How are temperatures between table rows handled?

The calculator applies linear interpolation between the nearest published temperature nodes in °C / bar.

What is hydrostatic shell test pressure here?

P_hydro = 1.5 × ambient rating (−29…38 °C band), not 1.5 × the derated elevated-temperature MAWP.

Does this cover ASME B16.47 large flanges?

No. Scope is ASME B16.5 NPS ½–24. Large-diameter flanges use B16.47 (not in Phase-1).

Which material groups are included in Phase-1?

Group 1.1 (A105 / A106-B / A350 LF2) and Group 2.2 (A182 F316 / F316L). Other Table 2 groups require a later data release.

ASME B16.5 Flange Pressure-Temperature Rating — Group 1.1 · Class 600 · 300 °C | FieldEngineersKit

1. Core Formula & Variable Definitions

ASME B16.5 — Pipe Flanges and Flanged Fittings (NPS ½–24) · ASME B16.5 Table 2 — Pressure-Temperature Ratings (Groups 1.1 & 2.2 Phase-1 extract) · ASME B31.3 (2022 Edition) · — Process Piping (related wall-thickness screening)

P = P₁ + ((T − T₁)/(T₂ − T₁)) · (P₂ − P₁)

P_hydro = 1.5 · P_ambient (−29…38 °C)

ASME B16.5 Table 2 Pressure-Temperature Ratings · Phase-1 Groups 1.1 & 2.2

Groups 1.1 · 2.2Classes 150–2500 (Phase-1)Hydro 1.5 × ambientScope B16.5 NPS ≤ 24

Working pressure is taken from ASME B16.5 Table 2 for the selected material group and flange class. Intermediate temperatures use linear interpolation between published nodes. Hydrostatic shell test pressure is 1.5 × the ambient (−29…38 °C) rating. Phase-1 data: Group 1.1 Classes 150–2500 and Group 2.2 Classes 150/300/600. Scope is NPS ½–24 (B16.5); B16.47 large-diameter flanges are excluded.

T (Design Temperature) — Metal temperature used to enter Table 2 (°C / °F).
P (Working Pressure Rating) — Maximum allowable working pressure from Table 2 (bar / psi / MPa).
P_ambient (Ambient Rating) — Table 2 rating for the −29…38 °C band.
P_hydro (Hydrostatic Shell Test) — 1.5 × ambient rating (screening).
Group (Material Group) — B16.5 material group (Phase-1: 1.1 carbon steel, 2.2 316/316L).
Class (Flange Class) — Pressure class designator 150 / 300 / 600 / 900 / 1500 / 2500.

2. Allowances, Tolerances & Standards

Use official ASME B16.5 tables for stamped design. This tool is a Phase-1 screening extract with linear interpolation.

Linear interpolationP between T₁ and T₂

When design temperature falls between published nodes, MAWP is linearly interpolated in °C / bar space.

Hydrostatic shell test1.5 × P_ambient

Screening hydrotest pressure uses the ambient (−29…38 °C) rating, not the derated elevated-temperature rating.

B16.5 size limitNPS ≤ 24

Larger flanges follow ASME B16.47 and are outside this calculator.

Class 150 high temperature> 538 °C / 1000 °F

Class 150 service above 538 °C requires confirmation against B16.5 notes and owner specification.

Quick Reference Lookup Table

ASME B16.5 Group 1.1 carbon steel MAWP (bar) — Class 150 / 300 / 600 scan chart
T (°C)	Class 150	Class 300	Class 600
−29…38	19.6	51.1	102.1
50	19.2	50.1	—
100	17.7	46.4	92.8
150	15.8	45.2	—
200	14.0	43.8	87.6
250	12.1	41.9	—
300	10.2	39.8	79.6
350	8.4	37.6	—
400	6.5	34.7	69.4
450	4.7	23.0	46.0
500	2.8	11.3	22.5
538	1.4	5.6	11.3

Values from the Phase-1 FEK extract of ASME B16.5 Table 2-1.1. Class 600 rows marked — use nearest published nodes with linear interpolation in the live calculator. Group 2.2 and Classes 900–2500 are available in the interactive tool.

3. Material & Code Limitations

Only Groups 1.1 and 2.2 are loaded. Additional Table 2 groups require a later data release.

Material Group	Temperature Range	Allowable Stress / Limit	Engineering Notes
Group 1.1 — Carbon Steel	−29…538 °C	Classes 150–2500	Typical specs: ASTM A105, A106 Gr.B, A350 LF2.
Group 2.2 — Stainless 316/316L	−29…538 °C	Classes 150 / 300 / 600	Typical specs: ASTM A182 F316 / F316L. Classes 900–2500 not in Phase-1.

Code Applicability & Safety Boundaries

Do not apply these ratings to ASME B16.47 Series A/B flanges.
Confirm edition year of the project B16.5 table before stamping MAWP.

4. Step-by-Step Worked Example

Field VerificationShow

Worked Example — Group 1.1 Class 150 @ 125 °C

Carbon steel Class 150 flange at 125 °C (between 100 °C = 17.7 bar and 150 °C = 15.8 bar).

Material group:1.1 (A105)Flange class:150Design temperature:125 °C

1

Locate bounding nodes

T₁ = 100 °C, P₁ = 17.7 bar; T₂ = 150 °C, P₂ = 15.8 bar.

Result:Bracket identified

2

Linear interpolation

P = P_{1} + \frac{( T - T _{1} )}{( T _{2} - T _{1} )} (P_{2} - P_{1})

P = 17.7 + (125−100)/(150−100)×(15.8−17.7) = 17.7 − 0.95 = 16.75 bar.

Result:MAWP ≈ 16.8 bar

3

Hydrotest pressure

P_{h y d r o} = 1.5 P_{ambi e n t}

P_ambient = 19.6 bar → P_hydro = 29.4 bar.

Result:P_hydro = 29.4 bar

Conclusion: Report MAWP ≈ 16.8 bar at 125 °C and hydrotest 29.4 bar. Confirm against the project ASME B16.5 edition before design acceptance.

5. Frequently Asked Questions & Technical References

Show

No. Class is a dimensionless designator. MAWP depends on material group and temperature per ASME B16.5 Table 2 (e.g. Group 1.1 Class 150 ≈ 19.6 bar at 38 °C, much lower at elevated temperature).