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.

3 inch class 300 flange: dimensions, bolt circle and drilling (ASME B16.5)

The 3 inch class 300 flange to ASME B16.5 is 8.25 in (209.6 mm) across, with 8 holes of 0.88 in (22.2 mm) on a 6.62 in (168.3 mm) bolt circle, for 3/4 in bolts; the pipe is 3.5 in (88.9 mm) outside. The holes straddle the centre lines, the first one 22.5° off, and the chord between neighbouring holes, which is the divider setting for stepping the drilling out, is 2.54 in (64.4 mm).

The 3 inch class 300 flange as the calculator draws it: the outline, the bore at the pipe outside diameter and the 8 holes.

Dimensions

Outside diameter	8.25 in (209.6 mm)
Bolt circle (PCD)	6.62 in (168.3 mm)
Number of holes	8
Hole diameter	0.88 in (22.2 mm)
Bolts	3/4 in
Pipe outside diameter	3.5 in (88.9 mm)
Angle between holes	45°
First hole from the centre line	22.5°
Chord between neighbouring holes	2.54 in (64.4 mm)

Draw this flange: 1:1 template and DXF

Hole coordinates

From the centre of the flange, in mm, with the first hole 22.5° off the horizontal axis and the others counter-clockwise, as the standards lay the drilling out.

Hole	Angle	x (mm)	y (mm)
1	22.5°	77.7	32.2
2	67.5°	32.2	77.7
3	112.5°	-32.2	77.7
4	157.5°	-77.7	32.2
5	202.5°	-77.7	-32.2
6	247.5°	-32.2	-77.7
7	292.5°	32.2	-77.7
8	337.5°	77.7	-32.2

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.