Types of Flanges

Types of Flanges

Flanges are the mechanical components that are used to connect pipes, valves, pumps, etc. Depending upon where they are being used, there are different types of flanges. The choice of flanges depends upon various factors like its corrosion resistance properties, its class (pressure and temperature ratings), its erosion resistance properties, the number of welds required for its attachment, its size, and its cost, etc. Based on all of these factors, the different types of flanges are mentioned below.

1. Welding Neck Flange

It is also known as a weld neck flange. It has a long-tapered hub which is designed to provide mechanical strength. The welding neck flange comes in different sizes and classes with all the common face types including flat, RT, and raised face types. These flanges are designed to withstand high temperature and pressure conditions.

To connect the weld neck flange to a fitting or a pipe, a butt weld/V-weld, also known as groove weld, is used. It provides full weld penetration which makes the weld neck flange suitable for severe operating conditions like sub-zero temperatures, high-pressure systems, high temperatures, etc. The benefits of using welding neck flanges are listed below

•  High cylindrical loading capability.
•  Erosion resistance.
• Minimizes turbulence.
• Resistance to bending moments due to having a long hub.
• Low delta P.
• Stress distribution due to tapered hub.
• Provides space for testing on the weld due to larger diameter.
• Durable and strong
• Low-pressure drops.

Applications of welding neck flanges are:

• High-pressure systems.
• High-temperature systems.
• Fluctuating conditions

 

2. Slip-on Flange

The slip-on flanges are also known as hubbed flanges. It is a flat plate having a bore size larger than the pipe it is connecting to. This helps the flange to slip over the pipe easily. These flanges are connected to the pipe by either one or two fillet welds, one on the inside of the flange and one on the outside of the flange. These are slip-on flanges that come in many sizes and are used for low-pressure conditions.

The benefits of slip-on flanges are mentioned below.

• It reduces weight and saves space
• Prevent leakage with good sealing performance.
• Requires a small amount of pressure to compress the sealing surface.
•  Cost-effective
• Flexibility
• No welding preparation is required.
• Minimize pipe cutting accuracy.
• Minimize skills required for making the weld.

Applications of slip-on flanges:

• Low-pressure systems.
• Water distribution.
• Heating and cooling systems.
• Piping systems in commercial and industrial settings.

 

3. Socket Weld Flanges

The socket weld flanges contain the socket through which a pipe is inserted and secured by only one fillet weld. The socket weld connection gives high strength to the joint. It allows proper alignment while installation. Due to the low-integrity joint, this type of flanges are only suitable for low to medium classes. These types of flanges are specifically designed for small nominal pipes ranging from the size of four inches to ten inches.  These are commonly used for pipes of half or two inches in size. The socket flanges are used in high-pressure conditions or in pipelines carrying corrosive liquids.

 

 

The benefits of socket weld flanges include:

• Simple design
• Properly applicable for small-sized pipes.
•  Applicable for non-hazardous systems
• Minimize the risk of leakage.
• Prevent penetration of outside welding on the inside of a pipe.

Applications of socket weld flanges

• Oil and Gas
• Boiler and pressure vessels.
• Metallurgy
• Chemical industries
• Shipbuilding
• Engineering

 

4. Lap Joint Flanges

The Lap joint flanges are used when there is frequent disassembly required. These types of flanges have a stub end. The connection of this type of flange is established by first connecting the stub end to the pipe by welding, and then the flange is connected to the stub end with the bolts. The lap joint flanges come in different sizes and are made up of different materials. This type of flanges are designed in a way that it normally has a smooth surface with a flat face, but when they are connected to the stub end, the sealing face is raised. This happens because the flange’s bolting plane is below the sealing face of the stub end.

 

 

The benefits of lap joint flange are:

• Ideal flange for the systems that need frequent disassembly.
• It is available in many different pipe diameters.
• It can be rotated and adjusted to align with the pipe.
• It is a good choice for use in corrosive conditions.
• Inexpensive.

Applications of lap joint flanges:

• Piping systems that need frequent inspection or routine maintenance.
• Low-pressure systems.
• Oil and Gas industry
• Petrochemical industry
• Chemical industry

5. Threaded Flanges

The threaded flanges are also known as screwed flanges. It has threads that are used to connect the flange to the pipe. The male thread is present on the pipe while the female thread is present on the flange. The male and female threads are then connected with the screws. The threaded flange comes in many different sizes with different pressure ratings. This type of flanges are mostly used for pipes under the size of four inches. These flanges are used for low pressure systems, non-toxic systems, and low temperature systems.

The benefits of threaded flanges are mentioned below.

• Wide range of sizes
• Customization options.
• High-quality materials and grades.
• Can be used in explosive areas like flammable liquid storage, petrol pumps, and hexane plants.
• Quick and easier to assemble and disassemble.

Applications of threaded flanges:

• Low-pressure systems.
•  Water and Gas pipelines.
• Chemical plants
• Petrochemical plants.
• Power generation systems.
• Shipbuilding and Maritime systems.
• Flammable liquid storage syatems
• Petrol pumps
• Hexane plants.

 

6. Blind Flange

The blind flanges are also known as closure plate flanges. The main purpose of blind flanges is to terminate a piping system. It is designed to stop the flow and hence, it does not contain the central bore. The blind flange is used for isolating a valve, pipe, or pressure vessel. It is available in different sizes and different classes. They may use the joint face of raised, flat, or ring-type.

 

The benefits of Blind Flanges are:

• Enhanced safety
• Easy to install.
• Easy Maintenance.
• Flexibility.
• Prevent leakage
• Requires minimal welding

Applications of blind flanges

• Termination of pipe system
•  Testing pipe pressure
•  Temporary sealing of a piping system.
• Modifying or repairing pipeline.
• Isolation of pipe, pressure vessel, or valve.
• Pipe engineering
• Petrochemical industries.
• Maintain pressure

The information on all the discussed flange types are mentioned in the following table.

Type of Flange	Weld	ASME Standards	ASME Class	Faces	Joint Integrity	NPS (inch)
Welding Neck flanges	One butt weld	B16.5, B31.3	All	All	High	All
Slip-on flanges	One or Two butt weld	B16.5 B31.3	Generally ≤ 600	FF, RF	Medium	Many
Socket Weld flanges	One fillet weld	B16.5 B31.3	≤ 600	FF, RF	Medium	Generally ≤  to 2 Max≤ 4
Lap Joint Ring  flanges	None	B16.5 B31.3	NA	FF	Na	Not used for small sizes
Stub end of Lap Joint flanges	One butt weld	B16.9 B31.3	150 to 2500	FF, RF, RTJ	High	Not used for small sizes
Threaded flanges	None	B1.20.1 B31.3	≤ 300	FF, RF	Low	Generally ≤  to 2 Max≤ 4
Blind flanges	None	B16.5 B31.3	All	All	Na	All

 

 

Conclusion

The flanges are an important part of forming a pipeline. Choosing the right flange is a very crucial step for preparing a pipe system. Depending upon the conditions and environment of the area where the flanges are to be fitted, there are different types of flanges.

Different flanges have different advantages and applications as mentioned above. Based on your requirements you can make the perfect choice of flanges.

Some flanges can withstand harsh environments whereas some can work with small pipe systems. Some require welding whereas some flanges minimize the welding need. Some are a little expensive whereas some are very cost-effective. So, buy the best match for you.

Need further help? contact a reputable flange manufacturer in Texas region and get a friendly quote!