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.
- What are the bolt hole dimensions for a Class 150 flange?
- Bolt hole dimensions for an ASME B16.5 Class 150 flange are set by nominal pipe size. Each size specifies a bolt circle diameter, a bolt hole diameter, and a bolt count. A 4 inch Class 150 flange, for example, has 8 holes of 0.75 inch diameter on a 7.50 inch bolt circle, with a 9.00 inch outside diameter. Full bolt hole dimensions for every size from 1/2 inch through 24 inch are in the Class 150 dimension table on this page, and bolt and stud sizes are on the Texas Flange bolt chart.
- What does the # symbol mean in 150# flange?
- The # symbol is shorthand for pressure class, so 150# and Class 150 mean the same thing. It is a class designation, not a weight and not a direct pressure rating. A Class 150 carbon steel flange in Material Group 1.1 is rated to 285 psig at -20 to 100 degrees F, and that rating falls as temperature rises.
- What is the difference between Class 150 and Class 600 flanges?
- Class 600 flanges are rated for roughly five times the working pressure of Class 150 at the same temperature. In Material Group 1.1 at -20 to 100 degrees F, Class 150 is rated to 285 psig and Class 600 to 1480 psig. Class 600 flanges are thicker, heavier, and use larger bolting, so the two are not interchangeable even where bolt circles appear similar. See the Class 600 dimension tables.
- Are Class 150 flange dimensions the same as ANSI B16.5 and ASME B16.5?
- Yes. ANSI B16.5 and ASME B16.5 refer to the same standard, so a flange described as ANSI B16.5 Class 150 and one described as ASME B16.5 Class 150 have identical dimensions. ANSI is the accrediting body and ASME publishes the standard. The dimensions on this page apply under either name.
