Flange Pressure-Temperature Ratings — Companion Article

What this tool does

The page reads interim ASME B16.5 flange pressure-temperature ratings. It works two ways. Allowable pressure takes a material group, a class, and a temperature, and gives the allowable pressure. Class required takes a material group, a pressure, and a temperature, and gives the lowest stored class that meets them.

Eight material groups have a rating table: 1.1, 2.1, 2.2, 1.2, 1.9, 1.10, 1.15, and 2.3. The classes are 150, 300, 400, 600, 900, 1500, and 2500. The tables are stored in psig and °F.

The lookup runs in the browser and runs once when the page opens. Opening /tools-training/flange-pressure-temperature/ with no query shows Allowable pressure, Group 1.1, Class 150, at 100 °C.

When to use it

Use it when you have chosen a flange material group and need to know what a class allows at the design temperature. Use Class required when the design pressure and temperature are known and you want the lowest class that covers them.

Use it with the flange datasheet. The datasheet gives the flange dimensions for a class. This page gives the rating for that class. Neither page sizes the bolting or checks the gasket.

Inputs

1. Lookup: Allowable pressure, or Class required. The page opens on Allowable pressure.
2. Material group. The list reads Group 1.1, Group 2.1, Group 2.2, Group 1.2, Group 1.9, Group 1.10, Group 1.15, Group 2.3. The page opens on Group 1.1.
3. Class, for Allowable pressure: 150, 300, 400, 600, 900, 1500, or 2500. The page opens on Class 150.
4. Pressure and its unit, for Class required: bar(g), psig, or kPa. The page opens on 20 bar(g).
5. Temperature and its unit: °C or °F. The page opens on 100 °C.

The page writes the selection into the address, so a lookup can be shared. For example /tools-training/flange-pressure-temperature/?mode=allowable&group=1.1&class=150&temperature=100&tunit=F opens Group 1.1, Class 150, at 100°F. For Class required use mode=class with pressure and punit.

How it works

A Celsius temperature is converted to Fahrenheit before the lookup. The table is in °F.

At or below 100°F the page uses the Min. to 100°F row and says so. At a listed temperature it reads the stored cell. Between two listed temperatures it interpolates in a straight line between them and marks the result interpolated. Above the last listed temperature it stops. Extrapolation is not applied.

A blank cell means the class is not rated there. Interpolation does not cross a blank cell.

The rating is stored in psig and rounded to 0.1 psig. Kilopascals are psig times 6.895, the factor printed on the source page. Bar(g) is that kilopascal figure divided by 100. Both are labelled derived.

Class required converts your pressure to psig. It then reads each class from 150 upward at your temperature and returns the first class whose allowable pressure is at least your pressure.

Understanding the result

The first line names the group and the catalogue entry. A tabulated result also shows the cell id, for example B16.5-PT-G1.1-CL150-T100F. An interpolated result has no id, because it is not a stored cell.

Temperature used is the Fahrenheit figure the lookup read. For a Celsius entry this is the converted value.

The answer line reads, for example, Class 150 allowable 19.651 bar(g) (285 psig, 1965.1 kPa). tabulated. On Class required it reads Class 300 is the lowest stored class at or above 300 psig, then gives that class’s allowable.

The page lists the materials shown with the group. Warnings follow. They say when the Min. to 100°F row was used, when a result is interpolated, and when the source chart marks the temperature. Group 1.1 is marked from 800°F. Groups 2.1 and 2.2 are marked from 1000°F. Some groups also carry a note on how the table was checked against a second publisher.

Engineering considerations

Pick the group from the flange material, not the pipe material. Groups shown, with the materials the page lists:

• 1.1: A105, A350 Gr. LF2, A216 Gr. WCB, A515 Gr. 70, A516 Gr. 70.
• 2.1: A182 Gr. F304, A182 Gr. F304H, A351 Gr. CF8, A240 Gr. 304.
• 2.2: A182 Gr. F316, A182 Gr. F316H, A351 Gr. CF8M, A240 Gr. 316, A182 Gr. F317.
• 1.2: A350 LF6 Cl. 2, A216 WCC, A352 LCC, A352 LC2, A352 LC3, A203 Gr. B, A203 Gr. E.
• 1.9: A182 F11 Cl. 2, A217 WC6, A387 Gr. 11 Cl. 2.
• 1.10: A182 F22 Cl. 3, A217 WC9, A387 Gr. 22 Cl. 2.
• 1.15: A182 F91, A217 C12A, A387 Gr. 91 Cl. 2.
• 2.3: A182 F304L, A182 F316L, A182 F317L, A240 304L, A240 316L.

