How to Identify and Measure Fittings
Pipe size is an industry designation, not the actual size. View information about how to measure threaded and unthreaded pipe and pipe fittings.
More
FM-Approved Low-Pressure Cast Iron Threaded Pipe Flanges
Suitable for use in fire-protection applications, these flanges are brittle and can be quickly opened with the strike of a sledge hammer. Bolt two flanges of the same size together with a gasket (sold separately) to create an access point within a line. Use in noncorrosive environments.
Reducing flanges transition your system to a smaller pipe size. Attach them to a flange with a larger pipe size but with the same flange dimensions.
For technical drawings and 3-D models, click on a part number.


- For Use With: Air, Natural Gas, Oil, Steam, Water
- Specifications Met:
3/4 Pipe Size: ASME B1.20.1, ASME B16.1, ASTM A126, FM Approved
All other sizes: ASME B1.20.1, ASME B16.1, ASTM A126, FM Approved, UL Listed - Pipe Nipples and Pipe: Use Schedule 40 steel
- Fittings: Use Class 125 iron and steel
Bolt Hole | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Max. Steam Pressure | Material | Each | |
NPT | ||||||||||
3/4 | 3 7/8" | 1/2" | 5/8" | 4 | 2 3/4" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
1 | 4 1/4" | 1/2" | 5/8" | 4 | 3 1/8" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
1 1/4 | 4 5/8" | 1/2" | 5/8" | 4 | 3 1/2" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
1 1/2 | 5" | 1/2" | 5/8" | 4 | 3 7/8" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
2 | 6" | 5/8" | 3/4" | 4 | 4 3/4" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
5 | 10" | 3/4" | 7/8" | 8 | 8 1/2" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
8 | 13 1/2" | 3/4" | 7/8" | 8 | 11 3/4" | 125 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |



- For Use With: Air, Natural Gas, Oil, Steam, Water
- Specifications Met: ASME B1.20.1, ASME B16.1, ASTM A126, ASTM A153, FM Approved
- Pipe Nipples and Pipe: Use Schedule 40 iron and steel
- Fittings: Use Class 125 iron and steel
Bolt Hole | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Pipe Size | For Flange Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Max. Steam Pressure | Material | Each | |
NPT | |||||||||||
2 | 2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
2 | 3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
2 | 4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
3 | 4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
4 | 6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
Low-Pressure Steel Threaded Pipe Flanges
Use these flanges for low-pressure applications in noncorrosive environments. Bolt two flanges of the same size together with a gasket (sold separately) to create an access point within a line.
For technical drawings and 3-D models, click on a part number.


- For Use With: Air, Natural Gas, Oil, Steam, Water
- Pressure Class: 150
- Specifications Met:
NPT: ASME B16.5, ASTM A105, MSS SP-25
BSPT: ASTM A105 - Fittings: Use Class 125 or 150 iron and steel
- Pipe Nipples and Pipe: Use Schedule 40 steel
Bolt Hole | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Max. Steam Pressure | Material | Each | |
BSPT | ||||||||||
1/2 | 3 1/2" | 1/2" | 5/8" | 4 | 2 3/8" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 000000 |
3/4 | 3 7/8" | 1/2" | 5/8" | 4 | 2 3/4" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 00000 |
1 | 4 1/4" | 1/2" | 5/8" | 4 | 3 1/8" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 00000 |
1 1/4 | 4 5/8" | 1/2" | 5/8" | 4 | 3 1/2" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 00000 |
1 1/2 | 5" | 1/2" | 5/8" | 4 | 3 7/8" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 00000 |
2 | 6" | 5/8" | 3/4" | 4 | 4 3/4" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 000000 |
2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 000000 |
3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 000000 |
4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 000000 |
6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 285 psi @ 72° F | 230 psi @ 300° F | Steel | 0000000 | 000000 |
FM-Approved Low-Pressure Cast Iron Unthreaded Pipe Flanges


- For Use With: Air, Diesel Fuel, Gasoline, Natural Gas, Oil, Steam, Water
- Pressure Class: 125
- Specifications Met: ASME B1.20.1, ASME B16.1, ASTM A126, FM Approved
- Pipe Nipples and Pipe: Use Schedule 40 steel
- Fittings: Use Class 125 or 150 iron and steel
FM-approved for fire protection applications, these flanges are cast iron, so they're brittle and can be quickly opened by hitting them with a sledge hammer. Bolt them together with a gasket (not included) to create an access point within a low-pressure pipe line. All are cap flanges, which are also known as blind flanges. Use them in noncorrosive environments.
For technical drawings and 3-D models, click on a part number.
Bolt Hole | |||||||||
---|---|---|---|---|---|---|---|---|---|
Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Max. Steam Pressure | Each | |
1 | 4 1/4" | 1/2" | 5/8" | 4 | 3 1/8" | 200 psi @ 72° F | 165 psi @ 300° F | 0000000 | 000000 |
1 1/2 | 5" | 1/2" | 5/8" | 4 | 3 7/8" | 200 psi @ 72° F | 165 psi @ 300° F | 0000000 | 00000 |
2 | 6" | 5/8" | 3/4" | 4 | 4 3/4" | 200 psi @ 72° F | 165 psi @ 300° F | 0000000 | 00000 |
2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 200 psi @ 72° F | 165 psi @ 300° F | 0000000 | 00000 |
3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 200 psi @ 72° F | 165 psi @ 300° F | 0000000 | 00000 |
3 1/2 | 8 1/2" | 5/8" | 3/4" | 8 | 7" | 200 psi @ 72° F | 165 psi @ 300° F | 0000000 | 000000 |
4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 200 psi @ 72° F | 165 psi @ 300° F | 0000000 | 000000 |
6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 200 psi @ 72° F | 165 psi @ 300° F | 0000000 | 000000 |