American Standard – ASME B31.3:2012

Formula

The internal pressures are calculated by using the following formula:

P = (2 · tmin · S) / (OD - (2 · Y · tmin))

Symbol / Description
P Internal pressure (ksi)
tmin Min. wall thickness (mm)
S Allowable stress (ksi)
OD Nominal outside diameter (mm)
Y 0.4 for tmin < OD/6
Y (OD - (2 · tmin))/2 (OD - tmin) for tmin = OD/6

Attention: The pressures on these pages are given only as guidance. Dimensioning of piping systems also depend on other factors like external forces, thermal stresses, dead weight etc. Furthermore the design must be made according to regulations from local authorities and approved accordingly. For tubes in pressure vessels ASME section VIII division 1 and 2 may apply. The calculations are similar but the allowed stress has a different definition.

Values for allowed stress given in ASME B31.3 table A-1, are only valid for pipe unless otherwise stated! See also footnote *1).

ASTM/UNS 100°F
40°C
200°F
90°C
300°F
150°C
400°F
200°C
500°F
260°C
600°F
320°C
700°F
370°C
304L 16.7 16.7 16.7 15.8 14.7 14.0 13.5
304/304L 20.0 20.0 20.0 18.6 17.5 16.6 15.8
316L 16.7 16.7 16.7 15.7 14.8 14.0 13.5
316/316L 20.0 20.0 20.0 19.3 18.0 17.0 16.3
321:1 16.7 16.7 16.7 16.7 16.1 15.2 14.6
321:2 20.0 20.0 20.0 20.0 19.3 18.3 17.5
347 20.0 20.0 20.0 20.0 20.0 19.3 18.7
316Ti 20.0 20.0 20.0 19.4 17.8 16.8 16.2
S31500 26.3 25.4 24.4 24.2 24.2 24.2 24.2
S32304 29.0 27.9 26.1 24.7 22.9 19.2 -
S31803 30.0 30.0 28.9 27.8 27.2 26.9 -
S32750 38.7 36.3 34.8 34.0 33.9 33.9 -
N06600:1 16.7 16.7 16.7 16.7 16.7 16.7 16.7
N06600:2 20.0 20.0 20.0 20.0 20.0 20.0 20.0
N06600:3 23.3 23.3 23.3 23.3 23.3 23.3 23.3
N08800 CF 20.0 20.0 20.0 20.0 20.0 20.0 20.0
N08800 HF 16.7 16.7 16.7 16.7 16.7 16.7 16.7
N08904 20.3 16.7 15.1 13.8 12.7 11.9 11.4
N08028 20.7 18.9 17.7 16.5 15.4 14.4 13.6
S31254 26.9 26.9 21.4 19.8 18.6 17.9 17.4
N08825 23.3 23.3 23.3 23.3 23.3 23.3 23.3
R50400/R52400 16.6 14.4 12.0 10.2 8.8 - -
R50550 18.6 15.8 12.8 10.3 8.5 7.4 -
R56320 25.7 24.7 22.6 20.2 18.1 17.2 -
R53400 20.0 18.7 16.2 14.3 13.1 12.3 -
R60702 18.3 15.4 12.0 9.3 7.4 6.0 5.2

*1) Values for various product forms and applications are found in ASME section VIII division 1 and 2. Only in that standard, it is permitted, according to paragraph UG 15, to use values for a certain grade and product form also for other product forms of that grade when data is missing.
*2) A 312 and A 269 tube
*3) A 312, A 376 and A 269 tube
*4) A 312 and A 269 tube
*5) A 312, A 376 and A 269 tube
*6) t > 3/8" A 312 and A 376
*7) t < 3/8" A 312 and A 376
*8) A 312 and A 376
*9) Values according to ASME SA-240, table 1A, in ASME BPVC 2011. See *1) regarding paragraph UG 15.
*10) Values according to ASME BPVC IID 2011, table 1A, Tmax 750°F, seamless pipe SA-790 and seamless tube SA-789
*11) A 790 and A 789 seamless tube
*12) A 790 and A 789 seamless tube
*13) A 790 and A 789 seamless tube
*14) B 167 OD > 5" and hot finished
*15) B 167 OD < 5“ and hot finished + OD > 5" and cold finished
*16) B 167 OD < 5“ and cold finished
*17) B 407
*18) B 407
*19) Values from ASME BPVC section IID 2011, table 1B, seamless pipe and tube SB-677
*20) Values from ASME section IID 2011, table 1B, Tmax 850°F, seamless tube SB-668
*21) Values according to ASME SA-312, seamless pipe, table 1A in ASME BPVC IID, 2011
*22) Values according to ASME SB 423 seamless pipe and tube, cold drawn annealed, table A-1 in ASME B31.3, 2012

Titanium and zirconium tubes are produced in sizes 9.53 - 38.1 mm

*23) Values according to ASME SB 338*, seamless and welded tube, table 1B in ASME BPVC IID, 2011
*24) Values according to ASME SB 338, seamless tube and pipe, SB 861, table 1B in ASME BPVC IID, 2011
*25) Values according to ASME SB 338, seamless tube, and pipe, SB 861, table 1B in ASME BPVC IID, 2011
*26) Values according to ASME SB 338, seamless tube, and pipe, SB 861, table 1B in ASME BPVC IID, 2011
*27) Values according to ASME SB 523, seamless tube, and ASME SB 658, seamless and welded pipe, table A-1 in ASME B31.3, 2012

* Grades 2H and 7H

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