Valve Flange Faces: RF vs FF vs RTJ and How to Choose
Quick Answer
The three common valve flange facings are raised face (RF), flat face (FF), and ring-type joint (RTJ). RF is standard for most steel valves with a soft gasket. FF protects brittle bodies and matches flat-face piping. RTJ uses a metal ring for severe high-pressure and high-temperature service.
The Three Facings
| Facing | Gasket | Typical use |
|---|---|---|
| Raised face (RF) | Soft (spiral wound, flat) | General steel piping |
| Flat face (FF) | Full-face soft | Cast iron, brittle bodies |
| Ring-type joint (RTJ) | Metal ring (octagonal or oval) | High pressure, high temperature, sour |
Raised Face
The gasket seals on the raised ring, concentrating load. RF is the workhorse for carbon and stainless steel valves. See our materials and flanges reference for grade pairings.
Flat Face
FF spreads the load over the full flange, protecting cast iron and other brittle bodies. A full-face gasket is used. FF valves must mate with FF piping; do not pair FF with RF without a properly sized adapter.
Ring-Type Joint
RTJ uses a precision metal ring in a grooved flange. It handles high pressure and temperature and is common in sour service governed by NACE MR0175. It demands careful groove and ring matching. Our sour service guide covers the material side.
Pressure Class Link
Facing choice interacts with pressure class. A Class 150 RF joint is not the same as a PN16 flange; confirm ratings in our PN vs ASME Class guide. For end styles beyond flanges, see end connection types.
References
Flange facing follows ASME B16.5, ASME B16.47, and EN 1092. Confirm the facing and gasket with the piping specification.
Frequently Asked Questions
What is a raised face flange?
A flange with a raised ring where the gasket seals, concentrating load; it is the standard for most steel valves.
When do you use a flat face flange?
For cast iron or brittle bodies and to match flat-face piping, spreading load over the full face.
What is an RTJ flange used for?
High-pressure, high-temperature, and sour service, using a metal ring in a grooved flange.
Can you mix RF and FF flanges?
Not directly. Pairing them needs a full-face gasket or adapter sized for the mismatch.
Does facing affect pressure rating?
The facing does not set the rating, but the gasket and class together determine the safe pressure-temperature envelope.