Introduzione
Tubi in acciaio al carbonio stand as one of the main components of various industries, while you can find multiple types of carbon steel pipes in the market. Mainly made of carbon and iron, with minor quantities of other materials. The carbon content is 2.1% of the total alloy’s weight.
Variations in steel pipes arise from differences in chemical composition, manufacturing methods, and classification standards. These variations impact performance, longevity, and suitability for specific applications.
That’s why understanding the fundamental aspects of carbon steel pipe material and the classification system that helps define their specific uses and standards is critical. It will be helpful for engineers, fabricators, and business owners to make an informed decision in the industrial context.
What is Carbon Steel Pipe?
Carbon steel (CS) pipes or round tubes are composed primarily of carbon and iron. This is the cornerstone for their remarkable strength and ability to withstand pressure. These steel pipes also contain small amounts of other materials. These include manganese, phosphorus, copper, and silicon, and help enhance the mechanical properties.
Primarily, the carbon content in carbon steel pipes ranges from 0.02% to 2.1% of the alloy’s total weight. When iron and carbon combine, their atoms form a microstructure composed of phases. The specific arrangement depends on the iron’s carbon content and its thermal history. Therefore, properties vary depending on the amount of carbon added during manufacturing. Also, they can be altered through heat-treatment processes such as quenching, annealing, and normalizing. These Properties include wall thickness, tensile strength, and hardness.
More carbon increases strength and hardness but can reduce the pipe’s flexibility and weldability. In comparison, low carbon content means lower strength.
Because of their cost-effectiveness, carbon steel pipes are widely used in the industry. These range from small automotive parts to extensive structural supports.
Tipi di tubi in acciaio al carbonio
There are different types of carbon steel pipes classified according to two main categories:
- the amount of carbon content
- the manufacturing method.
These are designed under specific conditions that yield an optimal balance of mechanical properties for specific applications. Let’s discuss these types in detail.
Classification by Carbon Content
- Low-Carbon Steel Pipes
In low-carbon steel pipes (also known as mild steel), the carbon content ranges from 0.05% to 0.25%. They are commonly used pipes in various applications due to their toughness and ductility. Besides, they are hot- or cold-worked and can be easily formed and welded. Yet, due to their relatively low carbon content, they exhibit lower strength.
Common low-carbon steel grade pipes used in manufacturing include: Q235, ASTM A36, ASTM A53, ASTM A106, #20 steel, AISI 1020, S235, and C22E.
They are mainly used in applications such as automobile parts, structural support, and low-pressure fluid applications.
- Medium-Carbon Steel Pipes
The carbon content of medium-carbon steel pipes ranges from 0.31% to 0.6%. They offer high strength and hardness. However, they possess comparatively low toughness and ductility; yet, their mechanical properties can be enhanced through quenching and heat treatment.
Some examples of steel grades used in medium-carbon steel include #45 Steel, AISI 1045, and C45E. Their applications include construction projects and automotive and mechanical parts, such as shafts, frames, and exhaust systems.
- High-Carbon Steel Pipes
These high-carbon steel pipes have a carbon content of 0.6% to 2.11%. They are very high-strength pipes with low ductility and toughness. Additionally, they cannot be welded easily. For the welding process, these pipes must undergo a detailed heat-treatment program that is integrated into the welding process.
Frequently used grades of high-carbon steel include #65 Steel, 65Mn, AISI 1065, T8 and T8A, T10 and T10A, AISI W1 and W2, C60E, and C80U. They are common in cutting tools, springs, and heavy-duty machinery parts.
Classification by Manufacturing Method
Carbon Steel Seamless Pipes
Seamless pipes are produced without welded joints, typically by piercing a solid steel billet and forming it through hot or cold rolling. This process yields pipes with consistent strength and enhanced resistance to pressure and temperature fluctuations.
- Hot-rolled carbon steel pipes: These involve heating. In this method, the steel billet is heated to about 1000°C, then rolled into the desired pipe shape. This method ensures uniformity and durability in the final product. The resulting outer diameter of these pipes exceeds 32mm, while the wall thickness ranges from 2.5mm to 75mm. These pipes are used for low-pressure-to-high-pressure steel piping.
- Cold-rolled carbon steel pipes: These pipes are made by gradually reducing the thickness and width of the steel through a series of rollers at room temperature or slightly elevated temperatures. After cold rolling, the steel undergoes annealing. This softens it and eliminates internal stresses caused by the rolling. The final steps include shaping the steel to the required dimensions. That’s why it is trimmed of excess material and polished to achieve a smooth finish. This process ensures the steel has the desired size, form, and appearance. This method results in high-dimensional accuracy. Their outer diameter can reach 6mm, while the wall thickness can reach 0.25mm.