Celsius entries are converted, then interpolated. 38 °C is 100.4°F, so Group 1.1 Class 150 at 38 °C gives 284.9 psig, interpolated, not the 285 psig cell. Enter 100°F, or 37.7 °C or below, to read the Min. to 100°F row.

The default view is 100 °C, which is 212°F. Group 1.1 Class 150 there is 256.4 psig, 17.679 bar(g), interpolated between 200°F and 300°F. Do not read it as the cold rating.

The Min. to 100°F row does not set a minimum temperature. The minimum temperature depends on the material. Check impact test requirements separately.

The rating is the flange rating only. The joint also depends on the bolting, the gasket, and the piping loads.

Group 2.3 stores an 850°F column. One publisher notes that A182 F304L is not to be used over 800°F, and another says the 850°F column applies to 316L and 317L only. The page shows that note with the result.

Example

Group 1.1, Class 150, 100°F. Tabulated. Id B16.5-PT-G1.1-CL150-T100F. Allowable 285 psig, 1965.1 kPa, 19.651 bar(g). The page notes that the Min. to 100°F row was used.

Group 1.1, Class 150, 150°F. Interpolated between 100°F and 200°F. Allowable 272.5 psig, 18.789 bar(g). No id.

Group 1.1, Class 150, 100 °C, the view a direct visit shows. Temperature used 212°F. Allowable 256.4 psig, 1767.9 kPa, 17.679 bar(g), interpolated between 200°F and 300°F.

Class required, Group 1.1, 300 psig at 100°F. Class 150 allows 285 psig, which is less. Class 300 allows 740 psig. The answer is Class 300.

Class required, Group 1.1, 20 bar(g) at 100 °C, the default pressure. At 212°F Class 150 allows 17.679 bar(g), which is less. The answer is Class 300, allowable 46.679 bar(g) (677 psig, 4667.9 kPa), interpolated.

Group 1.2, Class 150, 100°F. Allowable 290 psig, 19.996 bar(g). The note on this group records that Wermac prints 19.8 bar for that cell. The stored figure is the PipeData psig cell.

Group 2.3, Class 150, 100°F. Allowable 230 psig, 15.859 bar(g). The note records that Service Metal prints the same psig at every temperature in this table.

Standards/references (licensed vs interim)

The ratings are interim data from public sources, pending the licensed standard.

The note on the page reads: Interim data from Texas Flange ASME B16.5 pressure-temperature tables and PipeData group tables, not licensed ASME text. Verify against the current edition of ASME B16.5 before use.

Groups 1.1, 2.1, and 2.2 are the Texas Flange tables. Groups 1.2, 1.9, 1.10, 1.15, and 2.3 are the PipeData tables. Wermac and Service Metal are named in the group notes as cross-checks only. A citation of a standard number is not a copy of the standard. This article does not reproduce the tables. These interim figures will be replaced by licensed ASME data when it is available.

Limitations/disclaimer

The page is a rating lookup. It does not design a joint and it does not replace ASME B16.5.

• Groups 1.3, 1.4, 1.5, 1.7, 1.11, 1.13, 1.14, 1.17, 1.18, and 2.4 to 2.13 are named on the source material list and have no rating table here. They are not in the group list.
• Groups 1.1, 1.2, 1.9, 1.10, and 1.15 run to 1000°F. Groups 2.1 and 2.2 run to 1500°F. Group 2.3 runs to 850°F. Above the last row the page stops.
• Class 150 in Groups 2.1 and 2.2 is blank from 1050°F. The page does not rate it there.
• For Groups 1.2, 1.9, 1.10, and 1.15, PipeData says its Class 400 row rests on a single secondary source. For Group 1.2 the same applies to the columns from 850°F to 1000°F.
• Interpolated results are not tabulated cells. The page marks them.
• Kilopascal and bar(g) figures are derived from psig.
• The page does not check minimum design metal temperature, bolting, gaskets, or external loads.

Use the tool

Calculate now: Flange pressure-temperature ratings

Related tools

• Flange datasheet for the dimensions and studs of the class you choose. Read the flange datasheet companion article.
• Gaskets and RTJ rings for the gasket at the same class and NPS. Read the gaskets companion article.
• Wall thickness for the pipe wall at the design pressure. Read the wall thickness companion article.
• Unit converter for a factor between pressure or temperature units. Read the unit converter companion article.

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