8 inch Class 300 flange dimensions
ASME B16.5 Class 300 flange dimensions for 8 inch (DN 200) pipe. The same bolting dimensions apply to weld neck, slip-on, blind, socket weld, threaded and lap joint flanges of this size and class.
| Nominal size | 8" (DN 200) |
| Pipe OD (bore end) | 219.1 mm |
| Flange outside diameter | 380 mm (14.96 in) |
| Minimum thickness (incl. 1.6 mm RF) | 39.7 mm (1.56 in) |
| Bolt circle diameter (PCD) | 330.2 mm (13.00 in) |
| Number of bolt holes | 12 |
| Bolt hole diameter | 1.00 in (25.4 mm) |
| Stud bolt diameter | 7/8" UNC |
| Raised face height | 1.6 mm (1/16 in) |
A complete 8" Class 300 joint needs 12 stud bolts of 7/8" diameter with 24 heavy hex nuts and one gasket.
Class 300 vs Class 150 — 8"
| Dimension | Class 300 | Class 150 |
|---|---|---|
| OD | 380 mm | 345 mm |
| Thickness | 39.7 mm | 27.0 mm |
| Bolt circle | 330.2 mm | 298.5 mm |
| Bolts | 12 × 7/8" | 8 × 3/4" |
Class 300 and Class 150 flanges do not bolt together — see 8" Class 150.
Frequently asked questions
What is the OD of a 8 inch Class 300 flange?
380 mm (14.96 in) per ASME B16.5.
How many bolts does a 8 inch Class 300 flange have?
12 bolts of 7/8 inch diameter in 1.00 inch holes on a 330.2 mm bolt circle.
What is the thickness of a 8 inch Class 300 flange?
The minimum flange thickness is 39.7 mm, including the 1.6 mm raised face.
Last updated 2026-11-02