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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Aluminum Unthreaded Pipe Flanges
Also known as Pressure Class 125 flanges, these are for use in low-pressure applications. Bolt two same-size flanges together with a gasket (sold separately) to create an access point within a line. Flanges are aluminum, which is lightweight with good corrosion resistance.
Butt-weld flanges are also known as weld-neck flanges; the flange neck has a beveled end that, when flush to pipe, creates a trough for a strong weld. Slip-on weld flanges have no internal stop; slide a pipe through the flange and weld on both sides. Reducing flanges let you transition your system to a smaller pipe size; attach to a flange with a larger pipe size but with the same flange dimensions. Cap flanges are also known as blind flanges.
- For Use With: Air, Oil, Water
- Pressure Class: 125
- Specifications Met: ASME B16.1
- Fittings: Use Schedule 40 aluminum
- Pipe: Use Schedule 40 aluminum
Bolt Hole | ||||||||
|---|---|---|---|---|---|---|---|---|
Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Each | |
| 1/2 | 3 1/2" | 1/2" | 5/8" | 4 | 2 3/8" | 150 psi @ 72° F | 000000000 | 000000 |
| 3/4 | 3 7/8" | 1/2" | 5/8" | 4 | 2 3/4" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 | 4 1/4" | 1/2" | 5/8" | 4 | 3 1/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/2 | 5" | 1/2" | 5/8" | 4 | 3 7/8" | 150 psi @ 72° F | 000000000 | 000000 |
| 2 | 6" | 5/8" | 3/4" | 4 | 4 3/4" | 150 psi @ 72° F | 000000000 | 000000 |
| 2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 150 psi @ 72° F | 000000000 | 000000 |
| 4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
- For Use With: Air, Oil, Water
- Pressure Class: 125
- Specifications Met: ASME B16.1
- Fittings: Use Schedule 40 aluminum
- Pipe: Use Schedule 40 aluminum
Bolt Hole | ||||||||
|---|---|---|---|---|---|---|---|---|
| Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Each | |
| 1/2 | 3 1/2" | 1/2" | 5/8" | 4 | 2 3/8" | 150 psi @ 72° F | 00000000 | 000000 |
| 3/4 | 3 7/8" | 1/2" | 5/8" | 4 | 2 3/4" | 150 psi @ 72° F | 00000000 | 00000 |
| 1 | 4 1/4" | 1/2" | 5/8" | 4 | 3 1/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/4 | 4 5/8" | 1/2" | 5/8" | 4 | 3 1/2" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/2 | 5" | 1/2" | 5/8" | 4 | 3 7/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 2 | 6" | 5/8" | 3/4" | 4 | 4 3/4" | 150 psi @ 72° F | 000000000 | 00000 |
| 2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 150 psi @ 72° F | 000000000 | 00000 |
| 3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 150 psi @ 72° F | 000000000 | 00000 |
| 4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 8 | 13 1/2" | 3/4" | 7/8" | 8 | 11 3/4" | 150 psi @ 72° F | 000000000 | 000000 |
- For Use With: Air, Oil, Water
- Pressure Class: 125
- Specifications Met: ASME B16.1
- Fittings: Use Schedule 40 aluminum
- Pipe: Use Schedule 40 aluminum
- For Use With: Air, Oil, Water
- Pressure Class: 125
- Specifications Met: ASME B16.1
- Fittings: Use Schedule 40 aluminum
- Pipe: Use Schedule 40 aluminum
Bolt Hole | ||||||||
|---|---|---|---|---|---|---|---|---|
| Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Each | |
| 1/2 | 3 1/2" | 1/2" | 5/8" | 4 | 2 3/8" | 150 psi @ 72° F | 000000000 | 000000 |
| 3/4 | 3 7/8" | 1/2" | 5/8" | 4 | 2 3/4" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 | 4 1/4" | 1/2" | 5/8" | 4 | 3 1/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/4 | 4 5/8" | 1/2" | 5/8" | 4 | 3 1/2" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/2 | 5" | 1/2" | 5/8" | 4 | 3 7/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 2 | 6" | 5/8" | 3/4" | 4 | 4 3/4" | 150 psi @ 72° F | 000000000 | 00000 |
| 2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 150 psi @ 72° F | 000000000 | 00000 |
| 3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 150 psi @ 72° F | 000000000 | 000000 |
| 4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 8 | 13 1/2" | 3/4" | 7/8" | 8 | 11 3/4" | 150 psi @ 72° F | 000000000 | 000000 |
Low-Pressure Aluminum Threaded Pipe Flanges
Also known as Pressure Class 125 flanges, these are for use in low-pressure applications. Bolt two same-size flanges together with a gasket (sold separately) to create an access point within a line. Flanges are aluminum, which is lightweight with good corrosion resistance.
