ASME/ANSI B16.5 Flanges and Bolt Dimensions - Class 150 to 2500
Flange dimensions are determined by the pipe size and the pressure class required for the application. Flanges are standardized according publications from organizations like ASME, MSS, API and others.
ASME/ANSI B16.5 provides
- weld neck
- slip-on
- socket weld
- threaded
- lap joint
- blind
flange dimensions for pipes ranging 1/2" to 24" - in classes ranging 150 to 2500. Note that the ratings are in steps with terminology like ASME class xxx or API xxxx.
In general you need to specify the schedule (thickness) of the connected pipe when it is being butt welded to the flange. Socket welded and threaded connections is unaffected by wall thickness and should only require the OD.
| Nominal Pipe Size NPS (inches) | Class 150 | ||||
|---|---|---|---|---|---|
| Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Diameter of Bolt Holes (inches) | Bolt Circle (inches) | |
| 1/4 | 3-3/8 | 4 | 1/2 | 0.62 | 2-1/4 |
| 1/2 | 3-1/2 | 4 | 1/2 | 0.62 | 2-3/8 |
| 3/4 | 3-7/8 | 4 | 1/2 | 0.62 | 2-3/4 |
| 1 | 4-1/4 | 4 | 1/2 | 0.62 | 3-1/8 |
| 1-1/4 | 4-5/8 | 4 | 1/2 | 0.62 | 3-1/2 |
| 1-1/2 | 5 | 4 | 1/2 | 0.62 | 3-7/8 |
| 2 | 6 | 4 | 5/8 | 0.75 | 4-3/4 |
| 2-1/2 | 7 | 4 | 5/8 | 0.75 | 5-1/2 |
| 3 | 7-1/2 | 4 | 5/8 | 0.75 | 6 |
| 3-1/2 | 8-1/2 | 8 | 5/8 | 0.75 | 7 |
| 4 | 9 | 8 | 5/8 | 0.75 | 7-1/2 |
| 5 | 10 | 8 | 3/4 | 0.88 | 8-1/2 |
| 6 | 11 | 8 | 3/4 | 0.88 | 9-1/2 |
| 8 | 13-1/2 | 8 | 3/4 | 0.88 | 11-3/4 |
| 10 | 16 | 12 | 7/8 | 1 | 14-1/4 |
| 12 | 19 | 12 | 7/8 | 1 | 17 |
| 14 | 21 | 12 | 1 | 1.12 | 18-3/4 |
| 16 | 23-1/2 | 16 | 1 | 1.12 | 21-1/4 |
| 18 | 25 | 16 | 1-1/8 | 1.25 | 22-3/4 |
| 20 | 27-1/2 | 20 | 1-1/8 | 1.25 | 25 |
| 24 | 32 | 20 | 1-1/4 | 1.38 | 29-1/2 |
- 1 inch = 25.4 mm
| Nominal Pipe Size NPS (inches) | Class 300 | ||||
|---|---|---|---|---|---|
| Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Diameter of Bolt Holes (inches) | Bolt Circle (inches) | |
| 1/4 | 3-3/8 | 4 | 1/2 | 0.62 | 2-1/4 |
| 1/2 | 3-3/4 | 4 | 1/2 | 0.62 | 2-5/8 |
| 3/4 | 4-5/8 | 4 | 5/8 | 0.75 | 3-1/4 |
| 1 | 4-7/8 | 4 | 5/8 | 0.75 | 3-1/2 |
| 1-1/4 | 5-1/4 | 4 | 5/8 | 0.75 | 3-7/8 |
| 1-1/2 | 6-1/8 | 4 | 3/4 | 0.88 | 4-1/2 |
| 2 | 6-1/2 | 8 | 5/8 | 0.75 | 5 |
| 2-1/2 | 7-1/2 | 8 | 3/4 | 0.88 | 5-7/8 |
| 3 | 8-1/4 | 8 | 3/4 | 0.88 | 6-5/8 |
| 3-1/2 | 9 | 8 | 3/4 | 0.88 | 7-1/4 |
| 4 | 10 | 8 | 3/4 | 0.88 | 7-7/8 |
| 5 | 11 | 8 | 3/4 | 0.88 | 9-1/4 |
| 6 | 12-1/2 | 12 | 3/4 | 0.88 | 10-5/8 |
| 8 | 15 | 12 | 7/8 | 1 | 13 |
| 10 | 17-1/2 | 16 | 1 | 1.12 | 15-1/4 |
