The 6 Common Types Of Flanges Explained

The 6 Common Types Of Flanges Explained

Flanges are spherical-shaped protruded rims, helpful for attaching two pipes within the piping system. Flanges are highly versatile, making them useful in many industrial applications. They also:

  • Increase the strength of the pipelines.
  • Stabilize and guide the movements of the machines.
  • Enables to assemble and disassemble the pipes.


In industrial premises, especially petrochemical and oil industries, we use pipes to transfer fluids (liquid or gaseous). These fluids might comprise flammable, volatile, or toxic components, which may be hazardous to health. Thus, engineers close these pipelines with the help of the flanges. These flanges enable to:

  • Secure the outer environment of the industry.
  • Maintain the chemical composition of the inner components.


Flanges are available in different shapes and sizes. Depending upon work and operating temperature, one must select the alloy coatings. The material or alloy of flanges should be same as that of piping material. For instance, if the piping coating is Inconel 601 alloy, then the flanges must have Inconel 601 coating.

The following are some common and easily available type of flanges in the market: 

  • Threaded Flanges
  • Socket-Weld Flanges
  • Slip-On Flanges
  • Lap-Joint Flanges
  • Neck-Weld Flanges
  • Blind Flanges


Threaded Flanges (formerly known as screwed flanges) have threads within the bores of the flange. This internal thread enables us to connect the pipelines with matching male threads on the pipes.

Threaded Flanges are easy to install. However, it is not suitable for high-pressure applications. It is available in sizes of NPS 4 or below. Threaded Flanges can be RF (Raised-Face) or FF (Flat Face) and are most helpful in utility services, such as air and water. The cost of these flanges and the fabrication process is economical.


Socket Weld fittings are quite the opposite of threaded flanges. SW Flanges has a female socket in which we fit the pipes. After we insert the pipeline in these flanges, we weld the flanges to create a permanent joint.

Generally, we use SW Flanges in small bore pipings, whose diameter is NPS 4 or smaller. It is suitable for a low-pressure application but provides robust connectivity than threaded flanges. Socket Flanges can be RF (Raised-Face) or FF (Flat Face). The cost of these flanges and the fabrication process is slightly more than that of threaded flanges.


Slip-On Flanges have holes in the outer diameter of the surface, along with a bigger hole in the center. Technically, we design SO Flanges to fit a pipe into the inner gap of the flange. Thus, you find that their inside diameter is greater than the pipe’s outer diameter.

After we insert the pipe inside the SO Flanges, we weld them from both inside and outside. It is suitable in moderate-temperature areas and useful in low-pressure applications. SO Flanges can be RF (Raised-Face) or FF (Flat Face). The cost of these flanges and the fabrication process is reasonable.


In case of frequent assembling or disassembling of the pipeline, we use lap-joint flanges. The lap flanges have two components: a stub end and a loose backing flange. We butt-weld the stub end to the pipe to create a permanent joint, enabling the backing flange to move smoothly.

Often we use carbon steel for the backing flanges to save cost. Lap flange provides better joining and connection flexibility, as we can freely rotate the flanges on the pipe. These flanges are not suitable for small pipes, and their fabrication cost is slightly higher than a socket and threaded fittings.


Weld-Neck is the most common and widely used type of flanges. Weld-Neck Flanges are circular and consist of an extended rim above their surface. We use butt-welding process to connect them with the pipelines, which makes them stronger and efficient than other type of flanges.

This type of flange is suitable in elevated temperature areas, where the stress and pressure are higher. It is available in many shapes and sizes. It can be FF (Flat Face), RF (Raised Face), or RTJ (Ring Joint) type. These flanges and their fabrication process are expensive, as it needs high-skilled labor to butt-weld them.


The blind flange is a blank circular plate with bolt holes. Technically we connect blind flanges with another type of flanges to strengthen the piping system or terminate the pipeline at the end.

This type of flange is available in different shapes and sizes. It can be only FF (Flat Face) type.


Mangalam Metal Corporation supplies high-quality and best precision-engineered flanges from manufacturers from all around the world. We fully tested all our products to meet national and international standards. Speak to our sales team today to know more about the product and pricing details.

Add a Comment

Your email address will not be published.

Get Free Quote

    This will close in 0 seconds

    Open chat