6 inch Class 150 flange dimensions
ASME B16.5 Class 150 flange dimensions for 6 inch (DN 150) 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 | 6" (DN 150) |
| Pipe OD (bore end) | 168.3 mm |
| Flange outside diameter | 280 mm (11.02 in) |
| Minimum thickness (incl. 1.6 mm RF) | 23.9 mm (0.94 in) |
| Bolt circle diameter (PCD) | 241.3 mm (9.50 in) |
| Number of bolt holes | 8 |
| Bolt hole diameter | 0.88 in (22.4 mm) |
| Stud bolt diameter | 3/4" UNC |
| Raised face height | 1.6 mm (1/16 in) |
A complete 6" Class 150 joint needs 8 stud bolts of 3/4" diameter with 16 heavy hex nuts and one gasket.
Class 150 vs Class 300 — 6"
| Dimension | Class 150 | Class 300 |
|---|---|---|
| OD | 280 mm | 320 mm |
| Thickness | 23.9 mm | 35.0 mm |
| Bolt circle | 241.3 mm | 269.9 mm |
| Bolts | 8 × 3/4" | 12 × 3/4" |
Class 150 and Class 300 flanges do not bolt together — see 6" Class 300.
Frequently asked questions
What is the OD of a 6 inch Class 150 flange?
280 mm (11.02 in) per ASME B16.5.
How many bolts does a 6 inch Class 150 flange have?
8 bolts of 3/4 inch diameter in 0.88 inch holes on a 241.3 mm bolt circle.
What is the thickness of a 6 inch Class 150 flange?
The minimum flange thickness is 23.9 mm, including the 1.6 mm raised face.
Last updated 2026-11-02