Carbon Steel Welded Pipes
These pipes are formed by rolling steel plates or strips and welding the seam. They offer good strength. But it is slightly lower than that of SSAW with the same specifications. Their production cost is not high. They are applicable for low- to medium-pressure settings. They are further divided into two categories depending on their production method, which are as follows:
- Carbon Steel ERW Pipes (Electric Resistance Welded): ERW pipes are made by roll-forming a steel plate and welding the edges using electric resistance welding. These have intricate detailing, a uniform seam, and are economical. Additionally, they are lightweight, precision-engineered, and structured appropriately. They come in different material grades, such as A, B, X42, X52, etc., and, depending on their specifications, can be used in low- to high-pressure applications, including water and gas distribution.
- Carbon Steel LSAW Pipes (Longitudinal Submerged Arc Welded): They are manufactured by bending steel plates longitudinally and welding the seam with submerged arc welding. This results in tough, thick-walled, large-diameter, seamless finish, and rustproof pipes. They are strong, expansive, and used in applications including onshore and offshore oil and gas pipelines. In short, they are applicable when high performance, high tolerance, and strong structural support are required.
Carbon Steel SSAW Pipes (Spiral Submerged Arc Welded)
SSAW pipes are produced by spirally winding steel strips into a tubular shape and then welding the spiral seam to form a solid pipe. They allow for larger-diameter pipes and have high strength. But here the production cost increases slightly. The application includes water and gas transportation, where flexibility in size is important.
Vantaggi del tubo in acciaio al carbonio
Carbon steel pipes, being crucial in various applications, serve various advantages discussed below:
- Firstly, they possess expectation rigidity and strength. That’s why they can withstand high-pressure conditions and heavy loads. For example, they are mainly used in high-performance applications such as structural support, gas and oil pipelines, bridges, and transmission systems.
- They serve as excellent corrosion-resistant components, as they can withstand harsh environments and chemical exposure. However, a protective coating is crucial, as it enhances resistance. That’s why steel pipes can be easily used in marine applications.
- Carbon steel pipes, without a doubt, are good thermal and electrical conductors. Due to these properties, they can be used in power industries.
- Ease of installation is another advantage of carbon steel pipes. They are usually lightweight, making them easy to transport and facilitating efficient installation.
- Additionally, they are cost-effective. The reason for this is the abundance of raw materials and well-established manufacturing. This results in low material and manufacturing costs, leading to its cost-effectiveness.’
- Due to the many types of carbon steel pipes available on the market, they can be used in a wide range of applications. This contributes to their versatility.
- The recyclability of carbon steel pipes can be achieved easily without compromising material integrity. This means they make a good, environmentally friendly,
Industry Standards and Specifications
| Standard | Descrizione | Area di applicazione | Key Features |
| ASTM A53 | Covers black steel pipes, both seamless and welded, with an option of hot zinc coating | Structural support, pipeline | seamless and welded types, weldable |
| ASTM A106 | Specifications for seamless carbon steel pipes are used where high heat is common. | High-temperature pipelines | High strength and heat resistance |
| API 5L | Defines the requirements for line pipes used to transport gas, oil, and water. | Oleodotti e gasdotti | Pressure-resistant, intended for transporting fluids |
| ASME B36.10 | Standardizes dimensions and properties for welded and seamless wrought steel pipes. | Mechanical and structural uses | Defines pipe dimensions and weights |
| DIN 2448 | European guideline for manufacturing and testing seamless steel pipes. | Industrial piping and boiler systems | Covers dimensions and delivery conditions |
| ISO 3183 | Global standard for steel pipes used in petroleum and natural gas pipeline systems. | Pipeline transportation | Specifies manufacturing and testing requirements |
| BS EN 10216 | European standard focusing on seamless steel tubes meant for pressure vessel applications. | Pressure vessels and boilers | Covers mechanical properties and testing |
These standards ensure carbon steel pipes meet quality, safety, and performance requirements for various industries worldwide. Each standard covers pipe dimensions, mechanical properties, manufacturing, and testing protocols to suit specific applications.
Conclusione
To conclude, carbon steel pipes are crucial components in many industrial applications. These include gas and oil transportation, structural support, irrigation systems, and many more. Carbon steel pipes exhibit different mechanical properties depending on the amount of carbon added during manufacturing or heat treatment. They are classified into two different categories. It is based on their carbon content percentage and manufacturing methods, giving you several variations. Understanding the specifications and standards is important. It will help you select the appropriate carbon steel pipe that meets your industrial and civil needs.