Raised Face Flanges

A Raised Face (RF) flange is the most common type of pipe flange used in process industries, featuring a small, elevated surface (or “raised face”) around the pipe bore above the bolt circle. This design concentrates bolt pressure onto a smaller gasket area, creating a stronger, tighter seal compared to flat-faced flanges.

Standard Specification for Raised Face Flanges

Dimensions : ANSI B16.5, ANSI B16.47 Series A & B, MSS SP44, ASA, API-605, AWWA, Custom Drawings
Size : 1/2″ (15 NB) to 48″ (1200NB)
Class: 150 LBS, 300 LBS, 600 LBS, 900 LBS, 1500 LBS, 2500 LBS, DIN Standard ND-6,10, 16, 25, 40 Etc.
Flange Face Type: Flat Face (FF), Raised Face (RF)

Material & Grades of Raised Face Flanges :

Carbon Steel Raised Face Flanges :
ASTM / ASME A/SA 105 ASTM / ASME A 350, ASTM A 181 LF 2 / A516 Gr.70 A36, A694 F42, F46, F52, F60, F65, F706

Stainless Steel Raised Face Flanges :
ASTM A 182, A 240 F 304, 304L, 304H, 316, 316L, 316Ti, 310, 310S, 321, 321H, 317, 347, 347H, 904L

Low Temperature Carbon Steel Raised Face Flanges:  ASTM A350, LF2, LF3

Alloy Steel Raised Face Flanges :
ASTM / ASME A/SA 182 & A 387 F1, F5, F9, F11, F12, F22, F91

Key Characteristics and Uses Design:

The sealing face is raised above the bolting circle plane by roughly 1/16 inch for lower pressure classes and 1/4 inch for higher classes.
Purpose: The raised surface creates higher pressure on the gasket, increasing the sealing strength and pressure containment capability.
Applications: Widely used in oil & gas, petrochemical, water and sewage, and power generation industries for piping systems, valves, and equipment.
Gaskets: Suitable for use with flat ring sheet gaskets, spiral wound gaskets, and double-jacketed gaskets.
Standards: Defined by ASME B16.5 and ASME B16.47 standards

Raised Face vs. Other

• FacesFlat Face (FF): Typically used for lower-pressure applications (like cast iron) where the entire face is flat, requiring a full-face gasket.
• Ring Type Joint (RTJ): Specifically for high-pressure, severe, or high-temperature applications where a metal ring is used as a seal, sometimes utilizing a specially machined groove within a raised face.

Raised Face Flanges vs Flat Face Pipe Flanges

Raised Face Flange Pressure Ratings