What is ASME Section II-D allowable stress?

ASME Section II Part D tabulates the maximum allowable stress for code materials as a function of temperature. For Section VIII Division 1 and B31 piping, it is generally the lesser of yield- and tensile-based criteria at low temperature and time-dependent (creep) criteria at high temperature. The values fall as temperature rises, which is why design must use the allowable stress at the actual design temperature, not at ambient.

Why does the allowable stress differ between the 2019, 2021, and 2023 editions?

ASME revises Section II-D every two years. Some material lines get new data, corrected values, added temperature rows, or new grades. For most common materials the values are stable, but for some they shift between editions. Designing to the edition referenced by your construction code matters — this explorer lets you compare all three side by side.

How is the allowable stress at an intermediate temperature found?

ASME II-D publishes allowable stress at discrete temperatures. For a temperature between two published points, linear interpolation between the bracketing values is standard practice. This explorer interpolates linearly and flags when a requested temperature is outside the published range, where extrapolation is not code-valid.

What is a flange pressure-temperature rating?

ASME B16.5 assigns each flange a class (150, 300, 600, 900, 1500, 2500) and a material group. The maximum allowable working pressure for that class falls as temperature rises, tabulated per material group. When a material maps to a B16.5 material group, this explorer shows its P-T rating across all classes at the chosen temperature.

A P-Number (P-No) groups base materials with similar weldability so that welding procedure and performance qualifications can cover a range of materials at once. For example, most carbon steels are P-No 1. Filtering by P-No quickly narrows the database to a weldability-comparable family.

ASME Material Property Explorer | Allowable Stress vs Temperature (II-D 2019/2021/2023)

Loading material database… Click any row to open allowable stress & yield vs temperature, plus flange P-T ratings.

Material	Composition	P-No	Form	ρ (kg/m³)	SMYS (MPa)	SMTS (MPa)
Loading 9,000+ ASME II-D materials…

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Design temp (°F)

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Allowable Stress vs Temperature

Flange Pressure-Temperature Rating (ASME B16.5)

All values read from the SinaumeSync EngineeringDB (ASME Section II-D & B16.5). Intermediate temperatures are linearly interpolated between published points; temperatures outside the published range are flagged and are not code-valid. Always verify against the controlling code edition before use.

How to Read ASME Section II-D Allowable Stress (and Why the Edition Matters)

Allowable stress vs temperature · three code editions · flange P-T ratings · 5 FAQs

Most pressure-design mistakes don't come from the formula — they come from reading the allowable stress at the wrong temperature, or from a different code edition than the one the job is built to. The allowable stress, S, is the single value that controls how thick a pipe wall or vessel shell has to be, and it drops as the metal gets hotter. Use the ambient value for a 400 °C line and the wall comes out dangerously thin.

This explorer puts the entire ASME Section II-D material set in one place: search by specification, grade, or composition, then open any material to see its allowable stress and yield strength plotted against temperature — across the 2019, 2021, and 2023 editions at once. Where a material maps to a B16.5 flange group, it also shows the flange pressure-temperature rating for every class. Every number is traceable back to its source table.

At low and moderate temperatures, ASME bases the allowable stress on the material's yield and tensile strength with code safety factors. As temperature climbs, two things happen: the short-term strength itself falls, and above a threshold the material starts to creep — it deforms slowly under sustained load even below yield. In the creep range the allowable stress is governed by time-dependent criteria (typically tied to a target creep rate and to rupture strength with a safety factor), which is why the curve bends downward more steeply at high temperature.

The practical consequence: a carbon steel like SA-106 B holds roughly 17.1 ksi from ambient up to a few hundred degrees, then tapers as it approaches its temperature limit. Design at the actual metal temperature, never at ambient, and never extrapolate past the last published point — beyond that the code simply does not authorize the material.

ASME publishes Section II-D on a two-year cycle. Between editions, individual material lines can gain new temperature rows, get corrected values, add grades, or occasionally see an allowable stress revised up or down as new data is assessed. For the large majority of common materials the numbers are stable across editions — but "usually stable" is not "always," and a project is built to a specific code edition.

That is why this explorer shows all three editions together. Toggle "Compare all editions" on any material and the chart overlays 2019, 2021, and 2023 so a difference is immediately visible. If your construction code points to a particular II-D edition, read that column; if you are checking whether a legacy design still holds under a newer edition, the side-by-side answers it directly.

ASME B16.5 doesn't rate a flange by its exact alloy — it sorts materials into material groups (Group 1.1, 1.2, 2.1, and so on), and each group has a pressure-temperature table for every class from 150 to 2500. So the chain runs: pick a material spec and grade, find its B16.5 material group, then read the maximum allowable working pressure for the class at your temperature.

This explorer walks that chain for you. When a material maps to a B16.5 group (forging and plate specs like SA-105 do; many pipe specs do not, by design), the flange section lists the rating for all six classes at the design temperature you entered — the same 285 / 740 / 1480 psi family of Group 1.1 numbers you would otherwise hand-read from a B16.5 table.

It is the maximum stress ASME permits in a code material at a given temperature, tabulated in Section II Part D. It is the controlling input to wall-thickness and MAWP calculations, and it decreases as temperature rises.

A design is built to a specific edition. Values can change between 2019, 2021, and 2023 for some materials, so reading the right edition — and checking whether a change affects a legacy design — matters.

By linear interpolation between the two bracketing published points, which is standard practice. Requests outside the published range are flagged because extrapolation is not code-valid.

B16.5 P-T ratings apply to flange materials (forgings, plate, castings) that fall into a B16.5 material group. Many pipe-only specs don't map to a flange group, so no rating is shown — that is correct, not missing data.

No. It is a fast, traceable reference. Always confirm against the governing code edition and have qualified engineers verify any value used in design.

ASME Material Property Explorer

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How to Read ASME Section II-D Allowable Stress (and Why the Edition Matters)

Why Allowable Stress Falls With Temperature

Edition to Edition: 2019 vs 2021 vs 2023

From Material to Flange Rating

Frequently Asked Questions