How does the program calculate ASME B31.1 allowable values in AutoPIPE?
Open AutoPIPE, see the following AutoPIPE help section:
Help > Contents> Contents Tab> Reference Information> Code Compliance Calculations> ASME B31.1> select a code year, see the various topics,
Read the entire entry. Somewhere in the write-up will be information about how AutoPIPE calculates the various allowable values for the output report.
Note: there are some settings under Tools> Model Options> Results that may affect the Allowable value, confirm these values and take them into consideration when calculating the allowable(s).
Equation/Nomenclature
Location in AutoPIPE
σ = W∙SE; SE = Ej∙SH
W = Weld Joint Strength W factor
Insert/Modify > Pipe Properties
Ej = Weld Efficiency Factor
Tools > Model Options > Results
SH = Hot Allowable Stress
Insert/Modify > Operating Temperature and Pressure
Equation / Nomenclature
σ = k∙SH
k = k-factor
Tools > Combinations > “Code Comb.” tab
SH = Hot allowable stress
σ = SH
if SA > SE
σ = Sa
If SE> SA and SH> SL
σ = SA + f (SH - SL)
f = Range reduction factor
SA = expansion allowable stress.
Tools> Model Options> Results> Sustain Margin (Y/N/E)
if Sustain Margin = Y > SA = f(1.25SC+0.25SH)+f(SH-SL)
if Sustain Margin = N > SA =f(SC+0.25SH)
if Sustain Margin = E> SA= f (SC+0.25SH)
unless σ > SA, otherwise SA=f(1.25SC+0.25SH)+f(SH-SL)
f = Range Reduction Factor
SC = Cold Allowable Stress
SL = Sustained Load
Taken from Sustained Load calculation
ASME B31.1 Piping Code Calculation Issues
Bentley AutoPIPE