Small Diameter Seamless Steel Pipe

Generally, those with an outer diameter of less than 89mm and more than 4mm can be collectively referred to as small-diameter seamless pipes. The main production process of small-diameter hot-rolled seamless steel pipes includes several basic processes such as billet pre-rolling preparation, pipe billet heating, piercing, rolling, fixed diameter reduction, steel pipe cooling, and finishing. Bubbles, cracks and porosity formed during pouring of small-diameter hot-rolled seamless steel pipes can also be welded under high temperature and pressure.

Small-diameter hot-rolled seamless steel pipe: hot rolling is relative to cold rolling, cold rolling is rolling below the recrystallization temperature, and hot rolling is rolling above the recrystallization temperature.

①Main production process of hot-rolled seamless steel pipe (△Main inspection process):
Tube blank preparation and inspection△→tube blank heating→piercing→tube rolling→steel tube reheating→diameter setting (reduction)→heat treatment△→finished tube straightening→finishing→inspection△(non-destructive, physical and chemical, Taiwan inspection)→warehousing

②Main production process of cold-rolled (drawn) seamless steel pipe:
Billet preparation→pickling and lubrication→cold rolling (drawing)→heat treatment→straightening→finishing→inspection

The production process of general seamless steel pipe can be divided into cold drawing and hot rolling. The production process of cold rolling seamless steel pipe is generally more complicated than hot rolling. Sizing test, if the surface does not respond to cracks, the round pipe will be cut by a cutting machine, and cut into a billet with a length of about one meter. Then enter the annealing process. Annealing should be pickled with acidic liquid. When pickling, pay attention to whether there is a large amount of foaming on the surface. If there is a large amount of foaming, it means that the quality of the steel pipe cannot meet the corresponding standards. In appearance, the cold-rolled seamless steel pipe is shorter than the hot-rolled seamless steel pipe. The wall thickness of the cold-rolled seamless steel pipe is generally smaller than that of the hot-rolled seamless steel pipe, but the surface looks brighter than the thick-walled seamless steel pipe. Much rougher, and the caliber does not have too many burrs.

The delivery state of hot-rolled seamless steel pipes is generally delivered after heat treatment in the hot-rolled state. After passing the quality inspection, the hot-rolled seamless steel pipe must be strictly hand-selected by the staff. After the quality inspection, the surface must be oiled, followed by multiple cold-drawing experiments, and the perforation experiment must be carried out after the hot-rolling treatment. , If the perforation diameter is too large, it will be straightened and corrected. After straightening, it is sent to the flaw detector by the transmission device for flaw detection test, and finally it is labeled, arranged in specifications and placed in the warehouse.

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