Creep equation in EN13480-3

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r2user
Beiträge: 144
Registriert: Mi 14. Sep 2011, 10:18

Creep equation in EN13480-3

Beitrag von r2user »

How do you account for the equations of creep ie. 12.3.5-1
12.3.5 Additional conditions for the creep range
For piping operating within the creep range, the stresses, σ5, due to calculation pressure, pc, resultant moment,
MA, from weight and other sustained mechanical loadings, and to resultant moment, MC, from thermal expansion
and alternating loadings, shall satisfy the following equation:

S5=p*d/4e + 0.75 i Ma/Z +075 i MC/3Z < fcr

In equation (12.3.5-1), one-third of the moment MC shall be considered with respect to the material behaviour in the
creep rupture stress range, unless confirmed otherwise by detailed inelastic analysis.
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rohr2support
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Registriert: Mi 14. Sep 2011, 08:23

Re: Creep equation in EN13480-3

Beitrag von rohr2support »

HI
r2user hat geschrieben:How do you account for the equations of creep ie. 12.3.5-1
Whenever you specify a design temperature for a pice of pipe which is in the creep range (means that you have specified creep
rupture strength values for this temperature) Rohr2 will create a S5 equation (if you are in the automatic mode for equation creation).
If only parts of the system are in the creep range, only this part will be evaluated.

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r2user
Beiträge: 144
Registriert: Mi 14. Sep 2011, 10:18

Re: Creep equation in EN13480-3

Beitrag von r2user »

Dear Support Team

Thank you for your reply. I still have a problem with my model.
Basically i have two different lines. One is X10Crw of 94.5mm thickness. Second is 13CRMO4-5 of 30.8mm thickness.
In creep stress result, the colour plot is not showing for 13Cr material (here the pipe thk is only 30.8mm).

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rohr2support
Beiträge: 455
Registriert: Mi 14. Sep 2011, 08:23

Re: Creep equation in EN13480-3

Beitrag von rohr2support »

Hi

If a material is not in the creep range (e.g. the design temperature is so low that no creep rupture strength
is specified) then Rohr2 will not do the evaluation of the S5 equation.
If you have more than one material or design temperatures in the file, it may be that rohr2 generates an S5 equation
but evaluates it only for the sections which are in the creep range.

If Rohr2 would evaluate the whole system with the S5 equation you may get overstresses in
the S5 equation at pipe elements which are not even in the creep range!

Best regards
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