14 inch Class 300 flange dimensions
ASME B16.5 Class 300 flange dimensions for 14 inch (DN 350) 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 | 14" (DN 350) |
| Pipe OD (bore end) | 355.6 mm |
| Flange outside diameter | 585 mm (23.03 in) |
| Minimum thickness (incl. 1.6 mm RF) | 52.4 mm (2.06 in) |
| Bolt circle diameter (PCD) | 514.4 mm (20.25 in) |
| Number of bolt holes | 20 |
| Bolt hole diameter | 1.25 in (31.8 mm) |
| Stud bolt diameter | 1-1/8" UNC |
| Raised face height | 1.6 mm (1/16 in) |
A complete 14" Class 300 joint needs 20 stud bolts of 1-1/8" diameter with 40 heavy hex nuts and one gasket.
Class 300 vs Class 150 — 14"
| Dimension | Class 300 | Class 150 |
|---|---|---|
| OD | 585 mm | 535 mm |
| Thickness | 52.4 mm | 33.4 mm |
| Bolt circle | 514.4 mm | 476.3 mm |
| Bolts | 20 × 1-1/8" | 12 × 1" |
Class 300 and Class 150 flanges do not bolt together — see 14" Class 150.
Frequently asked questions
What is the OD of a 14 inch Class 300 flange?
585 mm (23.03 in) per ASME B16.5.
How many bolts does a 14 inch Class 300 flange have?
20 bolts of 1-1/8 inch diameter in 1.25 inch holes on a 514.4 mm bolt circle.
What is the thickness of a 14 inch Class 300 flange?
The minimum flange thickness is 52.4 mm, including the 1.6 mm raised face.
Last updated 2026-11-02