Flange Face Types Explained: RF vs FF vs RTJ vs MFM

Flange face type determines the sealing method and is critical for leak-free operation. Choosing the wrong face type can result in gasket failure and dangerous leaks.

Raised Face (RF)

Most common flange face type. The gasket sits on a raised surface (1/16″ for Class 150-300, 1/4″ for Class 400+).

• Pressure Range: Class 150 to 2500
• Gasket Types: Non-metallic, spiral wound, ring joint
• Applications: Oil & gas, chemical, water, general service
• Standards: ASME B16.5, DIN 2501

Flat Face (FF)

Full-face gasket contact. Entire flange surface is flat, used when one flange is cast iron or brittle material.

• Pressure Range: Class 125, 250 (cast iron)
• Gasket Types: Full-face gaskets
• Applications: Water treatment, HVAC, low-pressure

Ring Type Joint (RTJ)

Metal-to-metal sealing. Groove accepts metal ring gasket for high-pressure, high-temperature service.

• Pressure Range: Class 600 to 2500
• Gasket Types: Oval or octagonal metal rings
• Applications: Offshore, high-pressure steam, refinery
• Ring Designs: R, RX, BX series

Male-Female Face (MFM)

Self-aligning design. One flange has raised face, mating flange has matching recess.

• Pressure Range: Class 150 to 2500
• Gasket Types: Ring gaskets
• Applications: Pump connections, frequent disassembly

Tongue-and-Groove (T&G)

Precision alignment. Tongue on one flange fits into groove on mating flange.

• Pressure Range: Class 150 to 2500
• Applications: Valve bonnets, specialty equipment

Face Type Selection Chart

Service Condition	Recommended Face
General Purpose	Raised Face (RF)
High Pressure	RTJ
Cast Iron Piping	Flat Face (FF)
Frequent Maintenance	MFM or T&G