What Is A Flange Coupling And What Types Of Flange Couplings Are There?

The purpose of a flange coupling is quite simple. It is a driving coupling between rotating shafts that consists of flanges, one of which is fixed at the end of each shaft. The two flanges bolted together with a ring set of bolts completes the drive connection.

Flange coupling

Flange coupling involves bringing the two tube ends together in a flush, sealed manner. The two-piece coupling unit consists of a keyed receiving side for the flanged end to be fastened. The reason being it may be married to the opposing tube end, which also has a flanged end.

Most flange coupling assemblies have either a female or male coupler opening so that when the two ends are brought together, they are aligned without causing drag or resistance in the material being passed through them. The female or male coupling method also creates a stable connection, resistant to shifting, keeping the flange coupling sturdily in place.

A flange coupling is useful in pressurizing the piping systems where tubing ends or two pipes need to come together. The connecting methods for flange couplings are usually quite strong. The reason is either the pressure of the material or the sometimes hazardous nature of the materials passed through many industrial piping systems. Bolt connections and high thread count nut are used to securing the flange coupling place. These bolts and nuts are usually made from tempered alloys or steel to provide the enduring strength and ability to tighten to the utmost level and ensure that the piping system doesn’t leak at any flanged junction.

Flange Couplings


Keys are machine elements used to prevent any relative rotational movement between a mounted shaft and the parts mounted on it.

If you want to make the joint, grooves or keyways are cut on the surface of the shaft and in the hub of the part to be mounted.

Mounting at an intermediate location on the shaft, the key is placed firmly in the keyway of the shaft, and then the part to be mounted is slid, until it gets fully engaged.

Types of Flange Coupling

The need for couplings arises after purchasing a heavy working costly motor and pump for it because they both need to be well-connected and ensure to be utilized properly while protecting the other components at the same time.

It is unavoidable to couple both the shafts, and it would be simple if they could be seamlessly aligned, and shafts never moved because of the machine vibrations.

Usually, there are 3 types of flange couplings; they can be classified as protected, unprotected, and marine flange coupling.

Protected Flange Coupling

If you want to make it protected, this kind of flange coupling, the protruding nuts and screws are shielded by flanges on both parts of the coupling. This kind of course of action helps to sidestep risks for the laborers.

Marine Flange Coupling

When it comes to Marine Flange Coupling, flanges are formed integrally with the shafts. Depending on the perimeter of the shafts, the number of bolts used is decided. It ranges from 4 to 12 bolts. These types of flange coupling elongated bolts without a head are used to hold the shafts together.

Unprotected Flange Coupling

When we talk about unprotected flange coupling, each shaft is entered in the main flange with a security key that modifies into the keyways of both shafts and the essential flange of the machine. The flanges are consolidated with the assistance of bolts and screws.

If we talk about these types of coupling, about three to six screws are utilized to affix the flanges. Keyways may cause a debilitating impact on the flange coupling by making a gap. If you want to moderate the equivalent, the keys are balanced at the correct point along the perimeter of the shafts.


The growing industrialization and an upsurge in need of technological advancement and engineering tools are taking place worldwide, and specific large companies have built up new industrial applications around them. We at Texas Flange are the leaders in manufacturing a wide range of products, and though couplings are not our specialty, we love to help our customers find what they need.

If you have any further inquiries, contact Texas Flange today!

How to Remove Exhaust Flange Bolts Easily?

Although not in our supply chain, we have had a few questions regarding other types of flange bolting and installation. Here is a basic guide to exhaust flange assembly.

Exhaust flanges consist of a pair of metal sections that join your exhaust pipe together. They are helpful in conjunction with an exhaust set of bolts and gaskets. The usual options of exhaust flanges are the 3 bolt or 2 bolt types. Usually, m10 with the 2 bolt option is helpful, and an m8 bolt for the 3 bolt. The recommended grade of bolts is 8.8 tensile or higher so that you can tighten them without stretching or breaking the bolts. There is also the use of locking nuts, Loctite, or spring washers. It helps to prevent the nuts from vibrating loose.

How Exhaust Flanges Work

Exhaust flanges work with the use of a set of bolts and gaskets to join them together. When you set up a wastegate pipe or exhaust for ease of fitment, you must use v bands or exhaust flanges to enable the sections to re-fit or pull off for access. You can also use exhaust flanges without gaskets, and for that, you need to use automotive-grade silicon.

How to Remove Exhaust Flange Bolts Easily

Welding Exhaust Flanges

Welding exhaust flanges are almost the same thing as welding v band flanges. The essential factor to start with is tack welds every 20-30mm. It helps prevent distortion stitch weld the flange and let it cool down between welding.

How to Remove the Exhaust Flange Bolts

The changing temperatures from cold to hot of the exhaust system together without changing the moisture conditions can result in speeding up the rusting of the flange bolts. If the rust progresses, it could reach the threads, and these may go useless. It is essential to replace and release the flange bolts. You need to apply heat to remove the rust from the threads. If the threads are unusable, you need to cut the bolts from the flange.

Here are a few easy steps to remove the exhaust flange bolts easily:

Keep a check if the area on the flange bolts has no fuel lines as well as combustibles. Clearance of all the combustibles underneath the vicinity for safety is essential.

Use gloves and goggles to protect your hands and eyes.

It is better to have a fire extinguisher closer in case the fire starts.

Ignite the torch carefully. Make sure that the bright blue flame is half or one inch long.

The tip of the torch must be 6-8 inches away from the flange bolt until it has a dull orange color. You need to turn off your torch. Heat the bolt slowly and do not use air to trigger it.

It is better to let the flange bolt cool down and place the socket that fits the bolt to the ratchet.

Slide the socket to the nut that is at the flange bolt. If the bolt loosens, continue with the same process for the rest of the bolts. If it doesn’t budge, go to the next step.

Keep the tip 3-4 inches further and set the flames again.

Heat the bolt once again and when it turns to a bright orange glow, use the air to trigger and blow out more oxygen. Bolt would then start to meltdown.

Turn your torch off and quickly hammer the threaded side of the flange bolt. Repeat the process until the bolt is out of the exhaust.

Let the hot bolt cool down for around thirty minutes. Make sure no combustible materials are lying around before you leave the area.

Throw the cut bolts after another hour or two to ensure that the bolts are at room temperature and won’t cause fires in the garbage bin.


If the problem persists and it becomes impossible to remove the exhaust flange bolts, it is better to consult professionals. Contact your local supplier for more information.