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Flange Guide

Dimensions in Inches Weld Neck Flanges and Stud Bolts ASME B16.5 Class 2500

Weld Neck flange

Important Information

Other Pressure Classes

NPS DIA
D
THK
B
DIA
A
DIA
OD
HEIGHT
H
DIA
K
DIA
L
1/2 5.25 1.19 1.69 0.84 2.88 3.5 7/8
3/4 5.5 1.25 2 1.05 3.12 3.75 7/8
1 6.25 1.38 2.25 1.32 3.5 4.25 1
7.25 1.5 2.88 1.66 3.75 5.12 1.1/8
8 1.75 3.12 1.9 4.38 5.75
2 9.25 2 3.75 2.38 5 6.75 1.1/8
10.5 2.25 4.5 2.88 5.62 7.75
3 12 2.62 5.25 3.5 6.62 9 1.3/8
4 14 3 6.5 4.5 7.5 10.75 1.5/8
5 16.5 3.62 8 5.56 9 12.75 1.7/8
6 19 4.25 9.25 6.63 10.75 14.5 2.1/8
8 21.75 5 12 8.63 12.5 17.25 2.1/8
10 26.5 6.5 14.75 10.75 16.5 21.25 2.5/8
12 30 7.25 17.38 12.75 18.25 24.38 2.7/8
Weld Neck flange
NPS NO OF
BOLT
HOLES
DIA
STUD
BOLTS
LENGTH
STUD
BOLTS
1/2 4 3/4 4.75
3/4 4 3/4 5
1 4 7/8 5.5
4 1 6
4 1.1/8 6.75
2 8 1 7
8 1.1/8 7.75
3 8 8.75
4 8 10
5 8 11.75
6 8 2 13.5
8 12 2 15
10 12 19.25
12 12 21.25

Notes:

Measuring lengths of Stud Bolts and Hex bolts
Dimensional Tolerances of Weld Neck Flanges ASME B16.5
Outside Diameter *
Tolerances not listed in ASME B16.5 2013
≤24
0.06 in (1.6 mm)
>24
±0.12 in (±3.2 mm)
Diameter Hub at Base
≤24
0.06 in (1.6 mm)
>24
±0.12 in (±3.2 mm)
Inside Diameter
≤10
±0.03 in (±0.8 mm)
12 thru 18
0.06 in (1.6 mm)
≥20
±0.12 in / -0.06 in
(+3.2 mm / -1.6 mm)
Diameter Hub at Point of Welding
≤5
±0.09 in / -0.03 in
(+2.4 mm / -0.8 mm)
≥6
+0.15 in / -0.03 in
(+4.0 mm / -0.8 mm)

Drilling
Bolt Circle
0.06 in (1.6 mm)
Bolt Hole Spacing
±0.03 in (±0.8 mm)
Eccentricity Bolt Circle
≤2½
0.03 in max (0.8 mm max)
≥3
0.06 in max (1.6 mm max)
Thickness
≤18
+0.12 in / -0 (+3.2 mm / -0)
≥20
+0.18 in / -0 (+4.8 mm / -0)
Length thru Hub
≤10
0.06 in (1.6 mm)
≥12
±0.12 in (±3.2 mm)
Diameter Contact Face
0.06 in RF (1.6 mm)
±0.03 in (±0.8 mm)
0.25 in RF (6.35 mm)
±0.01 in (±0.4 mm)

Tongue and Groove
±0.01 in (±0.4 mm)
Male-Female
±0.01 in (±0.4 mm)
Welding bevel
PP
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Raised Face Height

For the height measures H and B of all described dimensions of flanges on this website, with exception of the Lap Joint Flange, it is important to understand and remember the following:

In Pressure Classes 150 and 300, the height of raised face is approximately 1.6 mm (1/16 inch).
In these two Pressure Classes, almost all suppliers of flanges, show in their catalog or brochure, the H and B dimensions including the raised face height. See figure 1 on the image below.

Raised face height

In Pressure Classes 400, 600, 900, 1500 and 2500, the height of raised face is approximately 6.4 mm (1/4 inch). In these Pressure Classes, most suppliers show the H and B dimensions excluding the raised face height. See figure 2 on the image above.

On this site you will find two dimensions. The top row dimensions are excluding the raised face height, and in the bottom row the dimensions are including the raised face height.