Types of seamless carbon steel pipes

Types of seamless carbon steel pipes

Carbon steel pipe is a type of seamless pipe used in construction and manufacturing to convey fluids and solids. Although there are many types of carbon steel pipe available, they all share some key characteristics, including strength, hardness, and durability. Types of seamless carbon steel pipe vary by application, each for a specific purpose. This article will explore the different types of seamless carbon steel pipe, their pros and cons, and best practices for using them.

Types of seamless carbon steel pipes
The various types of seamless carbon steel pipes available today can be divided into three main categories: Hot rolled seamless steel pipe (hrs), cold rolled seamless steel pipe (crs) and cold drawn seamless steel pipe (cds). Within each category there are several variants dedicated to specific applications (such as oil or gas transportation) or certain intensities.

Hot rolled seamless tube
The hot-rolled seamless pipe is made from a heated round billet and formed into a cylindrical shape. They are often used in engineering applications requiring higher strength than cold rolled or cds tubes. The heat treatment process makes them extra hard and strong, able to withstand high temperatures and pressures. Advantages of hot-rolled seamless tubes include cost-effectiveness, strong construction, and the ability to customize shapes. Drawbacks include their weight, which can make them difficult to transport and install. Hot rolled seamless pipe is often used for larger projects involving higher pressures and temperatures.

Cold rolled seamless tube
Cold-rolled seamless pipe is made by shaping hot-rolled steel through a series of rolls. Unlike hot rolled steel, cold rolled steel is harder and more brittle. It also allows for more precise machining and shaping, making it ideal for equipment that requires precision. The advantages of cold-rolled tubes include greater resistance to corrosion and wear, better machinability, and lower cost. Disadvantages of cold-rolled pipe include insufficient strength compared to hot-rolled steel, a greater likelihood of cracking, and limited customizability. Cold-rolled tubing is often used in smaller applications that don't require as much strength or precision.

Cold drawn seamless tube
Cold-drawn seamless tubes are made by forcing hot-rolled tubes through one or more dies. This forces the material to become denser, making it stronger. They are ideal for applications where strength and pressure resistance are critical, such as automotive hydraulic lines and tubing. Advantages of cold-drawn seamless tubing include high strength, low cost, and the ability to manufacture precise shapes. Drawbacks include their potential to crack if not properly tempered, lack of flexibility, and limited customizability. Cold drawn seamless tubing is most commonly used in automotive and industrial applications.

General seamless carbon steel pipe: It is made by hot rolling or cold rolling of high-quality carbon steel such as 10, 20, 30, 35, 45, 16mn, 5mnv and other low alloy structural steel or 40cr, 30crmnsi, 45mn2, 40mnb and other alloy steel. 10, 20 and other low carbon steel seamless pipes are mainly used for fluid conveying pipelines. Seamless tubes made of medium carbon steel such as 45 and 40cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Generally, seamless steel pipes are used to ensure strength and flattening tests. Hot-rolled steel pipes are delivered in a hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in a 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 arch brick pipes, etc. Hot-rolled or cold-rolled (dial) seamless steel pipes are made of high-quality carbon structural steel. It is mainly made of no. 10 and no. 20 steel. In addition to ensuring the chemical composition and mechanical properties, hydrostatic tests, crimping, flaring, and flattening tests are required. Hot rolling is delivered in a hot rolled state, and cold rolling (dial) is delivered in a heat treated state.

High-pressure boiler steel pipe: Mainly used to manufacture high-quality carbon structural steel, alloy structural steel and stainless heat-resistant steel seamless steel pipe for steam boiler pipes with high pressure and above pressure. These boiler pipes often work 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 durable strength, high oxidation resistance, and good structural stability. The steel grades used are: High-quality carbon structure steel grades are 20g, 20mng, 25mng; alloy structural steel grades are 15mog, 20mog, 12crmog, 15crmog, 12cr2mog, 12crmovg, 12cr3movsitib, etc.; 1cr18ni9 and 1cr18ni11nb high-pressure boiler tubes are commonly used in rusty heat-resistant steel in addition to ensuring chemical composition and mechanical properties , it is necessary to do hydrostatic test one by one, and to do flaring and flattening tests. Steel pipes are delivered in a heat-treated state. In addition, there are certain requirements for the microstructure, grain size and decarburization layer of the finished steel pipe.

Seamless steel pipes for geological drilling and oil drilling: In order to prove the underground rock structure, groundwater, oil, natural gas and mineral resources, drilling rigs are used to drill wells. The exploitation of oil and natural gas is inseparable from well drilling. The seamless steel pipe for oil drilling used in geological drilling is the main equipment for drilling, mainly including core outer pipe, core inner pipe, casing, drill pipe, etc. Since the drilling pipe has to work deep into the formation depth of several thousand meters, the working conditions are extremely complicated. The drill pipe is subjected to stresses such as tension, compression, bending, torsion and unbalanced impact loads, and is also subject to mud and rock wear. Therefore, pipes are required it must have sufficient strength, hardness, wear resistance and impact toughness. The steel used for steel pipes is represented by "Dz" (geological chinese pinyin prefix) plus a number one to represent the yield point of the steel. The commonly used steel grades are 45mnb and 50mn of dz45; 40mn2, 40mn2si of dz50; 40mn2mo, 40mnvb of dz55; 40mnmob of dz60, 27mnmovb of dz65. Steel pipes are delivered in a heat-treated state.

Petroleum cracking tubes: Seamless tubes for furnace tubes, heat exchanger tubes and pipelines used in petroleum refineries. Commonly used high-quality carbon steel (10, 20), alloy steel (12crmo, 15crmo), heat-resistant steel (12cr2mo, 15cr5mo), stainless steel (1cr18ni9, 1cr18ni9ti) manufacturing. In addition to the 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 testing. Steel pipes are delivered in heat-treated condition. Stainless steel pipes: Hot-rolled and cold-rolled stainless steel pipes of various stainless steels are widely used in petroleum, chemical equipment pipelines and stainless steel structural parts for various purposes. In addition to ensuring chemical composition and mechanical properties, steel pipes used to withstand fluid pressure to ensure that the hydrostatic test is qualified. All kinds of special steel pipes shall be guaranteed according to the regulations.

In conclusion

Seamless carbon steel pipes are widely used in construction and manufacturing. Each type of plumbing serves specific needs and applications, so it's important to understand their pros and cons before using them in a project. Hot-rolled seamless tubes are the most cost-effective and widely used, while cold-rolled and cold-drawn tubes are more precise and provide greater strength and resistance. Regardless of the type of seamless carbon steel pipe chosen, proper installation, handling, and maintenance will ensure the longevity of any project.