Carbon steel flanges play an essential role in piping systems, connecting pipes, valves, pumps, and other equipment to create a secure and leak-proof system. Known for their strength, durability, and cost-effectiveness, carbon steel flanges are widely used across various industries, including oil and gas, chemical, power generation, and more.
This guide will explore the different types of carbon steel flanges, their specifications, and the applications or uses they offer, helping you gain a better understanding of their importance in industrial operations.
Carbon steel flanges are a type of flange made from carbon steel, offering features like corrosion resistance, durability, and a smooth finish. They come in different types, each suited to specific applications. For example, carbon steel blind flanges are commonly used to close the end of a pipe.
Carbon steel flanges and end flange connectors are typically made from carbon steel. Some common standards for these include ASTM A694, ASTM A105N (SA105N), MSS SP-44, and DIN 2533. They are available with pressure ratings ranging from class 150 to 2500.
Carbon steel is a type of steel that contains up to 2.1% carbon by weight. According to AISI, it doesn’t require a minimum amount of alloying elements like chromium, molybdenum, nickel, titanium, or vanadium. The copper content must be below 0.04%, and the maximum limits for manganese and silicon are 1.65% and 0.06%, respectively.
As the carbon content increases, the steel becomes harder and stronger after heat treatment. However, this also makes it less flexible. Without heat treatment, higher carbon content can reduce the steel’s ability to be welded. While not used as stainless steel, carbon steel may sometimes include alloy elements.
Functions of Carbon Steel Flanges
Forged flanges are commonly used in low-pressure applications. They have lower carbon content than cast flanges and are nonmagnetic. These flanges are lightweight with a flat design, yet they offer strong mechanical properties. However, if not forged properly, the material can develop uneven or coarse grains. Forged flanges are also harder to strengthen compared to cast flanges, which can be prone to cracking.
In the production of carbon steel flanges, the forging process plays a key role in ensuring that the sealing gasket functions correctly. This is vital for the proper performance of the flange. Forged flanges are made from high-quality materials and provide good insulation, protecting the carbon steel flange from corrosion and environmental damage. Their durable design and corrosion resistance make them highly effective in various applications.
Mild Steel or Low Carbon Steel Pipe Flanges
Carbon steel pipe flanges are often made from mild steel or low carbon steel, which contains a small amount of carbon. This makes the material strong and tough, though it is not easily tempered.
Low carbon steel: Contains 0.005% to 0.3% carbon.
Medium carbon steel: Contains 0.3% to 0.8% carbon.
High carbon steel: Contains 0.8% to 2.0% carbon.
Ultra-high carbon steel: Contains 1.25% to 2.0% carbon.
ASTM A105N (SA105N) Carbon Steel Pipe Flanges
ASTM A105 is a widely used material for forged carbon steel flanges, made from mild carbon steel. It is suitable for both ambient and high-temperature services in pressure systems. This material is known for its durability, cost-effectiveness, and resistance to breaking. When used in stainless steel piping systems, it requires a lap joint end ring to ensure compatibility.
Chemical Composition of A105 Carbon Steel Pipe Flanges
| Element | Composition,% |
| Carbon (C) | 0.35max |
| Manganese (Mn) | 0.60–1.05 |
| Phosphorus (P) | 0.035max |
| Sulfur (S) | 0.040max |
| Silicon (Si) | 0.10–0.35 |
| Copper (Cu) | 0.40max |
| Nickel (Ni) | 0.40max |
| Chromium (Cr) | 0.30max |
| Molybdenum (Mo) | 0.12max |
| Vanadium (V) | 0.08max |
Mechanical Properties of ASTM A105
| Mechanical Properties | Requirements |
| Tensile strength,min,psi [MPa] | 70000 [485] |
| Yield strength,min,psi [MPa] | 36000 [250] |
| Elongation, min, % | 30 |
| Reductionofarea,min,% | 30 |
| Hardness,HB,max | 187 |
Manufacturing Types and Standards of Carbon Steel Flanges
Carbon steel flanges can be produced through either forging or casting methods.
Differences Between Forged Steel Flanges and Cast Iron Flanges
Cost: The forging process is generally more expensive than casting.
Complexity: Cast iron can be shaped to fit complex designs, while forged steel flanges have limitations in design.
Grain Structure: Forging does not produce large or uneven grains.
Application: Cast iron flanges are typically used in non-pressure pipelines, while forged steel flanges are suitable for high-pressure applications.
