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.
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Medium-Pressure Steel Threaded Pipe Flanges
- For Use With: Air, Natural Gas, Oil, Steam, Water
- Pressure Class: See table
- Specifications Met: ASTM A105, ASME B16.5
- Pipe Nipples and Pipe: Use Schedule 80 steel
- Fittings: Use Class 300 or Schedule 80 iron and steel
With better strength than our low-pressure steel flanges, these are for use in medium-pressure applications. Bolt two same-size flanges together with a gasket (sold separately) to create an access point within a line. Flanges are also known as Pressure Class 300 or Pressure Class 600 flanges. Use 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 | Material | Each | |
NPT | ||||||||||
Pressure Class 300 | ||||||||||
| 1/2 | 3 3/4" | 1/2" | 5/8" | 4 | 2 5/8" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 000000 |
| 3/4 | 4 5/8" | 5/8" | 3/4" | 4 | 3 1/4" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 00000 |
| 1 | 4 7/8" | 5/8" | 3/4" | 4 | 3 1/2" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 00000 |
| 1 1/4 | 5 1/4" | 5/8" | 3/4" | 4 | 3 7/8" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 00000 |
| 1 1/2 | 6 1/8" | 3/4" | 7/8" | 4 | 4 1/2" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 00000 |
| 2 | 6 1/2" | 5/8" | 3/4" | 8 | 5" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 00000 |
| 2 1/2 | 7 1/2" | 3/4" | 7/8" | 8 | 5 7/8" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 00000 |
| 3 | 8 1/4" | 3/4" | 7/8" | 8 | 6 5/8" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 00000 |
| 4 | 10" | 3/4" | 7/8" | 8 | 7 7/8" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 00000 |
| 5 | 11" | 3/4" | 7/8" | 8 | 9 1/4" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 000000 |
| 6 | 12 1/2" | 3/4" | 7/8" | 12 | 10 5/8" | 600 psi @ 72° F | 300 psi @ 300° F | Steel | 00000000 | 000000 |
Pressure Class 600 | ||||||||||
| 1 | 4 7/8" | 3/4" | 3/4" | 4 | 3 1/2" | 1,400 psi @ 72° F | 1,300 psi @ 300° F | Steel | 00000000 | 00000 |
| 1 1/2 | 6 1/8" | 7/8" | 0.88" | 4 | 4 1/2" | 1,400 psi @ 72° F | 1,300 psi @ 300° F | Steel | 00000000 | 00000 |
| 2 | 6 1/2" | 3/4" | 3/4" | 8 | 5" | 1,400 psi @ 72° F | 1,300 psi @ 300° F | Steel | 00000000 | 00000 |
| 3 | 8 1/4" | 7/8" | 0.88" | 8 | 6.62" | 1,400 psi @ 72° F | 1,300 psi @ 300° F | Steel | 00000000 | 000000 |
| 4 | 10 3/4" | 1" | 1" | 8 | 8 1/2" | 1,400 psi @ 72° F | 1,300 psi @ 300° F | Steel | 00000000 | 000000 |
| 6 | 14" | 1 1/8" | 1.12" | 12 | 11 1/2" | 1,400 psi @ 72° F | 1,300 psi @ 300° F | Steel | 00000000 | 000000 |
Medium-Pressure Galvanized Steel Threaded Pipe Flanges
- For Use With: Air, Natural Gas, Steam, Water
- Pressure Class : 300
- Specifications Met: ASTM A123, ASTM A105, ASME B16.5
- Pipe Nipples and Pipe: Use Schedule 80 steel
- Fittings: Use Class 300 iron or steel
A galvanized finish gives these flanges fair corrosion resistance. Also known as Pressure Class 300 flanges, they can withstand medium-pressure applications. Bolt two same-size flanges 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.
Bolt Hole | ||||||||
|---|---|---|---|---|---|---|---|---|
| Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Each | |
NPT | ||||||||
| 3/4 | 4 5/8" | 3/4" | 3/4" | 4 | 3 1/4" | 600 psi @ 72° F | 0000000 | 0000000 |
| 1 | 4 7/8" | 3/4" | 3/4" | 4 | 3 1/2" | 600 psi @ 72° F | 0000000 | 00000 |
| 1 1/4 | 5 1/4" | 3/4" | 3/4" | 4 | 3 7/8" | 600 psi @ 72° F | 0000000 | 000000 |
| 1 1/2 | 6 1/8" | 7/8" | 0.88" | 4 | 4 1/2" | 600 psi @ 72° F | 0000000 | 00000 |
| 2 | 6 1/2" | 3/4" | 3/4" | 8 | 5" | 600 psi @ 72° F | 0000000 | 000000 |
| 3 | 8 1/4" | 7/8" | 0.88" | 8 | 6 5/8" | 600 psi @ 72° F | 0000000 | 000000 |
| 4 | 10" | 7/8" | 0.88" | 8 | 7 7/8" | 600 psi @ 72° F | 0000000 | 000000 |