01
Weld Neck Flange
ANSI B16.5 Class 150 Forged Flanges
02
Threaded Flange
03
Slip On Flange
04
Lap Joint Flange
05
Socket Weld Flange
06
Blind Flange
| Nom. Pipe Size | O | T | TJ | R | X | #/Dia of Holesa | Bolt Circle Dia | B | B2b | B3 | H | L | L2 | L3c | r | D | Thr |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ½ | 3.50 | 0.38 | 0.44 | 1.38 | 1.19 | 4-0.62 | 2.38 | 0.88 | 0.62 | 0.90 | 0.84 | 0.56 | 1.81 | 0.62 | 0.12 | 0.38 | 0.62 |
| ¾ | 3.88 | 0.44 | 0.50 | 1.69 | 1.50 | 4-0.62 | 2.75 | 1.09 | 0.82 | 1.11 | 1.05 | 0.56 | 2.00 | 0.62 | 0.12 | 0.44 | 0.62 |
| 1 | 4.25 | 0.50 | 0.56 | 2.00 | 1.94 | 4-0.62 | 3.12 | 1.36 | 1.05 | 1.38 | 1.32 | 0.62 | 2.12 | 0.69 | 0.12 | 0.50 | 0.69 |
| 1¼ | 4.62 | 0.56 | 0.62 | 2.50 | 2.31 | 4-0.62 | 3.50 | 1.70 | 1.38 | 1.72 | 1.66 | 0.75 | 2.19 | 0.81 | 0.19 | 0.56 | 0.81 |
| 1½ | 5.00 | 0.62 | 0.69 | 2.88 | 2.56 | 4-0.62 | 3.88 | 1.95 | 1.61 | 1.97 | 1.90 | 0.81 | 2.38 | 0.88 | 0.25 | 0.62 | 0.88 |
| 2 | 6.00 | 0.69 | 0.75 | 3.62 | 3.06 | 4-0.75 | 4.75 | 2.44 | 2.07 | 2.46 | 2.38 | 0.94 | 2.44 | 1.00 | 0.31 | 0.69 | 1.00 |
| 2½ | 7.00 | 0.81 | 0.88 | 4.12 | 3.56 | 4-0.75 | 5.50 | 2.94 | 2.47 | 2.97 | 2.88 | 1.06 | 2.69 | 1.12 | 0.31 | 0.75 | 1.12 |
| 3 | 7.50 | 0.88 | 0.94 | 5.00 | 4.25 | 4-0.75 | 6.00 | 3.57 | 3.07 | 3.60 | 3.50 | 1.12 | 2.69 | 1.19 | 0.38 | 0.81 | 1.19 |
| 3½ | 8.50 | 0.88 | 0.94 | 5.50 | 4.81 | 8-0.75 | 7.00 | 4.07 | 3.55 | 4.10 | 4.00 | 1.19 | 2.75 | 1.25 | 0.38 | 0.88 | 1.25 |
| 4 | 9.00 | 0.88 | 0.94 | 6.19 | 5.31 | 8-0.75 | 7.50 | 4.57 | 4.03 | 4.60 | 4.50 | 1.25 | 2.94 | 1.31 | 0.44 | 0.94 | 1.31 |
| 5 | 10.00 | 0.88 | 0.94 | 7.31 | 6.44 | 8-0.88 | 8.50 | 5.66 | 5.05 | 5.69 | 5.56 | 1.38 | 3.44 | 1.44 | 0.44 | 0.94 | 1.44 |
| 6 | 11.00 | 0.94 | 1.00 | 8.50 | 7.56 | 8-0.88 | 9.50 | 6.72 | 6.07 | 6.75 | 6.63 | 1.50 | 3.44 | 1.56 | 0.50 | 1.06 | 1.56 |
| 8 | 13.50 | 1.06 | 1.12 | 10.62 | 9.69 | 8-0.88 | 11.75 | 8.72 | 7.98 | 8.75 | 8.63 | 1.69 | 3.94 | 1.75 | 0.50 | 1.25 | 1.75 |
| 10 | 16.00 | 1.12 | 1.19 | 12.75 | 12.00 | 12-1.00 | 14.25 | 10.88 | 10.02 | 10.92 | 10.75 | 1.88 | 3.94 | 1.94 | 0.50 | 1.31 | 1.94 |
| 12 | 19.00 | 1.19 | 1.25 | 15.00 | 14.38 | 12-1.00 | 17.00 | 12.88 | 12.00 | 12.92 | 12.75 | 2.12 | 4.44 | 2.19 | 0.50 | 1.56 | 2.19 |
| 14 | 21.00 | 1.31 | 1.38 | 16.25 | 15.75 | 12-1.12 | 18.75 | 14.14 | 13.25 | 14.18 | 14.00 | 2.19 | 4.94 | 3.12 | 0.50 | 1.63 | 2.25 |
