ASME B16.5 — find minimum class for design P & T, or find max allowable pressure for a given class.
Minimum required pressure class
Class 300#
Carbon Steel · A105, A181 Gr.60, A216 WCB/WCC, A350 LF1, A352 LCB/LCC
| Class | Max P (MPa) | Max P (bar) | Max P (psi) | Max P (MPa) | Status |
|---|---|---|---|---|---|
| 150# | 1.53 | 15.3 | 222 | 1.53 | FAIL |
| 300#Required | 5.03 | 50.3 | 730 | 5.03 | OK |
| 600# | 10.05 | 100.5 | 1458 | 10.05 | OK |
| 900# | 15.08 | 150.8 | 2187 | 15.08 | OK |
| 1500# | 25.14 | 251.4 | 3646 | 25.14 | OK |
| 2500# | 41.89 | 418.9 | 6076 | 41.89 | OK |
Group 1.1 — Carbon Steel · MPa gauge · Dashed blue lines = design point
Applicable size range
ASME B16.5 covers NPS ½ to NPS 24 (DN 15 to DN 600). For larger flanges (NPS 26 and above), refer to ASME B16.47 Series A (MSS SP-44) or Series B (API 605). Ratings differ significantly between series and flange class.
Flange rating ≠ pipe schedule rating
These P-T ratings apply to the flange. The connected pipe wall thickness must be separately verified per ASME B31.3 or B31.1. A Class 600# flange does not mean the connected schedule 40 pipe is rated to Class 600# pressure at that temperature.
Pressures in MPa gauge. Design temperature column highlighted.
| T (°C) | 150# | 300# | 600# | 900# | 1500# | 2500# |
|---|---|---|---|---|---|---|
| -29 | 1.96 | 5.11 | 10.21 | 15.32 | 25.54 | 42.57 |
| 38 | 1.96 | 5.11 | 10.21 | 15.32 | 25.54 | 42.57 |
| 100 | 1.79 | 5.11 | 10.21 | 15.32 | 25.54 | 42.57 |
| 150 | 1.64 | 5.11 | 10.21 | 15.32 | 25.54 | 42.57 |
| 200 | 1.53 | 5.03 | 10.05 | 15.08 | 25.14 | 41.89 |
| 250 | 1.43 | 4.80 | 9.61 | 14.41 | 24.01 | 40.02 |
| 300 | 1.38 | 4.57 | 9.13 | 13.70 | 22.83 | 38.05 |
| 350 | 1.38 | 4.33 | 8.65 | 12.98 | 21.63 | 36.04 |
| 400 | 1.31 | 4.04 | 8.09 | 12.13 | 20.22 | 33.70 |
| 425 | 1.27 | 3.88 | 7.76 | 11.64 | 19.40 | 32.33 |
| 450 | 1.24 | 3.73 | 7.46 | 11.19 | 18.65 | 31.08 |
| 475 | 1.21 | 3.58 | 7.17 | 10.75 | 17.92 | 29.87 |
| 500 | 1.13 | 3.36 | 6.73 | 10.09 | 16.82 | 28.04 |
| 538 | 0.95 | 2.71 | 5.42 | 8.13 | 13.55 | 22.58 |
Representative values based on published ASME B16.5-2017 data. Values for intermediate temperatures are linearly interpolated. All pressures are gauge pressures. Verify against current ASME B16.5 edition before use in design documentation. Minimum temperature for Group 1.1: -29 °C · Maximum: 538 °C.