Precision: A centrifugal machine can create high-precision cast iron flanges compared to standard cast flanges.
Strength: Forged steel is easier to cut and has higher tensile strength.
Performance: Overall, forged steel flanges outperform cast iron flanges due to better shape and lower carbon content, which reduces rusting.
Referred Standards
B16.5: Dimensional standard for steel pipe flanges and fittings.
B16.34: Standards for valves connected by flanges, threaded, and welded ends.
B16.47: Standards for large diameter steel flanges.
SP44: Standard for steel pipeline flanges.
API 605: Standards for large diameter carbon steel flanges.
Coating Type
To protect carbon steel flanges from rust and corrosion, several coatings can be applied:
Anti-rust paint
Oil varnish.
Electric zinc coating (available in white and yellow zinc)
Alloy coating (lined or clad)
Carbon Steel Flange Types
Weld Neck Flange
Slip On Flange
Blind Flange
Socket Weld Flange
Threaded Flange
Reducing Flanges
Carbon Steel Flanges Grades
Carbon steel flanges are classified into several grades, including ASTM A516, A694, A350, A182, and A105. Carbon content in these flanges typically ranges between 1% and 2%. Higher carbon content increases the stiffness and strength of the steel while decreasing its ductility. Furthermore, high carbon levels might make welding more difficult if the steel is not heat-treated.
Carbon Steel A105 Flanges
Carbon steel A105 flanges are forged components used in pressure systems that include fittings, flanges, and valves, especially at high temperatures. They can function efficiently at temperatures ranging from 0 to 550 degrees Fahrenheit. These flanges are ideal for marine and hydrocarbon engineering operations and are widely used in the gas, oil, nuclear power, pump manufacturing, and petrochemical industries.
Carbon Steel A350 LF2 Low-Temperature Flanges
Carbon steel A350 LF2 flanges are intended for low-temperature applications. They are constructed from forged fittings, low-alloy steel forged valves, and ring-rolled carbon flanges. These flanges are renowned for their pressure resistance, strength, and longevity. They have good machinability when forged and hardened, moderate strength, and are in high demand because to their hardness.
Carbon Steel Low Alloy A182 Flanges
The A182 grade is applied to stainless steel pipe valves, flanges, and other high-temperature applications. These flanges are ideal for applications requiring low corrosion and a slow wear rate. They are widely employed in several industries, including petroleum, paper, and chemicals. Their extended lifespan and low maintenance requirements make them a reliable choice, particularly in the paper industry. Buying from a reputed supplier, such as Texas Flanges, ensures increased durability.
Carbon Steel A694 Flanges
A694 flanges are intended for high-stress applications, specifically high-pressure oil and gas transmission. The steel produced must be able to withstand cryogenic and high temperatures. An increase in carbon content, combined with heat treatment, reduces ductility. Without heat treatment, the steel’s weldability may be affected.
Uses of Carbon Steel Flanges
Carbon steel is an alloy primarily composed of iron and carbon. Only three extra elements are permitted in pure carbon steel: manganese (up to 1.65%), silicon (up to 0.60%), and copper (up to 0.60%). Carbon steel flanges harden and strengthen as their carbon concentration increases. However, increasing carbon content might diminish the flanges’ melting point and temperature tolerance, making welding more difficult due to decreased robustness and ductility.
Carbon steel flanges are commonly used in the following applications:
Piping Systems: Water, oil, and gas pipelines require the connection of pipes, valves, and other equipment.
Pressure Vessels: Used in the oil and gas, chemical processing, and power generation industries.
Marine Engineering: Suitable for applications in tough marine settings.
Manufacturing Equipment: Pump manufacturers, petrochemical plants, and nuclear power facilities all use it.
Carbon steel flanges are vital components in many industrial settings due to their strength and adaptability.
Conclusion
Carbon steel flanges are essential components in a variety of industrial applications, providing strength, durability, and versatility. With grades such as ASTM A105, A350, A694, and A182, each flange type is tailored to specific needs, such as high-pressure systems, low-temperature applications, or corrosion resistance. Understanding the qualities and applications of carbon steel flanges enables industry to make informed decisions about their pipes and equipment requirements.
As previously discussed, the production technique, whether forging or casting, influences performance, cost, and application applicability. Furthermore, the appropriate coatings and standards ensure that these flanges can endure the demands of their environments. Businesses can improve the reliability and efficiency of their systems by using high-quality carbon steel flanges from reputable suppliers such as Newzel Industries, a leading supplier in India, resulting in better performance and longevity.
