flange It is an important device in the industrial pipe system. One of the factors affecting the strength, attachment and safety of the joints is “Flange Facing” which is designed to suit different applications and pressures.

This article describes the faces of each type of flange that are commonly used, along with advantages, limitations and appropriate selection guidelines.

1. Raised Face (RF)

This type of flange is called “Lifting surface flange” because the gasket surface is lifted above the bolt hole. This type of flange can be used with a variety of gaskets, including a flat ring sheet and a metal-component type such as a ring gasket, a double jacketed gasket.

The purpose of the raised surface type flange is to combine the pressure on the smaller gasket receiving area. This allows the joints to receive more pressure. Diameter and height according to ASME B16.5 standards depending on pressure level and diameter. The pressure level of the flange determines the height of the raised surface.

The surface of the flange, generally according to the ASME B16.5 standard is 125 – 250 μin Ra (3 to 6 μm RA).

Height of the face lifted
The following description applies to the surface of almost any flange. Except for the Lap Joint Flange:
In the pressure layer level 150 and 300, the height of the raised surface is approximately 1.66 mm.
In the pressure layer level 400, 600, 900, 1500 and 2000, the height of the raised surface is approximately 6.4 mm.

2. Flat face (FF)

The surface of the plan, the area where the gasket is received will be smooth as a single surface along the front of the plate. Commonly referred to as “smooth faces” or “flat faces”, cast iron flanges Class 125 or flanges made of other brittle materials. The surface of the flange is Flat Face, which should use a full-size gasket on the plate. To prevent torque and cracking while tightening the nut. and must not be used with a raised type surface

Tongue and Groove (TG)

Tongue and groove surfaces must be compatible. On one of the flanges there is a raised ring (raised ring or tongue), while the flange is paired with a groove (Groove) on the surface.

Tongue and groove flanges are available in both large and small. Unlike the male and female surfaces, the inner diameter of the tongue type and the groove is not extended to the flange base. Therefore, the gasket is fixed both inside and outside the diameter. This flange with a tongue and groove surface type is often used with a pump cover and a valve bonnet.

The joints that use the tongue and groove type flange have the advantage of being able to organize themselves and make it close. This shielded joint maintains a good support angle. And there is no need for a large connection at all.

The surface of the general flange such as RTJ, T&G and F&M should not be used together. Because the surface for the connection of the flange is incompatible. And there is no type of gasket that can help weld.

4. Male and female flange (Male-and-Female – M&F)

The male surface has an area that is stretched more than a normal flange. As for the female surface, there will be deep grooves for pairing together.

The female surface has a depth of 3/16 inches, and the male is 1/4 of the height, both with a smooth surface. The outer diameter of the female surface serves to support and attach the gasket.

Advantages and disadvantages of T&G and M&F flange types