Seamless steel pipe is a round, square or rectangular steel with a hollow section and no joints on the periphery. Seamless steel pipes are made of steel ingots or solid tube billets through perforation into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. Seamless steel pipes have a hollow section and are mostly used as pipelines for conveying fluids. Compared with solid steel such as round steel, steel pipes have the same bending and torsion strength and lighter weight. They are economical cross-section steels and are widely used in manufacturing structural parts and mechanical parts, such as steel scaffolding for oil drills.
The production of seamless steel pipes has a history of nearly 100 years.
The German Manismann brothers first invented the two-roll cross-rolling piercing machine in 1885, and invented the periodic tube rolling machine in 1891. In 1903, the Swiss R Stiefel (RCStiefel) invented the automatic tube rolling machine, and various extension machines such as continuous pipe rolling mills and pipe jacking machines appeared in the future, and the modern seamless steel pipe industry began to form.
In the 1930s, due to the adoption of a three-roll tube rolling mill, an extruder, and a periodic cold rolling tube mill, the variety and quality of steel pipes were improved. In the 1960s, due to the improvement of the continuous tube mill, the emergence of the three-roll piercing machine, especially the success of the application of the tension reducer and the continuous casting billet, improved production efficiency and enhanced the ability of seamless pipes to compete with welded pipes. In the 1970s, seamless pipes and welded pipes went hand in hand, and the world's steel pipe output increased at a rate of more than 5% per year.
After 1953, China attached great importance to the development of seamless steel pipe industry, and has initially formed a production system for rolling various large, medium and small pipes. Copper pipes generally also use ingot skew piercing, tube rolling, and coil drawing processes.
Seamless steel pipe is a kind of economic cross-section steel, which has a very important position in the national economy. It is widely used in petroleum, chemical industry, boilers, power stations, ships, machinery manufacturing, automobiles, aviation, aerospace, energy, geology, Various departments such as construction and military industry.
①According to the section shape: round section tube, special-shaped section tube
②According to material: carbon steel pipe, alloy steel pipe, stainless steel pipe, composite pipe
③According to the connection mode: threaded connection pipe, welded pipe
④According to the production method: hot rolled (extruded, topped, expanded) tube, cold rolled (drawn) tube
⑤According to purpose: boiler pipe, oil well pipe, line pipe, structural pipe, fertilizer pipe
①Main production process of hot-rolled seamless steel pipe:
Tube billet preparation and inspection → tube billet heating → perforation → tube rolling → waste tube reheating → fixed (reduced) diameter → heat treatment → finished tube straightening → finishing → inspection (non-destructive, physical and chemical, bench inspection) → storage
②Main production process of cold-rolled seamless steel pipe:
Blank preparation → pickling and lubrication → cold rolling (drawing) → heat treatment → straightening → finishing → inspection