450A JIS 10K flange: dimensions, bolt circle and drilling (JIS B 2220)

The 450A JIS 10K flange to JIS B 2220 is 620 mm (24.41 in) across, with 20 holes of 27 mm (1.06 in) on a 565 mm (22.24 in) bolt circle, for M24 bolts; the pipe is 457.2 mm (18 in) outside. The holes straddle the centre lines, the first one 9° off, and the chord between neighbouring holes, which is the divider setting for stepping the drilling out, is 88.4 mm (3.48 in).

Download the 1:1 drilling template (free PDF) Open in the generator: DXF for plasma and laser

On A4 or Letter sheets to tape together, with a check ruler on every sheet: print at actual size, 100 %. No account needed.

Dimensions

Outside diameter	620 mm (24.41 in)
Flange thickness (t)	30 mm (1.18 in)
Bolt circle (PCD)	565 mm (22.24 in)
Number of holes	20
Hole diameter	27 mm (1.06 in)
Bolts	M24
Pipe outside diameter	457.2 mm (18 in)
Angle between holes	18°
First hole from the centre line	9°
Chord between neighbouring holes	88.4 mm (3.48 in)

The thickness of the steel flange in JIS B 2220; cast iron flanges are thicker. The bolts are metric, M24, and their length depends on the gasket and the type of flange.

Hole coordinates

From the centre of the flange, in mm, with the first hole 9° off the horizontal axis and the others counter-clockwise, as the standards lay the drilling out.

Bolt tightening order

1 – 11 – 6 – 16 → 3 – 13 – 8 – 18 → 5 – 15 – 10 – 20 → 2 – 12 – 7 – 17 → 4 – 14 – 9 – 19

The cross pattern of ASME PCC-1, with the holes numbered as in the table above, so that the gasket is pulled down evenly. Go round in at least three passes, raising the torque each time (about 30 %, 60 % and 100 %), then go round in order until no nut turns. The torque itself depends on the bolt, the gasket and the lubricant: it comes from the gasket or bolt supplier.

Questions

How many bolts does a 450A JIS 10K flange have?

20, of M24, through holes of 27 mm (1.06 in) on a 565 mm (22.24 in) bolt circle.

What is the bolt circle of a 450A JIS 10K flange?

565 mm (22.24 in). The holes are 18° apart, and the first one sits 9° off the centre line, so that two flanges mate in any symmetric position. The chord between neighbouring holes is 88.4 mm (3.48 in).

Can a 450A JIS 10K 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. For pressure service, the flange takes the material, thickness and facing that JIS B 2220 sets for its class.

In what order are the bolts of a 450A JIS 10K flange tightened?

In a cross pattern, with the holes numbered round the flange: 1, 11, 6, 16, 3, 13, 8, 18, 5, 15, 10, 20, 2, 12, 7, 17, 4, 14, 9, 19. In at least three passes, raising the torque each time, and then round in order until no nut turns.