Hot rolled seamless steel pipe

Hot-rolled seamless steel pipe is a common steel pipe product, usually used for transporting fluids, gases, structural purposes, etc. It is made by heating steel billets to high temperatures and then rolling them continuously in a rolling mill, so it has a seamless appearance and excellent mechanical properties. This process provides greater strength and durability and is suitable for a variety of environments and industrial areas. Hot-rolled seamless steel pipes are widely used in petroleum, natural gas, chemical industry, shipbuilding, nuclear power, construction, machinery manufacturing and other fields. Hot rolling is relative to cold rolling. Cold rolling is rolling below the recrystallization temperature, while hot rolling is rolling above the recrystallization temperature.

Hot rolled seamless steel pipe production process flow

The production process of hot-rolled seamless steel pipes includes several basic processes such as billet preparation before rolling, pipe billet heating, piercing, rolling, fixed diameter reduction, steel pipe cooling, and finishing. There are generally three main deformation processes in the production of hot-rolled seamless steel pipes today: perforation, pipe rolling and diameter reduction.

Perforation: turning a solid tube blank into a hollow capillary tube; we can understand it as shaping, that is, setting the cross section of the rolled piece into a circular shape; the equipment is called a piercing machine. The requirements for the perforation process are: firstly, the wall thickness of the pierced capillary tube must be uniform, the ovality is small, and the geometric size accuracy is high; secondly, the internal and external surfaces of the capillary tube must be smooth, and there must be no scars, folds, cracks and other defects; thirdly, The third is to have corresponding piercing speed and rolling cycle to adapt to the production rhythm of the entire unit, so that the final rolling temperature of the capillary tube can meet the requirements of the pipe rolling machine.

Pipe rolling: turning a thick-walled capillary tube into a thin-walled (close to the wall thickness of the finished product) waste tube; we can regard it as a fixed wall, that is, determine the wall thickness value of the waste tube in this process based on the subsequent process diameter reduction and empirical formulas ;This equipment is called a pipe rolling machine. The requirements for the pipe rolling process are: first, when turning thick-walled capillary pipes into thin-walled raw pipes (wall reduction extension), first of all, the raw pipes must have high wall thickness uniformity; secondly, the raw pipes must have good internal and external surface quality.

Fixed diameter reduction (including tension and reduction): a large circle becomes a small circle, referred to as sizing; the corresponding equipment is a fixed (reducing) diameter machine, its main function is to eliminate the uneven outer diameter of the raw pipe caused by the previous process of rolling ( The same pipe or batch) to improve the outer diameter accuracy and roundness of hot-rolled finished pipes. The requirements for the fixed diameter reduction process are: first, to achieve the purpose of sizing under a certain total diameter reduction rate and a smaller single frame diameter reduction rate; second, to achieve the production of multiple specifications of finished pipes using one specification of tube blank. Task, and thirdly, the outer surface quality of the steel pipe can be further improved.

The standard for seamless steel pipes is ASTM 252. The main national standards for hot-rolled seamless steel pipes are GB/T8162-2018 "Seamless Steel Pipes for Structural Use" and GB/T8163-2018 "Seamless Steel Pipes for Liquid Transport". These national standards are for hot-rolled seamless steel pipes. The standardized production and quality control of steel pipes play an important guiding role, ensuring that the quality of seamless steel pipes is reliable and suitable for different engineering projects and application scenarios.

Advantages of hot rolled seamless pipes

1. High-strength hot-rolled seamless pipe has high strength and hardness and can withstand large pressure and tension. In various industrial fields, it is often necessary to withstand high pressure and high temperature conditions, and hot-rolled seamless pipes can meet these requirements.

2. Good corrosion resistance Hot-rolled seamless pipe has good corrosion resistance and can resist the erosion of various acids, alkalis, salts and other chemical substances. This makes them widely used in fields such as chemical industry, oil and gas.

3. Good processing performance Hot-rolled seamless pipe has good processing performance and can be processed and formed in various ways, such as cold bending, hot bending, welding, etc. This makes them very convenient when manufacturing parts of various complex shapes.

4. Good surface quality: The hot-rolled seamless pipe has a high surface finish, no obvious oxide scale and defects, and can meet high requirements for appearance and surface quality.

Uses of hot rolled seamless pipes

1. Oil and natural gas industry hot-rolled seamless pipes are widely used in oil and natural gas exploration, production, transportation and storage. They can be used in oil well casing, oil pipes, natural gas pipelines, etc., and can withstand harsh conditions such as high pressure, high temperature and corrosion.

2. Chemical industry hot-rolled seamless pipes are used for pipes and equipment in the chemical industry. They can be used to transport various chemicals, such as acids, alkalis, salts, etc., and have good corrosion resistance.

3. Electric power industry hot-rolled seamless pipes are used in boilers, heat exchangers, condensers and other equipment in the electric power industry. They can be used to transport high-temperature and high-pressure steam and hot water, and have excellent pressure resistance.

4. Mechanical industry hot-rolled seamless pipes are used in various parts and structures in the machinery industry. They can be used to manufacture automobile parts, engineering machinery, ships, railway vehicles, etc., with good strength and toughness.

5. Construction Industry Hot-rolled seamless pipes are used in structures and equipment in the construction industry. They can be used for building supports, frames, stair handrails, etc., with excellent load-bearing capacity and earthquake resistance.

Hot-rolled seamless pipes have a wide range of uses and advantages and are suitable for oil, natural gas, chemical, electric power, machinery, construction, coal and other industries. They have the characteristics of high strength, corrosion resistance, good processing performance, good surface quality and long service life, and are indispensable and important materials in all walks of life.