Reducing flanges allow you to transition your system to a smaller pipe size; attach to a flange with a larger pipe size but with the same flange dimensions.
- For Use With: Air, Oil, Water
- Pressure Class: 125
- Specifications Met:
Pipe Size 1-6: ASME B16.1 - Fittings: Use Class 150 aluminum
- Pipe Nipples and Pipe: Use Schedule 40 aluminum
Bolt Hole | ||||||||
|---|---|---|---|---|---|---|---|---|
| Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Each | |
NPT | ||||||||
| 1/2 | 3 1/2" | 1/2" | 5/8" | 4 | 2 3/8" | 150 psi @ 72° F | 000000000 | 000000 |
| 3/4 | 3 7/8" | 1/2" | 5/8" | 4 | 2 3/4" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 | 4 1/4" | 1/2" | 5/8" | 4 | 3 1/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/4 | 4 5/8" | 1/2" | 5/8" | 4 | 3 1/2" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/2 | 5" | 1/2" | 5/8" | 4 | 3 7/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 2 | 6" | 5/8" | 3/4" | 4 | 4 3/4" | 150 psi @ 72° F | 000000000 | 00000 |
| 2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 150 psi @ 72° F | 000000000 | 00000 |
| 3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 150 psi @ 72° F | 000000000 | 00000 |
| 4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 8 | 13 1/2" | 3/4" | 7/8" | 8 | 11 3/4" | 150 psi @ 72° F | 000000000 | 000000 |
- For Use With: Air, Oil, Water
- Pressure Class: 125
- Specifications Met: ASME B16.1
- Fittings: Use Class 150 aluminum
- Pipe Nipples and Pipe: Use Schedule 40 aluminum
Bolt Hole | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Pipe Size | For Flange Pipe Size | Flange OD | For Bolt Dia. | Dia. | No. of | Bolt Circle Dia. | Max. Pressure | Each | |
NPT | |||||||||
| 1/2 | 3/4 | 3 7/8" | 1/2" | 5/8" | 4 | 2 3/4" | 150 psi @ 72° F | 000000000 | 000000 |
| 3/4 | 1 | 4 1/4" | 1/2" | 5/8" | 4 | 3 1/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 | 1 1/4 | 4 5/8" | 1/2" | 5/8" | 4 | 3 1/2" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/4 | 1 1/2 | 5" | 1/2" | 5/8" | 4 | 3 7/8" | 150 psi @ 72° F | 000000000 | 00000 |
| 1 1/2 | 2 | 6" | 5/8" | 3/4" | 4 | 4 3/4" | 150 psi @ 72° F | 000000000 | 00000 |
| 2 | 2 1/2 | 7" | 5/8" | 3/4" | 4 | 5 1/2" | 150 psi @ 72° F | 000000000 | 00000 |
| 2 | 3 | 7 1/2" | 5/8" | 3/4" | 4 | 6" | 150 psi @ 72° F | 000000000 | 000000 |
| 3 | 4 | 9" | 5/8" | 3/4" | 8 | 7 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 4 | 6 | 11" | 3/4" | 7/8" | 8 | 9 1/2" | 150 psi @ 72° F | 000000000 | 000000 |
| 6 | 8 | 13 1/2" | 3/4" | 7/8" | 8 | 11 3/4" | 150 psi @ 72° F | 000000000 | 000000 |
Stainless Steel Hex Screw and Nut Kits for Pipe Flanges
Join standard-sized stainless steel and aluminum pipe flanges in corrosive conditions. These kits come with the right size and number of screws and nuts for the bolt holes in each pipe size. For a tight seal, you’ll also need a gasket between the flanges. All screws and nuts meet ASTM and ASME standards or DIN standards for material quality and dimensions. They may be mildly magnetic. Screw length is measured from under the head.