| 16 | 23.50 | 1.38 | 1.44 | 18.50 | 18.00 | 16-1.12 | 21.25 | 16.16 | 15.25 | 16.19 | 16.00 | 2.44 | 4.94 | 3.44 | 0.50 | 1.75 | 2.50 |
| 18 | 25.00 | 1.50 | 1.56 | 21.00 | 19.88 | 16-1.25 | 22.75 | 18.18 | 17.25 | 18.20 | 18.00 | 2.62 | 5.44 | 3.81 | 0.50 | 1.94 | 2.69 |
| 20 | 27.50 | 1.62 | 1.69 | 23.00 | 22.00 | 20-1.25 | 25.00 | 20.20 | 19.25 | 20.25 | 20.00 | 2.81 | 5.62 | 4.06 | 0.50 | 2.13 | 2.88 |
| 22 | 29.50 | 1.75 | 1.81 | 25.25 | 24.25 | 20-1.38 | 27.25 | 22.22 | 21.25 | 22.25 | 22.00 | 3.07 | 5.82 | 4.25 | 0.50 | 2.38 | 3.13 |
| 24 | 32.00 | 1.81 | 1.88 | 27.25 | 26.12 | 20-1.38 | 29.50 | 24.25 | 23.25 | 24.25 | 24.00 | 3.19 | 5.94 | 4.38 | 0.50 | 2.50 | 3.25 |
Dimensions are in inches.
(a)- Bolt hole diameter 1/8 in. larger than bolt diameter. (b)- Standard bore dimensions provided. See bore chart for other wall thicknesses. (c)- This dimension is commonly associated with “true” lap joints. Industry standard is to make to the slip on length through the hub.
Frequently Asked Questions
- What pressure can a Class 150 flange handle?
- An ASME B16.5 Class 150 flange in A105 carbon steel is rated to 285 psi at 100°F. Despite the "150" in the name, the working pressure is 285 psi at ambient temperature and drops as temperature rises (to about 170 psi at 500°F). Always confirm the pressure-temperature rating for your specific material grade.
- What sizes do Class 150 flanges come in?
- ASME B16.5 covers Class 150 flanges from NPS 1/2" through 24". For larger diameters, the equivalent standard is ASME B16.47 Series A and B.
- What is the difference between Class 150 and Class 300?
- Class 300 carries a higher pressure rating than Class 150 (740 psi vs 285 psi at 100°F in A105) and uses a thicker flange with a different, non-interchangeable bolt pattern. Choose the class from the pressure-temperature rating your service requires.
- What flange types are available in Class 150?
- Class 150 is available in every ASME B16.5 type we stock: weld neck, slip-on, blind, threaded, socket weld, and lap joint, in raised face (RF) or flat face (FF).
- How many bolts does a Class 150 flange use?
- It depends on the size. ASME B16.5 bolt-hole counts are always a multiple of four, from 4 bolts on small sizes up to 20 on a 24" flange. See our flange bolt chart for the exact bolt count, size, and bolt circle for each diameter.
