Cycles N / Factor f 1

[robinxie]

Hello, everyone,
This question comes in my mind today suddenly.
According to B31.3, if SE<SA, the piping system could pass the displacement stress analysis.
SA=f(1.25Sc+0.25Sh) or SA=f(1.25(Sc+Sh)-SL)
Either of those two equations depends on Factor f, or say, Cycles N.
Let's assume there are two exactly same piping systems (same geometry, same pressure, same temperature). The cycles of ths first one is 7000, f=1.0. It could pass the stress analysis. The cycles of the other is 150000, f=0.5, so the SA is only half of the first one, and it may not pass stress analysis.
But when I use programs for stress analysis (CAESAR II, or something else), I just input geometry, pressure, temperature, etc. I never specified N or f.
What's the problem here?

Thanks ahead.

 

[richay]

Actually "f" is an input value in CAESAR II. The field for "f" is right next to the "Sh" (hot allowable) field.

F1 goes with SH1
F2 goes with SH2
:
:
F9 goes with SH9

Richard Ay
COADE, Inc.

 

[DSB123]

Suggest you READ the manuals for the pipe stress analysis software to understand the requirements for performing a stress calc. Allowable Stress values (where f is used to calculate the stress allowable) or the actual f value are requested by all pipe stress software packages. If you never specified N or f your calcs could be incorrect unless f=1.0 (default). Remember garbage in = garbage out when using software.

 

[robinxie]

Thanks all of you. Is anyone familiar with ADLPIPE? and how to specify f or N in ADLPIPE?

 

[pipesRus]

The 'f' factor is an input factor in ADLPIPE as it should be with all pipe stressing software. It is part of the code instruction and can be specified interactively when creating the load cases using the new ADLPIPE.Pro version.