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.

DN 300 PN 10 flange: dimensions, bolt circle and drilling (EN 1092-1)

The DN 300 PN 10 flange to EN 1092-1 is 445 mm (17.52 in) across, with 12 holes of 22 mm (0.87 in) on a 400 mm (15.75 in) bolt circle, for M20 bolts; the pipe is 323.9 mm (12.75 in) 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 103.5 mm (4.08 in).

The DN 300 PN 10 flange as the calculator draws it: the outline, the bore at the pipe outside diameter and the 12 holes.

Dimensions

Outside diameter	445 mm (17.52 in)
Bolt circle (PCD)	400 mm (15.75 in)
Number of holes	12
Hole diameter	22 mm (0.87 in)
Bolts	M20
Pipe outside diameter	323.9 mm (12.75 in)
Angle between holes	30°
First hole from the centre line	15°
Chord between neighbouring holes	103.5 mm (4.08 in)

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°	193.2	51.8
2	45°	141.4	141.4
3	75°	51.8	193.2
4	105°	-51.8	193.2
5	135°	-141.4	141.4
6	165°	-193.2	51.8
7	195°	-193.2	-51.8
8	225°	-141.4	-141.4
9	255°	-51.8	-193.2
10	285°	51.8	-193.2
11	315°	141.4	-141.4
12	345°	193.2	-51.8

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.