| 12 | 20-1/2 | 16 | 1-1/8 | 1.25 | 17-3/4 |
| 14 | 23 | 20 | 1-1/8 | 1.25 | 20-1/4 |
| 16 | 25-1/2 | 20 | 1-1/4 | 1.38 | 22-1/2 |
| 18 | 28 | 24 | 1-1/4 | 1.38 | 24-3/4 |
| 20 | 30-1/2 | 24 | 1-1/4 | 1.38 | 27 |
| 24 | 36 | 24 | 1-1/2 | 1.62 | 32 |
|
Nominal Pipe Size | Class 400 | ||||
|---|---|---|---|---|---|
| Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Diameter of Bolt Holes (inches) | Bolt Circle (inches) | |
| 1/4 | 3-3/8 | 4 | 1/2 | 0.62 | 2-1/4 |
| 1/2 | 3-3/4 | 4 | 1/2 | 0.62 | 2-5/8 |
| 3/4 | 4-5/8 | 4 | 5/8 | 0.75 | 3-1/4 |
| 1 | 4-7/8 | 4 | 5/8 | 0.75 | 3-1/2 |
| 1-1/4 | 5-1/4 | 4 | 5/8 | 0.75 | 3-7/8 |
| 1-1/2 | 6-1/8 | 4 | 3/4 | 0.88 | 4-1/2 |
| 2 | 6-1/2 | 8 | 5/8 | 0.75 | 5 |
| 2-1/2 | 7-1/2 | 8 | 3/4 | 0.88 | 5-7/8 |
| 3 | 8-1/4 | 8 | 3/4 | 0.88 | 6-5/8 |
| 3-1/2 | 9 | 8 | 7/8 | 1 | 7-1/4 |
| 4 | 10 | 8 | 7/8 | 1 | 7-7/8 |
| 5 | 11 | 8 | 7/8 | 1 | 9-1/4 |
| 6 | 12-1/2 | 12 | 7/8 | 1 | 10-5/8 |
| 8 | 15 | 12 | 1 | 1.12 | 13 |
| 10 | 17-1/2 | 16 | 1-1/8 | 1.25 | 15-1/4 |
| 12 | 20-1/2 | 16 | 1-1/4 | 1.38 | 17-3/4 |
| 14 | 23 | 20 | 1-1/4 | 1.38 | 20-1/4 |
| 16 | 25-1/2 | 20 | 1-3/8 | 1.5 | 22-1/2 |
| 18 | 28 | 24 | 1-3/8 | 1.5 | 24-3/4 |
| 20 | 30-1/2 | 24 | 1-1/2 | 1.62 | 27 |
| 24 | 36 | 24 | 1-3/4 | 1.88 | 32 |
| Nominal Pipe Size NPS (inches) | Class 600 | ||||
|---|---|---|---|---|---|
| Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Diameter of Bolt Holes (inches) | Bolt Circle (inches) | |
| 1/4 | 3-3/8 | 4 | 1/2 | 0.62 | 2-1/4 |
| 1/2 | 3-3/4 | 4 | 1/2 | 0.62 | 2-5/8 |
| 3/4 | 4-5/8 | 4 | 5/8 | 0.75 | 3-1/4 |
| 1 | 4-7/8 | 4 | 5/8 | 0.75 | 3-1/2 |
| 1-1/4 | 5-1/4 | 4 | 5/8 | 0.75 | 3-7/8 |
| 1-1/2 | 6-1/8 | 4 | 3/4 | 0.88 | 4-1/2 |
| 2 | 6-1/2 | 8 | 5/8 | 0.75 | 5 |
| 2-1/2 | 7-1/2 | 8 | 3/4 | 0.88 | 5-7/8 |
| 3 | 8-1/4 | 8 | 3/4 | 0.88 | 6-5/8 |
| 3-1/2 | 9 | 8 | 7/8 | 1 | 7-1/4 |
| 4 | 10-3/4 | 8 | 7/8 | 1 | 8-1/2 |
| 5 | 13 | 8 | 1 | 1.12 | 10-1/2 |
| 6 | 14 | 12 | 1 | 1.12 | 11-1/2 |
| 8 | 16-1/2 | 12 | 1-1/8 | 1.25 | 13-3/4 |
| 10 | 20 | 16 | 1-1/4 | 1.38 | 17 |
| 12 | 22 | 20 | 1-1/4 | 1.38 | 19-1/4 |
| 14 | 23-3/4 | 20 | 1-3/8 | 1.5 | 20-3/4 |
| 16 | 27 | 20 | 1-1/2 | 1.62 | 23-3/4 |
| 18 | 29-1/4 | 20 | 1-5/8 | 1.75 | 25-3/4 |
| 20 | 32 | 24 | 1-5/8 | 1.75 | 28-1/2 |
| 24 | 37 | 24 | 1-7/8 | 2 | 33 |
| Nominal Pipe Size NPS (inches) | Class 900 | ||||
|---|---|---|---|---|---|
| Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Diameter of Bolt Holes (inches) | Bolt Circle (inches) | |
| 1/2 | 4-3/4 | 4 | 3/4 | 0.88 | 3-1/4 |
