Flanges Types, Materials, Applications and Selection

Flanges are an important part of industrial measurement devices such as sensors and flow meters. They offer a reliable and efficient way to connect components and transfer fluids and gases, offering versatility, reliability, and ease of maintenance.

 

What Are Flanges?

Flange, as per Merriam Webster, is defined as a rib or rim for strength, for guiding, or for attachment to another object. It’s a ring-like structure used to connect pipes, valves, pumps, or other equipment in a piping system. Unlike welding or threading, flanges allow for quick assembly, disassembly, and maintenance.

 

Most Common Types of Flanges

• Blind Flange
• Weld Neck Flange
• Slip-On Flange
• Threaded Flange
• Socket Weld Flange
• Lap joint flange

All flange types, except the Lap Joint flange, feature a raised face design.

 

 

Blind Flanges

Blind Flanges are used to seal the end of a piping system. It has no central opening and offers a complete seal.

 

Weld Neck Flanges

 

Weld Neck Flanges are used to minimize stress at the flange base, ideal for high-pressure and high or low temperature environments.

A weld neck flange is best matched with the inner diameter of the pipe to minimize turbulence and erosion caused by flow restriction.

 

Slip-On Flanges

Slip-On Flanges connect pipes by slipping over the pipe’s outer diameter.They are used in confined spaces; requires dual welding (inside and outside).

 

Threaded Flanges

Threaded Flanges, similar to slip-on flanges, provides a connection without welding. The bore is threaded. Therefore, threaded flanges are unsuitable for high-temperature or high-stress conditions. Under cyclic operations, they may fail after several cycles of contraction and expansion.

 

Socket Weld Flanges

Socket Weld Flanges are similar to slip-on flanges, designed for smaller pipelines（½” to 4″）. They ensure a secure connection via welding.

 

Lap Joint Flanges

Lap Joint Flanges are primarily used in carbon or low-alloy steel pipeline systems. They are ideal for pipeline systems that require frequent disassembly for inspection and maintenance.They are often paired with stub ends for flexibility.

 

Flange Materials

Flanges can be made of different materials. Common materials include:

Carbon Steel (A105)

A105 forged carbon steel is one of the most widely used materials for flanges due to its versatility and cost-effectiveness. Common sizes range from 1/2” to 24”. This material is suitable for applications operating in temperatures from ambient up to 1,000°F and pressure levels between 20 to 6,170 psi, making it ideal for a wide range of industrial uses.

Carbon steel, with a carbon content of up to 2.1% by weight, is primarily alloyed with iron and does not contain significant amounts of nickel or chromium. A105 material specifically has a maximum allowable carbon content of 0.35%. As the carbon content increases, the steel’s hardness and strength improve, often achieved through heat treatment techniques such as quenching, tempering, and normalizing.

Although these treatments can make carbon steel slightly less ductile and more brittle, they enhance its performance in high-pressure and high-stress applications, often outweighing the challenges in welding and shaping. The absence of significant trace elements like molybdenum, nickel, and chromium also contributes to its affordability while maintaining durability and reliability in various conditions.

 

316/316L

316 is an austenitic chromium-nickel stainless steel containing molybdenum. The addition of molybdenum enhances overall corrosion resistance, particularly against pitting in chloride ion solutions, and increases strength at elevated temperatures.

316L is the low-carbon version of 316, which minimizes carbide precipitation caused by welding. Common applications include waste manifolds, boiler components, heat exchangers, jet engine parts, pharmaceutical and photographic equipment, valves and trim pumps, chemical processing equipment, stills, storage tanks, evaporators, pulp and paper processing equipment, textile processing equipment, marine environments, and piping components.

316L is widely used in welded components, as it is not susceptible to carbide precipitation from welding, ensuring optimal corrosion resistance.

 

Alloy C-276

One of the few alloys resistant to wet chlorine gas, hypochlorite, and chlorine dioxide solutions. Exhibits excellent resistance to oxidizing salts such as ferric and cupric chlorides. It maintains resistance to grain boundary precipitation in welded conditions, making it suitable for many chemical process applications.

Typical applications include components in chemical and petrochemical processes involving organic chlorides or halides and acid catalyst processes. Other industrial uses include pulp and paper (stills and bleaching areas), scrubbers and flue gas desulfurization ducts, pharmaceutical and food processing equipment.

 

Alloy A-400

Alloy 400 is a nickel-copper alloy known for excellent corrosion resistance in various environments. It offers good overall corrosion resistance, weldability, and high strength. It is widely used in various applications, demonstrating outstanding resistance to fast-flowing brackish water and seawater. It is particularly effective against de-aerated hydrochloric and hydrofluoric acids. Slightly magnetic at room temperature, it finds applications in chemical, petroleum, and marine industries.

 

Duplex Stainless Steel

Duplex stainless steel combines austenitic and ferritic materials, offering high thermal conductivity, superior mechanical strength, and excellent resistance to stress corrosion cracking.

In applications prone to stress corrosion cracking, duplex stainless steel provides a more cost-effective alternative to alloys such as C-276. Due to its high mechanical strength, it offers greater pressure resistance compared to 316SST flanges.

There are many duplex grades, with Duplex 2205 being widely recognized for its versatility. This material is often used in environments where chlorides and acidic gases (H₂S) are prevalent.

 

Flange Standards

Different standards govern flange design, including ASME/ANSI B16.5, EN 1092-1, JIS B2210/B2220, and ISO 7005.

 

How to Select Flanges?

Flange selection depends on compatibility with pressure, temperature, and application-specific requirements. When we offer flanges for our sensors and flow meters, we will carefully consider the specific applications of our customers, allowing for long-term and reliable.

 

Conclusion

Flanges are indispensable components in industrial measurement systems, enabling seamless integration of sensors, flow meters, and other devices into complex piping networks.

By understanding their types, materials, and applications, businesses can ensure reliable performance and ease of maintenance, driving efficiency and safety in their operations. Holykell specializes in providing high-quality sensors and flow meters equipped with industry-standard flange connections, tailored to meet the diverse needs of our clients worldwide.

For more information about flanges or industrial measurement solutions, contact us today!