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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Low-Pressure Iron and Steel Threaded Pipe Fittings
Use these fittings for low-pressure applications in noncorrosive environments.

- For Use With: Air, Steam, Oil, Water, Natural Gas
- Presure Class:
Steel: 150
Iron: 125 - Pipe Nipples and Pipe: Use Schedule 40 steel
Pipe Size | Plug Construction | Max. Pressure | Max. Steam Pressure | Material | Each | |
NPT Male | ||||||
---|---|---|---|---|---|---|
1/8 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 00000 |
1/4 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 000 |
3/8 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 000 |
1/2 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 000 |
3/4 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 000 |
1 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 0000 |
1 1/4 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 0000 |
1 1/2 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 00000 |
2 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Steel | 000000000 | 00000 |
2 1/2 | Hollow | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
3 | Hollow | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
3 1/2 | Hollow | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
4 | Hollow | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
Low-Pressure Iron and Steel Threaded Pipe Fittings with Sealant
To prevent leaks in low-pressure lines, the male threads on these fittings have an acrylic sealant already applied for extra protection. Also known as Pressure Class 125 or 150 fittings. Made of either iron or steel, they’re best in noncorrosive environments. Even with sealant, threaded connections can be taken apart for maintenance and repair.

- For Use With: Air, Diesel Fuel, Gasoline, Natural Gas, Oil, Water
- Pressure Class: 150
- Specifications Met: See table
- Pipe Nipples and Pipe: Use Schedule 40 Iron and Steel
Pipe Size | Plug Construction | Max. Pressure | Material | Specifications Met | Each | |
NPT Male | ||||||
---|---|---|---|---|---|---|
1/2 | Solid | 150 psi @ 72° F | Steel | SAE J531 | 0000000 | 00000 |
3/4 | Solid | 150 psi @ 72° F | Steel | SAE J531 | 0000000 | 0000 |
1 | Solid | 150 psi @ 72° F | Steel | SAE J531 | 0000000 | 0000 |
1 1/4 | Solid | 150 psi @ 72° F | Steel | ASME B16.14 | 0000000 | 0000 |
2 | Solid | 150 psi @ 72° F | Steel | ASME B16.14 | 0000000 | 00000 |
FM-Approved Low-Pressure Cast Iron Threaded Pipe Fittings
Suitable for use in fire-protection applications, these pipe fittings are made of cast iron, so they are brittle and can be quickly opened with the strike of a sledge hammer. They are also known as Pressure Class 125 fittings. Use in noncorrosive environments.

- For Use With: Air, Steam, Oil, Water, Natural Gas
- Pressure Class: 125
- Specifications Met: FM Approved, UL Listed, ASTM A126, ASME B1.20.1, ASME B16.4
- Pipe Nipples and Pipe: Use Schedule 40 steel
Pipe Size | Plug Construction | Max. Pressure | Max. Steam Pressure | Material | Each | |
NPT Male | ||||||
---|---|---|---|---|---|---|
1 | Solid | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
1 1/4 | Solid | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
1 1/2 | Solid | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
2 | Solid | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
2 1/2 | Solid | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
3 | Solid | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 00000 |
4 | Solid | 175 psi @ 72° F | 125 psi @ 350° F | Iron | 000000000 | 000000 |
Low-Pressure Galvanized Iron and Steel Threaded Pipe Fittings
The galvanized finish on these fittings provides fair corrosion resistance. Fittings are for use in low-pressure applications.

- For Use With: Air, Steam, Oil, Water, Natural Gas
- Pressure Class: 150
- Specifications Met: SAE J531
- Pipe Nipples and Pipe: Use Schedule 40 steel
- Flanges: Use Class 150 galvanized steel
Pipe Size | Plug Construction | Max. Pressure | Max. Steam Pressure | Material | Each | |
NPT Male | ||||||
---|---|---|---|---|---|---|
1/8 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 00000 |
1/4 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 000 |
3/8 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 000 |
1/2 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 000 |
3/4 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 000 |
1 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 0000 |
1 1/4 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 0000 |
1 1/2 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 00000 |
2 | Solid | 150 psi @ 72° F | 150 psi @ 350° F | Galvanized Steel | 00000000 | 00000 |
Low-Pressure Galvanized Iron and Steel Threaded Pipe Fittings with Sealant
The male threads on these fittings have a sealant applied for extra leak protection. Fittings are made of galvanized iron or steel, which have fair corrosion resistance. Also known as Pressure Class 125 or 150 fittings, they are for use in low-pressure applications.
NPTF (Dryseal) threads are compatible with NPT threads.

- For Use With: Air, Oil, Natural Gas, Water
- Pressure Class: 150
- Specifications Met: SAE J531
- Pipe Nipples and Pipe: Use Schedule 40 galvanized steel
- Flanges: Use Class 150 galvanized steel
Pipe Size | Plug Construction | Max. Pressure | Max. Steam Pressure | Each | |
NPTF Male | |||||
---|---|---|---|---|---|
1/8 | Solid | 150 psi @ 72° F | Not Rated | 0000000 | 00000 |
1/4 | Solid | 150 psi @ 72° F | Not Rated | 0000000 | 000 |
3/8 | Solid | 150 psi @ 72° F | Not Rated | 0000000 | 000 |
1/2 | Solid | 150 psi @ 72° F | Not Rated | 0000000 | 000 |
3/4 | Solid | 150 psi @ 72° F | Not Rated | 0000000 | 000 |
1 | Solid | 150 psi @ 72° F | Not Rated | 0000000 | 0000 |