8 inch class 300 flange: dimensions, bolt circle and drilling (ASME B16.5)
The 8 inch class 300 flange to ASME B16.5 is 15 in (381 mm) across, with 12 holes of 1 in (25.4 mm) on a 13 in (330.2 mm) bolt circle, for 7/8 in bolts; the pipe is 8.63 in (219.1 mm) outside. The holes straddle the centre lines, the first one 15° off, and the chord between neighbouring holes, which is the divider setting for stepping the drilling out, is 3.36 in (85.5 mm).
Dimensions
| Outside diameter | 15 in (381 mm) |
|---|---|
| Bolt circle (PCD) | 13 in (330.2 mm) |
| Number of holes | 12 |
| Hole diameter | 1 in (25.4 mm) |
| Bolts | 7/8 in |
| Pipe outside diameter | 8.63 in (219.1 mm) |
| Angle between holes | 30° |
| First hole from the centre line | 15° |
| Chord between neighbouring holes | 3.36 in (85.5 mm) |
Draw this flange: 1:1 template and DXF
Hole coordinates
From the centre of the flange, in mm, with the first hole 15° off the horizontal axis and the others counter-clockwise, as the standards lay the drilling out.
| Hole | Angle | x (mm) | y (mm) |
|---|---|---|---|
| 1 | 15° | 159.5 | 42.7 |
| 2 | 45° | 116.7 | 116.7 |
| 3 | 75° | 42.7 | 159.5 |
| 4 | 105° | -42.7 | 159.5 |
| 5 | 135° | -116.7 | 116.7 |
| 6 | 165° | -159.5 | 42.7 |
| 7 | 195° | -159.5 | -42.7 |
| 8 | 225° | -116.7 | -116.7 |
| 9 | 255° | -42.7 | -159.5 |
| 10 | 285° | 42.7 | -159.5 |
| 11 | 315° | 116.7 | -116.7 |
| 12 | 345° | 159.5 | -42.7 |
Questions
- How many bolts does a %{size} %{class} flange have?
- %{holes}, of %{bolt}, through holes of %{hole} on a %{circle} bolt circle.
- What is the bolt circle of a %{size} %{class} flange?
- %{circle}. The holes are %{angle}° apart, and the first one sits %{half}° off the centre line, so that two flanges mate in any symmetric position. The chord between neighbouring holes is %{chord}.
- Can a %{size} %{class} flange be cut from plate?
- As a plate flange, for low pressure: ducts, tanks, water lines. The outline and the drilling above are what the flange calculator draws, with the 1:1 template and the DXF for plasma or laser. A pressure flange to %{standard} is forged, with a hub and a raised face, and its thickness and facing come from the standard.