Manufacturing process of thick-walled steel pipes and seamless steel pipes:

Hot rolled (extruded seamless steel pipe) round tube blank → heating → piercing → three-roll cross rolling, continuous rolling or extrusion → detubing → sizing (or diameter reduction) and cooling → straightening → hydraulic test (or flaw detection) Logo → Warehouse.

The raw material for rolling seamless pipes is round tube blanks. And sent to the furnace for heating via conveyor belt. The billet is fed into the heating furnace for heating, and the temperature is about 1200°C. The fuel is hydrogen or acetylene. Furnace temperature control is a critical issue. After the round tube blank is released from the furnace, it is punched using a pressure punching machine.

Generally speaking, the more common piercing machine is the cone roller piercing machine. This kind of piercing machine has high production efficiency, good product quality, large hole diameter expansion, and can pierce a variety of steel types. After piercing, the round tube billet is sequentially rolled by three-roll cross rolling, continuous rolling or extrusion rolling. After extrusion, the pipe is removed for sizing. The sizing machine rotates a tapered drill bit at high speed into the steel blank to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter length of the sizing machine drill bit. The sized steel pipe enters the cooling tower and is cooled by spraying water. After cooling, the steel pipe is straightened. The straightened steel pipe is sent to the metal flaw detector (or hydraulic test) by a conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. Steel pipes should be strictly selected by dedicated personnel after quality inspection. After the steel pipe passes the inspection, it should be painted with serial number, specification, production batch number, etc. And use a crane to lift it into the warehouse.

Hot-rolled seamless steel pipe: Compared with cold rolling, cold rolling is rolling below the recrystallization temperature, while hot rolling is rolling above the recrystallization temperature. Hot rolling can destroy the casting structure of the steel ingot, refine the grains of the steel, and eliminate defects in the microstructure, thereby making the steel dense and improving its mechanical properties. This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic to a certain extent; bubbles, cracks and looseness formed during pouring can also be welded under the action of high temperature and pressure.