Flanges are used to connect pipes with each other, to valves, to fittings, and to specialty items such as strainers and pressure vessels. A cover plate can be connected to create a "blind flange". Flanges are typically threaded or welded, and two flanges are connected by bolting them with gaskets to form a seal that allows easy access to the pipe system.
There are many different flange standards to be found worldwide. To allow easy functionality and interchangeability, these are designed to have standardized dimensions. Common world standards include ASA/ASME (USA), PN/DIN (European), BS10 (British/Australian), and JIS/KS (Japanese/Korean). ASME B16.5 covers flanges up to 24 inches size and up to pressure rating of Class 2500. Flanges larger than 24 inches are covered in ASME B16.47.
Standard | Type | Facing | Size | Rating | Bore or Wall Thickness | |
ANSI B16.5 | SLIP ON | FF, RF | 1/2"-24" | CL150-1500 | STD | |
WELD NECK | RF, RTJ | 1/2"-24" | CL150-2500 | STD, SCH20, SCH30, SCH40 | ||
LAP JOINT | FF, RF | 1/2"-24" | CL150-2500 | STD | ||
BLIND | FF | 1/2"-3" | CL150-1500 | STD | ||
THREADED | RF | 1/2"-24" | CL150-2500 | STD | ||
BS 3293 | WELD NECK | RF, RTJ | 1/2"-48" | CL150-600 | STD, SCH20, SCH30, SCH40 | |
SLIP ON | FF, RF | 26"-48" | CL150-600 | STD | ||
ANSI B16.47 A | WELD NECK | RF, RTJ | 12"-60" | CL150-900 | STD, SCH20, SCH30, SCH40 | |
ANSI B16.47 B | WELD NECK | RF, RTJ | 26"-60" | CL75-900 | STD, SCH20, SCH30, SCH40 | |
MSS SP44 | BLIND | FF | 12"-60" | CL150-900 | STD | |
WELD NECK | RF, RTJ | 12"-60" | CL150-900 | STD, SCH20, SCH30, SCH40 | ||
API 605 | BLIND | FF | 12"-60" | CL75-900 | STD | |
WELD NECK | RF, RTJ | 12"-60" | CL75-900 | STD, SCH20, SCH30, SCH40 | ||
API 6A | 6B | BLIND | RF | 2 1/16"-21 1/4" | 2000-5000psi | STD |
WELD NECK | RF, RTJ | 2 1/16"-21 1/4" | 2000-5000psi | STD, SCH20, SCH30, SCH40 | ||
THREADED | FF, RF | 2 1/16"-21 1/4" | 2000-5000psi |
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6BX | BLIND | RF | 2 1/16"-26 3/4" | 2000-20000psi | STD | |
WELD NECK | RF, RTJ | 2 1/16"-21 1/4" | 2000-20000psi | STD, SCH20, SCH30, SCH40 | ||
THREADED | FF, RF | 2 16"-21 1/4" | 2000-20000psi |
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AWWA C207 | RING | FF, RF | 4"-72" | CLASS B(86PSI) | STD, CUSTOMED | |
BLIND | FF | 4"-72" | CLASS B(86PSI), | STD, CUSTOMED | ||
HUB | FF, RF | 4"-72" | CLASS D (175-150PSI) | STD, CUSTOMED | ||
Type | Pressure Capacity | Pipe Sizes | Usage |
Threaded | Low | Small | Attaching without welding |
Lap Joint | Low | All | Systems that need frequent disassembly |
Slip on | Low | All | Low installation cost; easy assembly |
Blind | Very high | All | Flow pressure testing; closing pipes |
Weld Neck | High | All | High-pressure systems; extreme temperatures |
