Load case for min. ambiant Temperature?

Hi,
In my current project, the ambient temp. of piping installation yard is T=21°C which I used it as the ambient temp. in CAESAR.
The max design temp. is T1=80°C (ΔT1=80-21=59°C) and the min. ambient temp. of plant is T2=-36°C (ΔT2=21-(-36)=57°C).
All load cases now are according to T1 which cause a bigger temperature variation.

Could anybody say me that I have to add any new load cases for T2 (since during plant shutdown it will be the case) or I’m in safe range now?

Kind regards.

you have to check at -36 c also by simply taking new file in that you have to take -36 as a ambient

L1: W+T1+(whatever else is operating case 1)
L2: W+T2+(whatever else is operating case 2)
L3: W+P?+(whatever else is considered a sustained force effect)
L4: L1-L2 (EXP)

L4 is your strain range. Not ambient to hot; not ambient to cold - but hot to cold. If using B31.3, read 319.2.3(b).

Dave, I am not sure I would do like you said.
What about to change case 4 as following?

L4: L1-L3 (EXP)
L5: L2-L3 (EXP)

Thank you.

Here's what B31.3 paragraph 319.2.3(b) says:
... "the algebraic difference between strains in the extreme displacement condition and the original (as-installed) condition (or any anticipated condition with a greater differential effect) remains substantially constant during any one cycle of operation. This difference in strains produces a corresponding stress differential, the displacement stress range, which is used as the criterion in the design of piping for flexibility."...
You are referencing "the extreme displacement condition and the original (as-installed) condition" and I am talking about "any anticipated condition with a greater differential effect".

Again, in my example T1 is above ambient and T2 is below ambient.

Thank you Dave.

Thanks Dave! it's very helpful.

Hi Dave,

There is a new issue in this modeling for checking the equipment nozzle loads.

This is the load cases:
L1: W+T1+P1 (OPE)
L2: W+T2+P1 (OPE)
L3: W+P1 (SUS)
L4: L1-L2 (EXP)

The model passed the "Code Stress" for the extreme displacement condition (L4).

Shall I check the loads applied to equipment nozzle for L2, which is the the min. ambient temp. of plant (T=-36°C), or only L1 as the max. design temp. (T1=80°C) will be enough?

Regards

You should check any condition which the nozzle can experience. Many times, by inspection, you can conclude that one particular load case is the worst condition for a given nozzle. However, if you can't draw this conclusion, it is prudent to check them all.

Thank you Richard.