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Types of Pipe Flanges Used in Piping Systems

There are different types of pipe flanges used in the piping systems depending upon the fluid, PT rating, material of construction, connecting equipment etc.

Flange face

Below are the types of flanges used in piping based on facing.
Raised Face (RF) flanges:

These pipe flanges are the most commonly used flanges. The raised face thickness for 150# and 300# are included in the specified flange thickness and for higher rating they are not included in the flange thickness.

Raised Face height
Flange raised face (RF)
Flat Face (FF) flanges:

These pipe flanges are used when the counter flanges are flat face. They are mainly used at connection to cast iron equipment, valves and specialties. This flat face flange has a gasket surface in the same plane as the bolting circle face.


Flange flat face FF
Ring-Type Joint (RTJ) flange

These pipe flanges are most reliable type of flange joint but are costlier than the other type of flanges.


Flange ring joint (RG)

The Ring Type Joint flanges are generally used in high pressure (Class 600 and higher rating) and/or high temperature services above 800°F (427°C).

Tongue-and-Groove (T&G) face flange:

These pipe flanges are most reliable type of flange joint but are costlier than the other type of flanges.


Flange tongue groove joint (TG)
Male-and-Female (M&F) flanges:

These pipe flanges are better version of Raised face flanges.


Flange male female (MF)
What is the difference between a RTJ, FF, and RF flange on seals and thermowells?

The raised face, RF, is the standard process connection on our third party seals and thermowells. Both have options for a RTJ and FF type flange connections. The Raised Face (RF) is the most common type used in process plant applications.

The gasket surface of the flange is raised above the bolting circle face. A Ring-type Joint (RTJ) can also have a raised gasket face with the difference being the ring groove machined in this face.

This groove will accommodate a steel ring gasket for flange mating. The Flat Face, FF, flange has a gasket surface that is in the same plane as the bolting circle face.

None of these three flange types are interchangeable between types, i.e. RTJ flange cannot be mated to a RF flange. ​

Standard we supply
ANSI
AWWA
ASME
DIN


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