Seamless Steel Pipe Process Flow And Specific Classification

Now the process flow is briefly introduced as follows:

1. Hot rolling (extruded seamless steel pipe): round tube blank → heating → perforation → three-roll cross rolling, continuous rolling or extrusion → detuning → sizing (or diameter reduction) → cooling → straightening → hydraulic test (or flaw detection) → Mark → Warehousing The raw material for rolling seamless pipes is round tube billet. The round tube embryo must be cut by a cutting machine into a billet with a length of about 1 meter and sent to the furnace via a conveyor belt for heating. It is fed into the furnace for heating, and the temperature is about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Temperature control in the furnace is a key issue. After the round tube comes out of the furnace, it must be pierced through a pressure punching machine. The more common piercing machine is the tapered roller piercing machine. This kind of piercing machine has high production efficiency, good product quality, large piercing diameter expansion, and can pierce a variety of steel types. After piercing, the round tube blank is successively rolled by three-roll cross rolling, continuous rolling, or extrusion before being extruded. The pipe sizing machine uses a conical drill bit to rotate at high speed into the steel blank to drill holes 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. After the steel pipe is sized, it enters the cooling tower and is cooled by spraying water. After cooling, the steel pipe will be straightened and sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles, and other problems inside the steel pipe, they will be detected after the steel pipe quality inspection. After passing the strict quality inspection of hand-selected steel pipes, the serial numbers, specifications, production batch numbers, etc. are sprayed with paint and then lifted into the warehouse by a crane:

2. Cold drawn (rolled) seamless steel pipe: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening →Hydraulic test (flaw detection)→Marking→The rolling method of cold-drawn (rolled) seamless steel pipes into storage is more complicated than hot-rolled (extruded seamless steel pipes). The first three steps of their production process are basically the same. The differences start from the first three steps. The four steps begin. After the round tube is hollowed out, it needs to be headed. After annealing, it needs to be pickled with a special acidic liquid. After pickling, oiling is followed by multiple passes of cold drawing (cold rolling). After special heat treatment, the steel pipe will be straightened. After straightening, the steel pipe will be sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles, and other problems inside the steel pipe, the quality of the steel pipe will be detected. After the inspection, the steel pipes must pass strict quality inspection by hand, then the serial number, specification, production batch number, etc. with paint, and then lifted into the warehouse by a crane.

Seamless steel pipes are divided into the following varieties due to their different uses:

①GB/T8162-1999 (seamless steel pipe for structural use) is mainly used for general structures and mechanical structures. Its representative materials (grades): carbon steel, 20, 45 steel; alloy steel Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc.

②GB/T8163-1999 is mainly used in engineering and large-scale equipment to transport fluid pipelines. The representative materials (grades) are 20, Q345, etc.

③GB3087-1999 (seamless steel pipe for low and medium-pressure boilers) is mainly used for industrial boilers and domestic boilers to transport low and medium-pressure fluids. The representative materials are No. 10 and No. 20 steel.

④GB5310-1995 (seamless steel pipe for high-pressure boilers) is mainly used for high-temperature and high-pressure resistant conveying fluid headers and pipes in power stations and nuclear power plant boilers. Representative materials are 20G, 12Cr1MoVG, 15CrMoG, etc.

⑤GB5312-1999 (carbon steel and carbon-manganese steel seamless steel pipes for ships) are mainly used for grade I and II pressure-resistant pipes for ship boilers and superheaters. Representative materials are 360, 410, and 460 steel grades, etc.

⑥GB6479-2000 (seamless steel pipe for high-pressure fertilizer equipment) is mainly used for conveying high-temperature and high-pressure fluid pipes on fertilizer equipment. Representative materials of pipes are 20, 16Mn, 12CrMo, 12Cr2Mo, etc.

⑦GB9948-1988 (seamless steel pipe for petroleum cracking) is mainly used in boilers, heat exchangers, and fluid transport pipelines in petroleum smelting plants. Its representative materials are 20, 12CrMo, 1Cr5Mo, 1Cr19Ni11Nb, etc.

⑧GB18248-2000 (seamless steel pipe for gas cylinders) is mainly used to make various gas and hydraulic gas cylinders. Its representative materials are 37Mn, 34Mn2V, 35CrMo, etc. In addition, there is also GB/T17396-1998 (hot-rolled seamless steel pipe for hydraulic props). steel pipe), GB3093-1986 (high-pressure seamless steel pipe for diesel engines), GB/T3639-1983 (cold-drawn or cold-rolled precision seamless steel pipe), GB/T3094-1986 (cold-drawn seamless steel pipe, special-shaped steel pipe), GB/T8713 -1988 (Precision inner diameter seamless steel pipe for hydraulic and pneumatic cylinders), GB13296-1991 (Stainless steel seamless steel pipe for boilers and heat exchangers), GB/T14975-1994 (Stainless steel seamless steel pipe for structural use), GB/T14976-1994 ( Stainless steel seamless steel pipes for fluid transportation) GB/T5035-1993 (seamless steel pipes for automotive half-shaft casings), APISPEC5CT-1999 (casing and oil pipe specifications), etc.