Manufacturing Process of Seamless Steel Pipe (Hot rolled and Cold rolled)

Generally, the production process of seamless steel pipes includes two types: hot rolling and cold drawing.
1. 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. Hot-rolled steel pipes are delivered in hot-rolled state or heat-treated state.

The production process of hot-rolled seamless steel pipe: tube blank → heating → piercing → three-roll cross rolling, continuous rolling → pipe stripping → sizing → cooling → straightening → hydraulic test → marking → storage.

The raw material for rolling seamless pipes is round pipe blanks. The round pipe 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 tube blank is fed into the furnace and heated to approximately 1200 degrees Celsius. The heating tube billet fuel is hydrogen or acetylene. The temperature control in the furnace is a key issue. After the tube is out of the furnace, it must be pierced by a piercing machine.

Generally, the more common piercing machine is a tapered roller piercing steel pipe piercing machine. This piercing machine has high production efficiency, good product quality, large perforation diameter expansion, and can penetrate a variety of steel types. After piercing, the tube blank is cross-rolled by three rolls and continuously rolled. After squeezing, take off the tube for sizing. The sizing machine uses a tapered drill bit 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 outer diameter of the sizing machine drill bit). 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 the steel pipe is straightened, it is sent by the conveyor belt to the metal flaw detector for internal flaw detection. If there are cracks or bubbles inside the steel pipe, it will be detected. After the quality inspection, the steel pipes must pass strict manual selection. 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.

2. Cold 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, and other steel pipes, as well as carbon thin-walled steel pipes, alloy thin-walled steel pipes, and stainless steel pipes. Rusty thin-walled steel pipe, special-shaped steel pipe. Cold rolled and delivered in heat-treated condition.

The production process of cold rolled seamless steel pipe: tube blank → heating → perforation → heading → annealing → pickling → oiling → multi-pass cold drawing → blank tube → heat treatment → straightening → hydraulic test → marking → storage.

The rolling method of cold drawn seamless steel pipe is more complicated than that of hot rolling, and the first three steps of their production process are basically the same. The difference starts from the fourth step. After the round tube blank is emptied, it needs to be headed and annealed. After annealing, use a special acid liquid for pickling. After pickling, apply oil. Then it is followed by multiple cold drawing. After heat treatment, it is straightened. After the steel pipe is straightened, it is sent by the conveyor belt to the metal flaw detector for internal flaw detection. If there are cracks in the steel pipe, the problem of bubbles and the like will also be picked out.

From the outside, the length of cold drawn seamless pipe is generally shorter than that of hot rolled seamless pipe. In terms of wall thickness, cold-rolled seamless pipes are more uniform than hot-rolled seamless pipes, hot-rolled pipes have lower accuracy and rough surface, while cold-rolled pipes have higher precision, better surface roughness and higher prices.

Tips:ASTM A53 Gr.B is the grade in ERW high frequency welded pipe, divided into A and B grades. ASTM A53 ERW pipe is a typical carbon steel pipe. It is largely used to convey fluids at low / medium pressures such as oil, gas, steam, water, air and also for mechanical applications.