Pressure Ratings & Pipe MAWP

ASME B16.5 flange pressure-temperature ratings and B31.3 pipe maximum allowable working pressure calculators

The ASME B16.5 standard defines pressure-temperature ratings for flanged fittings in 24 material groups covering carbon steel, alloy steel, stainless steel, and nickel alloys. Each group’s rating table shows the maximum allowable non-shock working pressure at elevated temperatures for seven flange classes (150 through 2500).

The pipe MAWP calculators compute the maximum allowable working pressure for seamless pipe per ASME B31.3-2024. Select a pipe material, schedule, and temperature to see the MAWP based on the straight pipe formula using allowable stresses from Table A-1.

Flange & Pipe Pressure Report
Select a flange class and pipe schedule to generate a side-by-side pressure comparison for your specification.
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B16.5 Flange Ratings by Material Group

Group 1 — Carbon & Alloy Steels

B31.3 Pipe MAWP Calculators

Stainless Steel (SS)

Nickel Alloys (Ni)

Flange Group ↔ Pipe Material Cross-Reference

Flange GroupDescriptionPipe Materials
Group 1.1Carbon SteelA106 Gr. B, A53 Gr. B
Group 1.2Alloy Steel C-Mn-SiA333 Gr. 6
Group 1.3Alloy Steel C-SiA106 Gr. A
Group 1.5Alloy Steel C-½MoA335 P1
Group 1.7Alloy Steel Cr-MoA335 P2
Group 1.9Alloy Steel 1¼Cr-½MoA335 P11
Group 1.10Alloy Steel 2¼Cr-1MoA335 P22
Group 1.13Alloy Steel 5Cr-½MoA335 P5
Group 1.14Alloy Steel 9Cr-1MoA335 P9
Group 1.15Alloy Steel 9Cr-1Mo-VA335 P91
Group 2.1Austenitic SS 18Cr-8NiA312 TP304
Group 2.2Austenitic SS 16Cr-12Ni-2MoA312 TP316
Group 2.3Austenitic SS L-GradeA312 TP304L, A312 TP316L
Group 2.4Austenitic SS 18Cr-10Ni-TiA312 TP321
Group 2.5Austenitic SS 18Cr-10Ni-CbA312 TP347
Group 2.7Austenitic SS 25Cr-20NiA312 TP310S
Group 3.1Alloy 20 (35Ni-35Fe-20Cr-Cb)B729 N08020
Group 3.2Nickel 200 (99.0Ni)B161 N02200
Group 3.3Nickel 201 Low-C (99.0Ni)B161 N02201
Group 3.4Monel 400 (67Ni-30Cu)B165 N04400
Group 3.5Inconel 600 (72Ni-15Cr-8Fe)B167 N06600
Group 3.7Hastelloy B2 (65Ni-28Mo)B622 N10665
Group 3.8Ni-Cr-Mo AlloysB622 N10276, B444 N06625, B423 N08825

References

  • ASME B16.5-2020 — Pipe Flanges and Flanged Fittings: NPS ½ Through NPS 24 Metric/Inch Standard
  • ASME B31.3-2024 — Process Piping
  • ASME B36.10M — Welded and Seamless Wrought Steel Pipe