| 3/4 | 5-1/8 | 4 | 3/4 | 0.88 | 3-1/2 |
| 1 | 5-7/8 | 4 | 7/8 | 1 | 4 |
| 1-1/4 | 6-1/4 | 4 | 7/8 | 1 | 4-3/8 |
| 1-1/2 | 7 | 4 | 1 | 1.12 | 4-7/8 |
| 2 | 8-1/2 | 8 | 7/8 | 1 | 6-1/2 |
| 2-1/2 | 9-5/8 | 8 | 1 | 1.12 | 7-1/2 |
| 3 | 9-1/2 | 8 | 7/8 | 1 | 7-1/2 |
| 4 | 11-1/2 | 8 | 1-1/8 | 1.25 | 9-1/4 |
| 5 | 13-3/4 | 8 | 1-1/4 | 1.38 | 11 |
| 6 | 15 | 12 | 1-1/8 | 1.25 | 12-1/2 |
| 8 | 18-1/2 | 12 | 1-3/8 | 1.5 | 15-1/2 |
| 10 | 21-1/2 | 16 | 1-3/8 | 1.5 | 18-1/2 |
| 12 | 24 | 20 | 1-3/8 | 1.5 | 21 |
| 14 | 25-1/4 | 20 | 1-1/2 | 1.62 | 22 |
| 16 | 27-3/4 | 20 | 1-5/8 | 1.75 | 24-1/2 |
| 18 | 31 | 20 | 1-7/8 | 2 | 27 |
| 20 | 33-3/4 | 20 | 2 | 2.12 | 29-1/2 |
| 24 | 41 | 20 | 2-1/2 | 2.62 | 35-1/2 |
| Nominal Pipe Size NPS (inches) | Class 1500 | ||||
|---|---|---|---|---|---|
| Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Diameter of Bolt Holes (inches) | Bolt Circle (inches) | |
| 1/2 | 4-3/4 | 4 | 3/4 | 0.88 | 3-1/4 |
| 3/4 | 5-1/8 | 4 | 3/4 | 0.88 | 3-1/2 |
| 1 | 5-7/8 | 4 | 7/8 | 1 | 4 |
| 1-1/4 | 6-1/4 | 4 | 7/8 | 1 | 4-3/8 |
| 1-1/2 | 7 | 4 | 1 | 1.12 | 4-7/8 |
| 2 | 8-1/2 | 8 | 7/8 | 1 | 6-1/2 |
| 2-1/2 | 9-5/8 | 8 | 1 | 1.12 | 7-1/2 |
| 3 | 10-1/2 | 8 | 1-1/8 | 1.25 | 8 |
| 4 | 12-1/4 | 8 | 1-1/4 | 1.38 | 9-1/2 |
| 5 | 14-3/4 | 8 | 1-1/2 | 1.62 | 11-1/2 |
| 6 | 15-1/2 | 12 | 1-3/8 | 1.5 | 12-1/2 |
| 8 | 19 | 12 | 1-5/8 | 1.75 | 15-1/2 |
| 10 | 23 | 12 | 1-7/8 | 2 | 19 |
| 12 | 26-1/2 | 16 | 2 | 2.12 | 22-1/2 |
| 14 | 29-1/2 | 16 | 2-1/4 | 2.38 | 25 |
| 16 | 32-1/2 | 16 | 2-1/2 | 2.62 | 27-3/4 |
| 18 | 36 | 16 | 2-3/4 | 2.88 | 30-1/2 |
| 20 | 38-3/4 | 16 | 3 | 3.12 | 32-3/4 |
| 24 | 46 | 16 | 3-1/2 | 3.62 | 39 |
| Nominal Pipe Size NPS (inches) | Class 2500 | ||||
|---|---|---|---|---|---|
| Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Diameter of Bolt Holes (inches) | Bolt Circle (inches) | |
| 1/2 | 5-1/4 | 4 | 3/4 | 0.88 | 3-1/2 |
| 3/4 | 5-1/2 | 4 | 3/4 | 0.88 | 3-3/4 |
| 1 | 6-1/4 | 4 | 7/8 | 1 | 4-1/4 |
| 1-1/4 | 7-1/4 | 4 | 1 | 1.12 | 5-1/8 |
| 1-1/2 | 8 | 4 | 1-1/8 | 1.25 | 5-3/4 |
| 2 | 9-1/4 | 8 | 1 | 1.12 | 6-3/4 |
| 2-1/2 | 10-1/2 | 8 | 1-1/8 | 1.25 | 7-3/4 |
| 3 | 12 | 8 | 1-1/4 | 1.38 | 9 |
| 4 | 14 | 8 | 1-1/2 | 1.62 | 10-3/4 |
| 5 | 16-1/2 | 8 | 1-3/4 | 1.88 | 12-3/4 |
| 6 | 19 | 8 | 2 | 2.12 | 14-1/2 |
| 8 | 21-3/4 | 12 | 2 | 2.12 | 17-1/4 |
| 10 | 26-1/2 | 12 | 2-1/2 | 2.62 | 21-1/4 |
| 12 | 30 | 12 | 2-3/4 | 2.88 | 24-3/8 |
Insert flanges to your Sketchup model with the Engineering ToolBox Sketchup Extension
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