Flange Types: A Comprehensive Guide and Their Applications

Flanges are essential parts of piping systems. They offer a secure connection between pipes, valves, and equipment for easy inspection, cleaning, or modification. Understanding the different types of flanges in piping is crucial for selecting the right components for specific applications. Flanges are indispensable in industries dealing with oil and gas, chemical processing, and energy production, with various types targeted to meet unique requirements. Effective operation of these systems requires an understanding of the features and functionality of each type of flange.

What is a flange?

A flange is a flat, circular, or ring-like component that joins two parts of a piping system. It is normally bolted into place using precisely aligned bolt holes to ensure a secure connection. These bolt holes are essential for attaching flanges to pipes or equipment, providing a reliable seal with the help of a gasket High-pressure and high-temperature conditions need to be handled.

Thus, flanges are made to withstand them and be stable as well. In addition to their principal purpose of linking pipes and components, flanges are essential for system flexibility, enabling the replacement, expansion, or rerouting of pipelines without major interruptions. The bolt holes on flanges play a crucial role in this flexibility, allowing for easy disassembly and reassembly.

Different Types of Flanges and Their Applications

Weld Neck Flange

Weld Neck Flange Applications

• High-pressure systems at refineries of oil and gas.
• Steam pipelines in power plants.
• Lines for chemical processing are subjected to variations in temperature and pressure.
• Critical piping networks for minimum turbulence and maximum endurance.

Slip-On Flange

Slip-On Flange Applications

• Industrial plant cooling water systems.
• For fire protection systems and sprinkler lines.
• Use for low-pressure process lines manufacturing and HVAC systems.
• Pipelines for which dismantling or realignment is not required frequently.

Socket Weld Flanges

Applications:

• Industrial machinery hydraulic and pneumatic systems.
• Where leakage prevention is critical for chemical and food processing industries.
• Aviation or marine high-pressure fuel lines.
• Systems for carrying non-corrosive or low-corrosive fluids.

Threaded Flange

Applications

• Low-pressure water supply lines within plumbing systems.
• Temporary piping systems for construction or testing.
• Industrial and commercial facilities, air and gas utility services.
• Hazardous environments that are considered dangerous for welding work.

Blind Flange

Blind flanges are solid discs that fit onto the end of a pipe or vessel, providing easy access for an inspection and modification; fluids or gases are prevented from flowing or leaking.

Applications:

• Closing off unused pipeline sections of oil and gas installations.
• In chemical plants, pressure vessels and storage tanks.
• Systems that would require maintenance periodically or that would need to be expanded in the future.
• Applications in high-pressure power generation and petrochemical industries.

Lap Joint Flange

Applications:

• Food processing and pharmaceutical pipework require regular maintenance or cleaning.
• Corrosive or abrasive substances are handled by high-pressure systems.
• Easy realignment required maintenance-intensive pipelines.
• In applications requiring material flexibility, the flange material can be different from the pipe material.

Ring-Type Joint (RTJ) Flanges

Applications:

• High-pressure oil and gas pipelines.
• Petrochemical facilities, offshore drilling rigs.
• Systems involving hazardous or corrosive materials.
• Power generation plants and high-temperature environments.

Long Weld Neck Flanges

Applications:

• In industrial plants, pressure vessels and heat exchangers.
• Boiler manufacturing and maintenance.
• Piping systems of nuclear power plants.
• For applications with connections in confined spaces or hard-to-reach areas.

Key Factors in Choosing the Right Flange

Operating Pressure and Temperature

Flanges should be capable of withstanding the pressure and temperature of the fluid or gas within the system. For example, weld neck or ring-type joint (RTJ) flanges are better in a high-pressure and high-temperature environment, such as in oil refineries or steam pipelines.

A slip-on or threaded flange would be suitable for low-pressure applications. The bolt holes in these flanges are designed to accommodate standard bolts, ensuring a secure and reliable connection. Identify whether the flange is rated for a pressure class with ANSI or ASME standards to prevent failure.

Pipe Size and Material Compatibility

The flange must be the same diameter and wall thickness as the pipe so that it makes a secure connection. Also, flange material should be usable with the pipe and with transported substances in order to avoid corrosion or degradation. For example:

• Because they are stainless steel, these flanges are ideal for corrosive environments.
• The general industrial applications of carbon steel flanges are found to be wide.
• Some specific chemical processes may use non-metallic flanges, like plastic or composite.

Environmental Conditions

Flange selection is largely a function of environmental factors like chemicals, moisture, or extreme temperatures that can affect them. For instance:

• Co-corrosion-resistant materials in coastal or offshore applications require duplex stainless steel.
• Systems in cryogenic environments may require some low temperatures.
• Used in harsh industrial settings, flanges are wear- and abrasion-resistant.

Installation and Maintenance Requirements

When selecting a flange, consideration should be given not only to ease of installation but also to future maintenance requirements. When systems are to be disassembled and assembled fairly frequently, flanges such as lap joints offer convenience. They do not have to be welded to the pipe. Thus, they are easily replaced and adjusted. For more permanently installed and high-pressure applications, a weld neck or socket weld would be preferred for their strength and secure connections.

Cost Considerations

Budget is an important factor when selecting the right frame. There are more economical options, like slip-on flanges for low-stress or non-critical systems, providing an effective solution. However, high-performance, high-pressure, and specialized applications will require higher-priced flanges, such as RTJ or long weld neck flanges, to allow for reliability and safety concerns. It is very important to achieve a balance between cost and what the operation of the system requires for both economic efficiency and long-term durability.

Pressure Ratings and Standards

Pressure Rating	Class (ANSI/ASME)	Typical Applications	Material Compatibility
150	ANSI Class 150	Low-pressure systems	Carbon steel, Stainless steel
300	ANSI Class 300	Medium-pressure systems	Carbon steel, Stainless steel
600	ANSI Class 600	High-pressure systems	Carbon steel, Alloy steel, Stainless steel
900	ANSI Class 900	High-pressure, high-temperature systems	Alloy steel, Stainless steel
900	ANSI Class 900	High-pressure, high-temperature systems	Alloy steel, Stainless steel
1500	ANSI Class 1500	Extreme pressure systems	Stainless steel, Nickel alloys
2500	ANSI Class 2500	Very high-pressure systems	Stainless steel, Nickel alloys
DIN PN6 to PN64	DIN 2501	European standard for pressure systems	Carbon steel, Stainless steel, Alloy steel

YANHAO: Your Trusted Flange Manufacturer

YANHAO is one of the foremost flange manufacturers with high-quality flanges, which provide different types to meet the various demands of industries around the world.

YANHAO guarantees precision engineering and longevity with the use of durable materials for every flange designed to deliver long-lasting performance, reliability, and safety in different applications. YANHAO offers flanges for high-pressure systems and corrosive environments and regular installation according to international standards.

At YANHAO, we offer quality flange solutions where every customer is prioritized and satisfied. For more information about our comprehensive financing, reach out to us.

Bottom Line

The selection of the proper flange ensures the efficiency, safety, and long life of your piping system.

With proper knowledge of the different types of flanges and their applications and taking into account operating pressure, temperature, pipe material compatibility, and environmental conditions, you can maximize your performance.

Also, remember to balance cost with the particular requirements of your project when making a well-informed decision. YANHAO’s range of high-quality flanges and professional advice will help you choose the right flange for your needs.