Thin-walled seamless steel pipes are made of steel ingots or solid tube blanks through perforation to make capillary tubes, and then hot-rolled, cold-rolled or cold-rolled.
The raw material of thin-walled seamless steel pipes is round tube blanks. The round tube blanks are cut by a cutting machine into a billet with a length of about 1 meter and sent to the furnace for heating via a conveyor belt. The billet is fed into the furnace and heated at a temperature of approximately 1200 degrees Celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is a key issue. After the round tube is out of the furnace, it must be pierced through a pressure punching machine. Generally, the more common piercing machine is the tapered roller piercing machine. This type of piercing machine has high production efficiency, good product quality, large perforation diameter expansion, and can wear a variety of steel types. After piercing, the round tube billet is successively cross-rolled, continuous rolled or extruded by three rolls. After squeezing, take off the tube and calibrate. The sizing machine uses a tapered drill to rotate at a high speed into the steel blank to punch holes to form a steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the drill bit of the sizing machine. After the steel pipe is sized, it enters the cooling tower and is cooled by spraying water. After the steel pipe is cooled, it will be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles, etc. inside the steel pipe, it will be detected. After the quality inspection of steel pipes, strict manual selection is required. After the quality inspection of the steel pipe, paint the serial number, specification, production batch number, etc. with paint. It is hoisted into the warehouse by a crane.
Specifications: The specifications of seamless steel pipes are expressed in millimeters of outer diameter * wall thickness.
Classification of thin-walled seamless steel pipes
Seamless steel pipes are divided into two types: hot-rolled and cold-rolled (dial) seamless steel pipes
Hot-rolled seamless steel pipes are divided into general steel pipes, low- and medium-pressure boiler steel pipes, high-pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.
Cold-rolled (dial) seamless steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, as well as carbon thin-walled steel pipes, alloy thin-walled steel pipes, Stainless thin-walled steel pipes, special-shaped steel pipes. The outer diameter of hot-rolled seamless pipe is generally greater than 32mm and the wall thickness is 2.5-75mm. The diameter of cold-rolled seamless pipe can be up to 6mm and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipe can be up to 5mm and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
Generally use seamless steel pipes: generally use seamless steel pipes to ensure the strength and flattening test. Hot-rolled steel pipes are delivered in hot-rolled state or heat-treated state; cold-rolled steel pipes are delivered in heat-treated state.
Seamless steel pipes for low and medium pressure boilers: used to manufacture various low and medium pressure boilers, superheated steam pipes, boiling water pipes, water wall pipes and superheated steam pipes for locomotive boilers, large smoke pipes, small smoke pipes and arched brick pipes. Use high-quality carbon structural steel hot-rolled or cold-rolled (dial) seamless steel pipe.
High-pressure boiler steel pipes: high-quality carbon structural steel, alloy structural steel and stainless heat-resistant steel seamless steel pipes mainly used to manufacture high-pressure and above steam boiler pipes. These boiler pipes are often working under high temperature and high pressure. The pipe will also be oxidized and corroded under the action of high-temperature flue gas and water vapor. Therefore, the steel pipe is required to have high durability, high oxidation resistance, and good structural stability.
Seamless steel pipes for geological drilling and oil drilling: use drilling rigs to drill wells for the exploration of underground rock structure, groundwater, oil, natural gas and mineral resources. Petroleum and natural gas exploration is even more inseparable from well drilling. Seamless steel pipes for geological drilling are the main drilling equipment, including core outer pipes, core inner pipes, casing pipes, and drill pipes. Because drilling pipes need to be deep into the formation depth of several kilometers, the working conditions are extremely complicated. The drill pipe is subjected to stresses such as tension, compression, bending, torsion, and uneven impact load, and is also subject to mud and rock wear. Therefore, pipe materials are required It must have sufficient strength, hardness, wear resistance and impact toughness.
Petroleum cracking pipes: seamless pipes for furnace pipes, heat exchanger pipes and pipelines used in petroleum refineries. In addition to the certified chemical composition and various mechanical properties of the steel pipe, it is also necessary to ensure the water pressure, flattening, flaring and other tests, as well as surface quality and non-destructive inspection. The steel pipe is delivered under heat treatment.
Stainless steel pipe: Hot-rolled and cold-rolled stainless steel pipes of various stainless steels are widely used in petroleum and chemical equipment pipelines and stainless steel structural parts for various purposes. In addition to ensuring chemical composition and mechanical properties, they are used as steel pipes that can withstand fluid pressure. To ensure that the water pressure test is qualified. All kinds of special steel pipes must be guaranteed according to the stipulated conditions.
Process flow of thin-walled seamless steel pipe
Process flow of sanitary mirror tube:
Tube blank → inspection → peeling → inspection → heating → perforation → pickling → grinding → lubrication and air drying → welding head → cold drawing → solution treatment → pickling → pickling passivation → inspection → cold rolling → degreasing → cutting head →Air-drying→Inner polishing→Outer polishing→Inspection→Marking→Packaging of finished products