Flange standards — dimensions, ratings and tolerances for ASME, JIS and EN
A flange only fits if the mating flange, gasket and bolts come from the same standard family. These pages carry the published dimension tables and reference data for the four standards we machine most often: ASME B16.5, ASME B16.47 Series A and B, JIS B2220 and EN 1092-1.
Every size and rating links to its own specification page with outside diameter, thickness, raised face, bolt circle, bolt count, hole diameter and approximate weight. Tables are compiled from published standards data — verify against the edition named in your purchase specification before quoting a critical part.
North America, Middle East, South-East Asia
ASME B16.5
ASME B16.5-2025
- Sizes
- 1/2″–24″
- Ratings
- Class 150 · Class 300 · Class 400 · Class 600 · Class 900 · Class 1500 · Class 2500
- Size pages
- 382
Open dimension tables →
North America, Middle East
ASME B16.47 Series A
ASME B16.47-2025, Series A
- Sizes
- 26″–60″
- Ratings
- Class 150 · Class 300 · Class 400 · Class 600 · Class 900
- Size pages
- 168
Open dimension tables →
North America, Middle East
ASME B16.47 Series B
ASME B16.47-2025, Series B
- Sizes
- 26″–60″
- Ratings
- Class 150 · Class 300 · Class 400 · Class 600 · Class 900
- Size pages
- 168
Open dimension tables →
Japan, Korea, South-East Asia, marine and shipbuilding
JIS B2220
JIS B2220:2012
- Sizes
- 10A–600A
- Ratings
- 5K · 10K · 16K · 20K · 30K
- Size pages
- 330
Open dimension tables →
Europe, UK, Middle East, Africa, CIS projects
EN 1092-1
EN 1092-1:2018
- Sizes
- DN10–DN600
- Ratings
- PN6 · PN10 · PN16 · PN25 · PN40
- Size pages
- 300
Open dimension tables →
Reference library
Beyond dimensions: ratings, materials, tolerances and marking
A dimension table tells you whether a flange fits. These pages answer the next questions — how much pressure the part holds at your design temperature, which material group it belongs to, what tolerance applies and what must be stamped on the rim. Each table is transcribed from the named standard edition, with the table number and verification date shown.
Start with the ASME vs EN vs JIS comparison if you are checking whether two flanges bolt together, or read how to obtain the standards legally.
Class, PN and K ratings are not interchangeable
Buyers often ask whether a Class 150 flange can be replaced by a PN16 or 10K flange. They are similar in pressure duty, but the outside diameter, bolt circle, bolt count and hole size are set by the standard family, not by the pressure alone. A PN16 flange will not bolt to a Class 150 flange, and a JIS 10K flange will not bolt to either — even when the nominal size is written the same way.
The table below is a budgetary comparison only. Use it to shortlist a standard, then read the actual dimension table for the size you need before ordering flanges, gaskets or bolts.
| ASME class | Approx. PN | Approx. JIS | Typical service |
|---|---|---|---|
| ASME Class 150 | PN20 | 5K / 10K | General low-pressure piping |
| ASME Class 300 | PN50 | 10K / 16K | Medium-pressure process lines |
| ASME Class 400 | PN64 | 16K | Between Class 300 and 600 |
| ASME Class 600 | PN100 | 16K / 20K | High-pressure process and steam |
| ASME Class 900 | PN150 | 20K / 30K | High-pressure and severe service |
| ASME Class 1500 | PN250 | 30K | Very high pressure |
| ASME Class 2500 | PN420 | — | Extreme pressure, small sizes |
Ratings also depend on material group and temperature. For the pressure–temperature values, read the standard's rating tables — the comparison above never replaces them.