What is API 6A Flange
API 6A flanges are designed and manufactured according to the API 6A standard. They are primarily used in high-pressure applications in the oil and gas industry, such as wellhead equipment and valves. The API 6A standard specifies the technical requirements for flanges used in wellhead systems, Christmas trees, valves, and other critical equipment, including pressure ratings, dimensions, tolerances, materials, testing requirements, and performance standards.
These flanges are typically designed to withstand high pressure and harsh conditions and are widely applied in wellhead systems and high-pressure pipeline connections. The pressure ratings of API 6A flanges range from 2000 psi to 20000 psi, with common materials including alloy steel and stainless steel, ensuring durability and safety in high-pressure and corrosive environments.
API 6A Flanges Types and Uses
API 6A covers three types of end and outlet flanges:
Type 6B: These flanges can be used as integral, blind, or welding neck flanges. They can also be utilized as threaded flanges.
Type 6BX: These flanges are integral, blind, or welding neck flanges. Some 6BX blind flanges can also function as test flanges.
Segmented Flanges: These are used on dual-completion wells and are integral to the equipment.
Pressure Ratings and Size Ranges of API 6A Flange Types
Rated working pressures and size ranges of flanges
| Rated working pressure MPa (psi) | Flange size range mm (in) | ||
| Type 6B | Type 6BX | Dual segmented | |
| 13,8(2000) | 52 to 540 (2 1/16 to 21 1/4 ) | 679 to 762 (26 3/4 to 30) | / |
| 20,7 (3000) | 52 to 527 (2 1/16 to 20 3/4 ) | 679 to 762 (26 3/4 to 30) | / |
| 34,5(5000) | 52 to 279 (2 1/16 to 11) | 346 to 540 (13 5/8 to 21 1/4 ) | 35 to 103 × 108 (1 3/8 to 4 1/16 × 4 1/4 ) |
| 69,0(10000) | / | 46 to 540 (1 13/16 to 21 1/4 ) | / |
| 103,5(15000) | / | 46 to 476 (1 13/16 to 18 3/4 ) | / |
| 138,0(20000) | / | 46 to 346 (1 13/16 to 13 5/8 ) | / |
Dimensions of API 6A Flanges
Type 6B flanges
Type 6B flanges are of the ring joint type and are not designed for face-to-face make-up. The connection make-up bolting force reacts on the metallic ring gasket. The type 6B flange shall be of the through-bolted or studded design.
- Type 6B flanges for 13,8 MPa rated working pressure
- Type 6B flanges for 20,7 MPa rated working pressure
- Type 6B flanges for 34,5 MPa rated working pressure
Type 6BX flanges
Type 6BX flanges are of the ring-joint type and are designed with a raised face. Depending on tolerances, the connection make-up bolting force can react on the raised face of the flange when the gasket has been properly seated. This support prevents damage to the flange or gasket from excessive bolt torque. Therefore, one of the flanges in a 6BX connection shall have a raised face. The type 6BX flange shall be of the through-bolted or studded design.
- Type 6BX integral flanges for 13,8 MPa; 20,7 MPa; 34,5 MPa and 69,0 MPa rated working pressures
- Type 6BX integral flanges for 103,5 MPa and 138,0 MPa rated working pressures
- Type 6BX welding neck flanges for 69,0 MPa and 103,5 MPa rated working pressures
- Type 6BX welding neck flanges for 138,0 MPa rated working pressure
- Type 6BX blind and test flanges for 69,0 MPa and 103,5 MPa rated working pressures
- Type 6BX blind and test flanges for 103,5 MPa and 138,0 MPa rated working pressures
- Type 6BX blind flanges for 13,8 MPa; 20,7 MPa; 34,5 MPa; 69,0 MPa; 103,5 MPa and 138,0 MPa rated working pressures
Segmented flanges
Segmented flanges are of the ring-joint type and are designed with a recessed face. Depending on tolerances and when the gasket has been properly seated, the connection make-up bolting force can react on the surface outside the recessed face of the flange. This support prevents damage to the flange or gasket from excessive bolt torque. The segmented flange shall be of the through-bolted or studded design.
- Dimensions for 34,5 MPa rated working pressure, segmented flanges for dual completion
Ring gaskets
Types R or RX gaskets shall be used on 6B flanges. Only BX gaskets shall be used with 6BX flanges.
More information:
Type 6B Flanges Dimensions
Type 6BX Flanges Dimensions
