Application of seamless steel pipe in mechanical steel structure

The machinery industry is a major consumer of steel pipes, mainly including oil, cylinder tubes, tubes for hydraulic parts, tubes for shafts, shafts and rolls, and gas and liquid tubes for mechanical equipment. Seamless steel pipe account for 4% of the steel used in the machinery industry. %, so the amount of steel pipe used in the machinery industry in 2017 was estimated to be 6 million tons.

In 2017, China's shipbuilding completion volume may be the same as in 2016, and the hand-held order volume will be less than 90 million DWT. For a 10,000-ton ship, the total length of steel pipes is about tens of kilometers. The marine pipes are mostly water supply and drainage, steam, fuel oil, hydraulic oil pipes, etc. The steel pipe types include seamless steel pipes, straight seam submerged arc welded pipes and high-frequency straight seam welded pipes. The pressure is at least 0.7MPa, the highest is 40MPa, the design temperature is 60°C~300°C, and the pipe diameter is ф114mm~ф610mm. It is estimated that the amount of steel pipes for ships in 2017 will be around 600,000 tons.

Automobiles and engineering machinery cabs are mostly made of P-section cold-formed steel as the frame. At present, the square rectangular tube for automobile axles in China has a wall thickness of 16 mm. When cold-formed steel is formed by cold bending, when the wall thickness is greater than 14 mm, the rounded corners are prone to cracks. Therefore, the user generally commissions a seamless steel pipe factory to produce such cold-formed steel. The hot-rolled seamless square rectangular tube developed and produced by Baotou Steel Seamless Steel Tube Plant is suitable for square rectangular tubes for automobile axles. Its specifications are 150mm×160mm×16mm, the material is Q345B, the yield strength is ≥345MPa, and the tensile strength is ≥510MPa. Elongation ≥ 21.0%, round corner requirement 30 ° ~ 40 °, average hardness 153HBW, to meet user requirements. The hot-rolled seamless square rectangular tube developed by Panzhihua Steel Seamless Steel Tube Plant has a thickness of up to 18mm and a maximum specification of 300mm×300mm.