18-8 stainless steel fasteners resist corrosion from mild chemicals and water. They are ideal for wet environments.
316 stainless steel fasteners are more corrosion resistant than 18-8 stainless steel fasteners and have excellent resistance to chemicals and salt water.
Kits with blue PTFE-coated nuts thread together with the screws smoothly thanks to the slippery coating on the nut. The coating also resists chemicals, so it doesn't compromise their corrosion resistance.
Screw | Nut | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| For Pipe Size | Lg. | Min. Thread Lg. | Head Wd. | Head Ht. | Tensile Strength, psi | Wd. | Ht. | No. of Screws Included | No. of Nuts Included | Each | |
18-8 Stainless Steel | |||||||||||
1/2"-13 | |||||||||||
| 1/2, 3/4 | 2" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 00000 |
| 1, 1 1/4 | 2 1/4" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 0000 |
| 1 1/2 | 2 1/2" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 0000 |
5/8"-11 | |||||||||||
| 2 | 2 3/4" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 4 | 4 | 000000000 | 00000 |
| 2 1/2, 3 | 3" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 4 | 4 | 000000000 | 00000 |
| 4 | 3" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 8 | 8 | 000000000 | 00000 |
3/4"-10 | |||||||||||
| 6 | 3 1/4" | 1 3/4" | 1 1/8" | 1/2" | 80,000 | 1 1/8" | 41/64" | 8 | 8 | 000000000 | 00000 |
| 8 | 3 1/2" | 1 3/4" | 1 1/8" | 1/2" | 80,000 | 1 1/8" | 41/64" | 8 | 8 | 000000000 | 00000 |
7/8"-9 | |||||||||||
| 10, 12 | 4" | 2" | 1 5/16" | 37/64" | 80,000 | 1 5/16" | 3/4" | 12 | 12 | 000000000 | 000000 |
316 Stainless Steel | |||||||||||
1/2"-13 | |||||||||||
| 1/2, 3/4 | 2" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 0000 |
| 1, 1 1/4 | 2 1/4" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 00000 |
| 1 1/2 | 2 1/2" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 00000 |
5/8"-11 | |||||||||||
| 2 | 2 3/4" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 4 | 4 | 000000000 | 00000 |
| 2 1/2, 3 | 3" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 4 | 4 | 000000000 | 00000 |
| 4 | 3" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 8 | 8 | 000000000 | 00000 |
3/4"-10 | |||||||||||
| 6 | 3 1/4" | 1 3/4" | 1 1/8" | 1/2" | 80,000 | 1 1/8" | 41/64" | 8 | 8 | 000000000 | 00000 |
| 8 | 3 1/2" | 1 3/4" | 1 1/8" | 1/2" | 80,000 | 1 1/8" | 41/64" | 8 | 8 | 000000000 | 00000 |
7/8"-9 | |||||||||||
| 10, 12 | 4" | 2" | 1 5/16" | 37/64" | 80,000 | 1 5/16" | 3/4" | 12 | 12 | 000000000 | 000000 |
316 Stainless Steel with Blue PTFE-Coated Nuts | |||||||||||
1/2"-13 | |||||||||||
| 1/2, 3/4 | 2" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 00000 |
