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What Are Different Grades of Carbon Steel Flanges?

Iron and carbon steel are the main components behind the manufacturing of carbon steel flanges and end flange connectors. These flanges help connect pipes to valves, pressure vessels, pumps, or other equipment. Grades of steel products change depending on the material ratio, such as the carbon content. Many grades of carbon steel flanges e.g. ASTM A105, ASTM A182, ASTM A694, ASTM A516, and ASTM A350 are available. The content of the carbon range is about 1% to 2.1% in weight in the carbon steel flanges.

The increase of carbon element content makes the steel sturdier and stiffer after the heat treatment, and it also becomes less ductile. Without the heat treatment, higher carbon will reduce weldability.

Carbon steel A105 flanges

The Carbon Steel A105 flanges are the forged carbon steel piping components that you can use for valves, flanges, and fittings in pressure systems at higher temperatures and ambient service conditions. You can reliably operate Carbon Steel A105 flanges under temperatures from 0 degrees to 550 degrees. They are helpful in hydro-carbon and marine engineering processes. You can also use it in nuclear power plants, oil and gas equipment, valves manufacturing, petrochemical plants, pumps manufacturing, and heat exchangers. There are many kinds of flanges like blind flanges, weld neck flanges, plate flanges, and much more.

Carbon steel A350 LF2 low-temperature flanges

The Carbon Steel A350 LF2 Flanges encompass many ring-rolled and carbon flanges, valves, low-alloy steel forged, and forged fittings for low temperatures. The flanges are extensively known for their durability, strength, pressure resistance, and temperature rating. The Carbon Steel A350 LF2 Flanges provide maximum machinability when hardened, forged, or normalized. It ends up gaining moderate strength and offers a leakage-proof connection at lower costs. These flanges are usually more in demand than conventional austenitic stainless due to their property of higher hardness versus cost.

Carbon steel in low alloy A182 Flanges

The grade of carbon steel flanges are helpful in stainless steel pipe flanges, forged fittings, valves, rolled alloy, and other high-temperature services. The Carbon Steel low chrome A182 Flanges are one of the outcomes of the ideal selection for low corrosion applications. These flanges do not get worn out as quickly. The use is widespread, especially in the paper, chemical, and petroleum industries. The features of this flange type make it the most reliable product that stays long and does not require repairing soon after the installation. If purchased from the right place, you can ensure the durability of this product.

Carbon steel A694 flanges for high yield service

It is the most stress-reliant carbon steel flange material in comparison to the above three. It is stringent to the high-pressure fluid transmission of gas and oil piping. Most of the property is steel-grade for high-yield service. Manufacturers need to develop well-built steel to withstand both high and cryogenic temperatures. With the increase in carbon content, the steel gets heavy after the heat treatment. It also becomes less ductile. If there is a lack of heat treatment, the chances become higher for carbon to reduce the ability to weld.

About forged steel flanges

There are many ways you can manufacture flanges, the most prominent ones being casting and forging. Flanges are basically a plate-like round device affixed at the end of the fitting, valve, pipe, etc which helps to put a piping system together. Manufacturers develop flanges of many materials that match the material that you use for pipes and fittings. There are usually two ways: Forged carbon steel and cast iron for older, less critical applications.

Forged steel is the excellent mechanical property of almost any flange product. The process of manufacturing happens with carbon steel, alloy steel, or stainless steel. The raw materials are beaten and cut into shape via hammers and presses, which helps to get rid of defects and blocks. A flange helps connect pipes to each other, often with an attachment of a valve to the pipe end. It is functional for the flange on inlets and outlets.

General grades of carbon steel flanges

Below are few common grades of carbon steel flange:

ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70 high yield

ASTM A350 LF1, LF2 CL1/CL2, LF3 CL1/CL2 low temp

ASTM A105N (SA105N) forged

ASTM A516 Grades 55, 60, and 70 plate

How to prevent carbon steel flange from rust?

Carbon steel can get rust, but you can prevent it using the following solutions:

1. Oil varnishing: It helps to lubricate the carbon steel. Oil forms a protective barrier against rust and allows them to move with friction.

2. Anti-rust painting: Painting a carbon steel flange helps to cover metal components in a protective layer. It helps to prevent moisture from reaching the metal and therefore prevents rust and general corrosion.

3. Electric zinc-coated (Yellow or white zinc): Galvanising or electric zinc-coating is one method to prevent rust. It is easy to stop the reach of water and oxygen underneath the metal by coating it in a thin layer of zinc.


It is always better to get in-depth knowledge about the product you are willing to buy. You can find different grades of carbon steel flanges mentioned above from us. The guide will help to select the right one as per the requirement.

If you want any specific flange information, get in touch with us today!

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