What is a flange pressure-temperature rating?

A flange P-T rating defines the maximum allowable working pressure at a specific temperature for a given flange class and material group. As temperature increases, the allowable pressure decreases.

What flange classes are defined in ASME B16.5?

ASME B16.5 defines seven pressure classes: 150, 300, 600, 900, 1500, and 2500. Each class has specific P-T ratings that vary by material group.

How does temperature affect flange ratings?

As temperature increases, the material strength decreases, which reduces the maximum allowable pressure. The P-T tables in ASME B16.5 account for this by providing pressure limits at various temperature steps.

What is material group 1.1 in ASME B16.5?

Group 1.1 covers carbon steel materials such as A105, A350 LF2, and A516 Gr.70. It is the most commonly used material group for general-purpose flanges.

Can I use ASME flanges with EN piping?

While ASME B16.5 and EN 1092-1 flanges have different dimensions and rating systems, adaptor flanges exist. However, mixing standards requires careful engineering review of both pressure ratings and dimensional compatibility.

Free Engineering Tool

Flange Pressure–Temperature Rating

Determine the maximum allowable working pressure for flanges per ASME B16.5. Select material group, class, and operating temperature.

ASME B16.5 EN 1092-1 Class 150–2500

Standard

Material Group

Flange Class

Operating Temperature (°C)

Operating Pressure (bar g) — optional check

Quick presets

Results

Max Allowable Pressure at Temperature

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Flange Class

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Material Group

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Operating Temperature

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Pressure Check

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Pressure-Temperature Rating Concept

ASME B16.5 provides pressure-temperature ratings for flanges in classes 150, 300, 600, 900, 1500, and 2500. The maximum allowable working pressure decreases as temperature increases, since material strength reduces at elevated temperatures.

Material Groups

Group	Materials	ASTM Specs
1.1	Carbon Steel	A105, A350 LF2, A516 Gr.70
1.2	Carbon Steel (Normalized)	A350 LF6 Cl.1
2.1	18Cr-8Ni Stainless	A182 F304, A240 304
2.2	16Cr-12Ni-2Mo Stainless	A182 F316, A240 316
2.3	Low-Carbon Stainless	A182 F304L, F316L
3.1	1¼Cr-½Mo Alloy	A182 F11 Cl.2

⚠️ Note: This calculator provides reference values. Always verify against the full ASME B16.5 or EN 1092-1 tables for critical applications. Values are interpolated between temperature steps.

Flange Pressure-Temperature Rating | ASME B16.5 / EN 1092

Published by Nikolai Shelkovenko on February 15, 2026 February 15, 2026

Results

Pressure-Temperature Rating Concept

Material Groups