Pressure-Temperature
Rating Chart
Flange pressure classes and maximum working pressures per ASME B16.5 (A105 Carbon Steel).
Flange Pressure-Temperature Rating Table
Flange Class Selector
Enter design pressure and temperature to determine the appropriate flange class.
| Temperature (°C) | Class 150 (bar) | Class 300 (bar) | Class 600 (bar) | Class 900 (bar) | Class 1500 (bar) | Class 2500 (bar) |
|---|---|---|---|---|---|---|
| -29 to 38 | 19.6 | 51.1 | 102.1 | 153.2 | 255.3 | 425.5 |
| 100 | 17.7 | 46.6 | 93.2 | 139.8 | 233.0 | 388.3 |
| 150 | 15.8 | 45.1 | 90.2 | 135.4 | 225.6 | 376.0 |
| 200 | 13.8 | 43.8 | 87.6 | 131.4 | 219.0 | 365.0 |
| 250 | 12.1 | 41.9 | 83.8 | 125.8 | 209.6 | 349.3 |
| 300 | 10.2 | 39.8 | 79.6 | 119.4 | 199.0 | 331.6 |
| 350 | 8.4 | 37.5 | 75.1 | 112.6 | 187.7 | 312.8 |
| 400 | 6.5 | 35.2 | 70.4 | 105.6 | 176.0 | 293.3 |
Technical Notes
- 1.Values are per ASME B16.5-2020, Material Group 1.1 (A105, A216 WCB, A515 Gr.70).
- 2.Different P-T values apply for stainless steel (316L, 304) and alloy steel flanges.
- 3.Pressures shown are Maximum Allowable Working Pressure (MAWP). Hydrostatic test pressure is 1.5x MAWP.
- 4.Flange class selection must consider both design pressure and temperature together. Cannot select based on pressure alone.
- 5.1 bar = 14.5038 psi = 0.1 MPa. Approximate: Class 150 ≈ PN 20, Class 300 ≈ PN 50.
* Source: ASME B16.5-2020, Table 2-1.1. Current standard must be used for design.
For Correct Flange Class Selection
Consult our expert team for flange supply matching your project's pressure and temperature conditions.
Get Technical ConsultationWhat is a flange pressure class (PN / Class)?
Pressure class states the nominal pressure a flange or fitting can withstand. There are two systems: European PN (Pressure Nominal, in bar — PN6, PN10, PN16, PN25, PN40) and American ASME/ANSI Class (lb — Class 150, 300, 600, 900). Rough match: Class 150 ≈ PN20, Class 300 ≈ PN50, Class 600 ≈ PN100. But the real allowable pressure drops with material and temperature — the class is a nominal value at a reference temperature.
PN and Class systems, pressure-temperature relationship
For flanges, valves and fittings, the pressure class standardizes the pressure a component can safely carry. Two parallel systems exist: • PN (EN 1092-1): nominal pressure in bar — PN6, PN10, PN16, PN25, PN40, PN63, PN100. • Class (ASME B16.5): dimensionless rating — Class 150, 300, 600, 900, 1500, 2500. There is no exact conversion between them; a rough match is Class 150 ≈ PN20, Class 300 ≈ PN50, Class 600 ≈ PN100. Critical point: a flange's real allowable pressure is not fixed — it drops as temperature rises (pressure-temperature rating chart) and depends on the flange material (e.g. A105 carbon steel is rated differently from stainless). That is why flange selection weighs pressure class + material + operating temperature together; the flange face (RF/FF/RTJ) and bolt pattern must also match.
ASME B16.5 Pressure-Temperature Ratings (A105/A216 WCB, bar)
| Temperature (°C) | Class 150 | Class 300 | Class 600 | Class 900 | Class 1500 | Class 2500 |
|---|---|---|---|---|---|---|
| 38 | 19.6 | 51.1 | 102.1 | 153.2 | 255.3 | 425.5 |
| 100 | 17.7 | 46.4 | 92.8 | 139.2 | 232.0 | 386.6 |
| 150 | 15.8 | 45.1 | 90.6 | 135.8 | 226.0 | 376.8 |
| 200 | 13.9 | 43.8 | 87.6 | 131.4 | 219.0 | 365.0 |
| 250 | 12.1 | 41.8 | 83.6 | 125.0 | 208.7 | 347.6 |
| 300 | 10.2 | 38.9 | 77.5 | 116.0 | 193.6 | 322.7 |
| 350 | 8.4 | 36.4 | 73.0 | 109.3 | 182.3 | 304.0 |
| 400 | 6.5 | 28.3 | 56.9 | 85.2 | 142.0 | 236.5 |
| 450 | 4.6 | 12.8 | 25.9 | 38.7 | 64.6 | 107.4 |
| 500 | 2.8 | 4.8 | 9.7 | 14.5 | 24.3 | 40.3 |
Values interpolated from ASME B16.5-2020 Table 2-1.1 for Group 1.1 materials. For exact ratings consult the standard.
Frequently Asked Questions
What Class does PN16 correspond to?+
PN16 has no exact ASME equivalent; the nearest is Class 150 (Class 150 ≈ PN20). Because dimensions and bolt patterns differ, PN and Class flanges are generally not bolted together.
How many bar does Class 150 withstand?+
Class 150 has a nominal rating of about 20 bar (≈PN20) at reference (ambient) temperature; but the allowable pressure drops as temperature rises. For A105, for example, it decreases noticeably at 400 °C. For the exact value, consult the ASME B16.5 pressure-temperature table.
Can PN and Class be converted?+
Only roughly: Class 150 ≈ PN20, Class 300 ≈ PN50, Class 600 ≈ PN100. Because physical dimensions and bolt holes differ, this is an 'approximate equivalence', not direct interchangeability.
Does pressure class change with temperature?+
Yes. The pressure class is a nominal value at a reference temperature; the real allowable pressure decreases as temperature rises. Each material group has its own pressure-temperature rating curve (ASME B16.5 / EN 1092-1).
What happens if operating temperature exceeds the pressure class rating?+
The allowable pressure decreases with rising temperature because material yield strength drops; exceeding the rated temperature at full pressure risks flange joint failure — always derate per the applicable ASME table.
Related Sectors
Other Tools
Related Blog Posts
Technical articles, guides and industry analyses
Flange Types Guide: The 7 Main Flange Types and How to Choose
We explain weld neck, slip-on, blind, socket weld, threaded, lap joint and orifice flanges — their construction, facing types (RF/FF/RTJ), pressure classes and selection criteria.
Steel Material Selection Guide for Petrochemical Plants
A guide to selecting the right steel material for petrochemical and refinery plants. Step-by-step material determination based on temperature, pressure, corrosion mechanisms, and ASTM standards.