Flange and bolt chart

A flange bolt chart provides the bolt size, number of bolts, and flange dimensions for different flange pressure ratings. Below is a general chart for ANSI B16.5 flanges (widely used in industrial applications).

Flange Bolt Chart (ANSI B16.5 - Class 150 & 300)

Nominal Pipe Size (NPS) Class 150 - Bolt Details Class 300 - Bolt Details

1/2" (4) 1/2" x 2" (4) 1/2" x 2-1/4"

3/4" (4) 1/2" x 2-1/4" (4) 5/8" x 2-3/4"

1" (4) 1/2" x 2-1/2" (4) 5/8" x 3"

1-1/2" (4) 1/2" x 2-3/4" (4) 3/4" x 3-1/4"

2" (4) 5/8" x 3" (8) 3/4" x 3-1/2"

3" (4) 5/8" x 3-1/4" (8) 3/4" x 3-3/4"

4" (8) 5/8" x 3-1/2" (8) 3/4" x 4-1/4"

6" (8) 3/4" x 3-3/4" (12) 7/8" x 4-3/4"

8" (8) 3/4" x 4" (12) 7/8" x 5"

10" (12) 7/8" x 4-1/4" (16) 1" x 5-1/2"

12" (12) 7/8" x 4-1/2" (16) 1-1/8" x 6"

14" (12) 1" x 4-3/4" (20) 1-1/4" x 6-1/2"

16" (16) 1" x 5" (20) 1-1/4" x 7"

Key Points:

The bolt size, number of bolts, and length vary based on the flange class and pipe size.

Class 300 flanges require larger and more bolts than Class 150 flanges due to higher pressure resistance.

Proper gasket selection is essential for a leak-proof connection.

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