Flange Pressure-Temperature Rating Lookup

Find the rated working pressure of an ASME B16.5 flange at any temperature. Choose the material group, enter the design temperature and, optionally, the design pressure, and the tool gives the rating for every class from 150 to 2500 by linear interpolation, flags the minimum class that satisfies the design pressure, plots the rating envelope and shows the full table for the group.

What it gives you

• Ratings for Classes 150, 300, 400, 600, 900, 1500 and 2500
• Groups 1.1 (carbon steel), 2.1 (304) and 2.2 (316, 316H, 317)
• Minimum class for a design pressure with the margin
• Rating envelope chart with the design point plotted
• bar/°C or psig/°F, CSV export of the table

Method and standards

The tables are transcribed from published extracts of ASME B16.5-2025 (Tables 2-1.1, 2-2.1 and 2-2.2) in US customary units and converted here. B16.5 permits linear interpolation between tabulated temperatures but not between classes. Ratings apply to the flange only: the gasket and bolting must be rated separately, and the joint is limited by the weakest of the three.

How to use it

1. Select the material group for your flange material.
2. Enter the design temperature, and the design pressure if you want the minimum class.
3. Read the rating cards and the highlighted row in the table.

Questions engineers ask

Why is Class 150 not rated above 538 °C?

The standard stops the Class 150 table at 1000 °F (538 °C). Higher classes in the stainless groups continue to 816 °C.

Are 316L and duplex included?

Not yet. Only groups with verified published tables are loaded; Group 2.3 (304L/316L) and the duplex groups will be added when the tables can be checked.

Do the bar values match the SI table in the standard exactly?

They are converted from the US table, so they can differ from the standard's separately tabulated SI values by up to about 0.2 bar.