 1960s, due to the improvement of continuous pipe mill and the appearance of three-roll piercer, especially the success of tension reducing mill and continuous casting billet, the production efficiency was improved and the competition ability between seamless pipe and welded pipe was enhanced. In 1970s, seamless pipe and welded pipe kept pace, and the world steel pipe output increased by more than 5% every year. China attached great importance to the development of seamless steel pipe industry after 1953, and has initially formed a production system for rolling various large, medium and small pipes. Generally, copper tubes also adopt the processes of billet oblique rolling and piercing, tube rolling by tube rolling machine and coil stretching.

Application and classification of seamless steel pipe

Usage: Seamless steel pipe is a kind of economic section steel, which plays an important role in the national economy and is widely used in petroleum, chemical industry, boilers, power stations, ships, machinery manufacturing, automobiles, aviation, aerospace, energy, geology, construction and military industry.

Classification:

① According to section shape: circular section pipe and irregular section pipe ② According to material: carbon steel pipe, alloy steel pipe, stainless steel pipe and composite pipe ③ According to connection mode: threaded connection pipe ④ According to production mode: hot-rolled (extrusion, jacking and expansion) pipe, cold-rolled (drawing) pipe ⑤ According to use: boiler pipe, oil well pipe, pipeline pipe, structural pipe and fertilizer pipe.