What Are the 6 Common Types of Flanges?

When considering flanges, you might ask: how many types of flanges are there? There are 6 primary types of flanges, each tailored to specific applications and needs. These include the Blind Flange, Slip On Flange, Lap Joint Flange, Weld Neck Flange, Socket Weld Flange, Threaded Flange, and Long Weld Neck Flange. 

Each serves a distinct purpose depending on the pressure, environment, and maintenance requirements of the system.

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Discover the 6 Types of Flanges in Piping Systems

Blind Flange

A Blind Flange is a unique type used to seal off the end of a piping system or a pressure vessel. Unlike other flanges, it doesn’t have a bore for the pipe to pass through. This design makes it ideal for applications where you must block off the flow or close a section of the piping system.

Key Features:

• Solid and lacks any opening, preventing the passage of fluids.
• Provides easy access for maintenance and inspection.
• Suitable for high-pressure environments.

Common Uses:

• Used in applications where future piping extensions are planned.
• Installed at the ends of pressure vessels to ensure they are sealed.

Blind flanges are most commonly found in systems where maintenance is essential. They allow for easy access to the piping or equipment without dismantling the entire setup.

Slip On Flange

The Slip-On Flange is one of the most widely used flanges. It is typically utilized because of its ease of installation and affordability. This flange is designed to slide over the pipe and is then welded in place, both internally and externally. The idea for this is to secure the connection.

Key Features:

• Simple design, easy to install.
• Requires two welds for full sealing: one on the inside and one on the outside.
• Less expensive than most other types of flanges.

Common Uses:

• Low-pressure systems where the sealing efficiency isn’t a primary concern.
• Ideal for cooling water lines, low-pressure gas lines, and firefighting systems.

Though slip-on flanges are more cost-effective, they are not recommended for high-pressure or high-temperature environments. These situations would require stronger connections.

Lap Joint Flange

The Lap Joint Flange is typically used with a stub end. This component allows the flange to be loose and rotate freely around the pipe. The stub end also provides flexibility during installation and alignment. It becomes highly effective in systems where frequent disassembly is necessary.

Key Features:

• Allows for easy alignment due to its rotational capability.
• Typically used in systems where space constraints are a concern.
• Less material cost since the flange is not welded directly to the pipe.

Common Uses:

• Piping systems are prone to corrosion, like offshore platforms and marine environments.
• Systems where parts of the piping need to be frequently removed for inspection or cleaning.

This flange type is favored for its convenience in assembly and disassembly. It is even a popular choice in industries with fluctuating demands and piping adjustments.

Weld Neck Flange

A Weld Neck Flange is designed for high-pressure systems where stress and load factors are significant. Its long, tapered hub reinforces the flange’s strength. 

Additionally, it ensures a secure connection with the pipe. The gradual transition from flange to pipe reduces stress concentration, making it highly reliable in demanding applications.

Key Features:

• Tapered neck allows for better stress distribution.
• Strong weld connection ensures minimal risk of leakage.
• Suitable for high-pressure and high-temperature applications.

Common Uses:

• Power generation, oil and gas refineries, and high-stress chemical plants.
• Systems that handle highly corrosive or hazardous materials.

Due to its robust design, the weld neck flange is the preferred choice for critical applications requiring durability and long-lasting performance.

Socket Weld Flange

The Socket Weld Flange features a recessed area that allows the pipe to be inserted before welding. This provides a smooth bore leading to reduced flow restrictions. This quality makes it a good option for small-diameter, high-pressure piping systems.

Key Features:

• Allows for a secure and precise pipe alignment before welding.
• Reduces turbulence and flow restriction.
• Can handle higher pressure than the slip-on flange.

Common Use:

• High-pressure pipelines, chemical injection lines, and steam systems.

Despite being reliable for high-pressure applications, socket weld flanges are typically limited to smaller piping systems. They typically accommodate systems usually up to 2 inches in diameter

Threaded Flange

The Threaded Flange is a special type of flange that has internal threads. The flange is designed to be screwed directly onto a pipe without the need for welding. This makes it perfect for low-pressure systems or when welding is not possible or desirable. A good example would be highly flammable environments.

Key Features:

• Screws onto the pipe instead of being welded.
• Ideal for areas where welding is unsafe.
• Easy installation and removal.

Common Uses:

• Low-pressure piping, water, and air lines 
• Systems transporting flammable substances.

While threaded flanges are convenient for certain applications, they are not suitable for high-pressure or high-temperature environments. The reason behind this is due to their lower mechanical strength compared to welded flanges.

Common Materials for Manufacturing Types of Flanges

The types of pipe flanges are manufactured from various materials, depending on the application and operating conditions:

1. Carbon Steel: Used in low to moderate temperature and pressure applications.
2. Stainless Steel: Preferred for corrosive environments due to its high resistance to corrosion and chemical attack.
3. Alloy Steel: Suitable for high-temperature, high-pressure applications.
4. Nickel Alloys: Ideal for environments exposed to extreme temperatures and aggressive chemicals.

The choice of material is crucial to ensure durability, resistance to corrosion, and the overall safety of the piping system.

Flanges Advantages that Make Them Unique from Others

• Flexibility: Flanges make it easy to assemble and disassemble pipe systems for maintenance, repairs, or modifications.
• Strength: Welded flanges provide strong, leak-proof connections, particularly in high-pressure systems.
• Versatility: The various types of flanges in piping systems allow for customization based on pressure, temperature, and material compatibility.
• Safety: Flanges create reliable seals, minimizing the risk of leaks, even in high-pressure or hazardous environments.

Which Flange Type Should You Choose

When choosing the right flange type for your piping system, several factors should be considered to ensure optimal performance and longevity.

One of the most important factors is pressure and temperature. For high-pressure systems, more robust flanges like the weld neck flange or Long Weld Neck Flange are necessary. they can withstand greater stress and provide better sealing in extreme conditions.

Another important consideration is ease of maintenance. In applications where frequent disassembly is required, such as for cleaning or inspections, a lap joint flange is ideal. Its design allows for easy rotation and alignment, making assembly and disassembly simpler and quicker.

Cost is also a crucial factor, especially for projects with budget constraints. For low-pressure systems where high-strength connections are not essential, the slip-on flange or threaded flange may be appropriate. These flanges are easier to install and more economical.

Conclusion

In conclusion, the 6 common types of flanges in piping systems offer unique advantages and are designed to meet specific requirements, from low-pressure water lines to high-pressure chemical plants. Whether you’re selecting a flange for its durability, ease of installation, or cost-effectiveness, the right choice can greatly impact the performance and longevity of your piping system.

If you’re looking for high-quality flanges that meet all your industrial needs, Longan Flange is a trusted manufacturer. They have been in the industry for years offering a wide range of ANSI-compliant flanges. With a commitment to precision and durability, Longan Flange provides reliable solutions that stand the test of time.

References:

Types of Flanges (1)

Pipe Flanges Selection Guide (2)