| 1, 1 1/4 | 2 1/4" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 00000 |
| 1 1/2 | 2 1/2" | 1 1/4" | 3/4" | 11/32" | 80,000 | 3/4" | 7/16" | 4 | 4 | 000000000 | 00000 |
5/8"-11 | |||||||||||
| 2 | 2 3/4" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 4 | 4 | 000000000 | 00000 |
| 2 1/2, 3 | 3" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 4 | 4 | 000000000 | 00000 |
| 4 | 3" | 1 1/2" | 15/16" | 27/64" | 80,000 | 15/16" | 35/64" | 8 | 8 | 000000000 | 00000 |
3/4"-10 | |||||||||||
| 6 | 3 1/4" | 1 3/4" | 1 1/8" | 1/2" | 80,000 | 1 1/8" | 41/64" | 8 | 8 | 000000000 | 00000 |
| 8 | 3 1/2" | 1 3/4" | 1 1/8" | 1/2" | 80,000 | 1 1/8" | 41/64" | 8 | 8 | 000000000 | 00000 |
7/8"-9 | |||||||||||
| 10, 12 | 4" | 2" | 1 5/16" | 37/64" | 80,000 | 1 5/16" | 3/4" | 12 | 12 | 000000000 | 000000 |
Stainless Steel Heavy Hex Screw and Nut Kits for Pipe Flanges
Connect standard-size stainless steel or aluminum pipe flanges with these kits—they come with screws and nuts in the right size and number to match the bolt holes. The screw heads and nuts are 10% wider than standard hex fasteners, so they spread force over a larger area, and you can tighten with more torque. Made from 316 stainless steel, the fasteners in these kits have excellent resistance to chemicals and salt water. They may also be mildly magnetic. For a complete connection, you’ll also need a gasket. Screw length is measured from under the head.
All screws and nuts meet ASTM A193 or A194 standards for high-pressure and high-temperature applications. They also meet ASME B18.2.1 standards for dimensions.
Screw | Nut | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| For Pipe Size | Lg. | Min. Thread Lg. | Head Wd. | Head Ht. | Tensile Strength, psi | Wd. | Ht. | No. of Screws Included | No. of Nuts Included | Each | |
ASTM Grade B8M 316 Stainless Steel for Class 125/150 Pipe Flanges | |||||||||||
1/2"-13 | |||||||||||
| 1/2, 3/4 | 2" | 1 1/4" | 7/8" | 11/32" | 75,000 | 7/8" | 31/64" | 4 | 4 | 000000000 | 000000 |
| 1, 1 1/4 | 2 1/4" | 1 1/4" | 7/8" | 11/32" | 75,000 | 7/8" | 31/64" | 4 | 4 | 000000000 | 00000 |
| 1 1/2 | 2 1/2" | 1 1/4" | 7/8" | 11/32" | 75,000 | 7/8" | 31/64" | 4 | 4 | 000000000 | 00000 |
5/8"-11 | |||||||||||
| 2 | 2 3/4" | 1 1/2" | 1 1/16" | 27/64" | 75,000 | 1 1/16" | 39/64" | 4 | 4 | 000000000 | 00000 |
| 2 1/2, 3 | 3" | 1 1/2" | 1 1/16" | 27/64" | 75,000 | 1 1/16" | 39/64" | 4 | 4 | 000000000 | 00000 |
| 3 1/2, 4 | 3" | 1 1/2" | 1 1/16" | 27/64" | 75,000 | 1 1/16" | 39/64" | 8 | 8 | 000000000 | 00000 |
3/4"-10 | |||||||||||
| 5, 6 | 3 1/4" | 1 3/4" | 1 1/4" | 1/2" | 75,000 | 1 1/4" | 47/64" | 8 | 8 | 000000000 | 000000 |
| 8 | 3 1/2" | 1 3/4" | 1 1/4" | 1/2" | 75,000 | 1 1/4" | 47/64" | 8 | 8 | 000000000 | 00000 |