Hi,

Could anyone explain the possible sources of axial restraint load at a line stop on a pipe rack during a sustain case?

I am getting a result that during operation case (temp @93 deg) axial load @ line stop is about 90 kN where at sustain case, the report is showing 150 kN.

I believe the axial load at line stop is driven by the thermal effect and not sure where this high load is coming from during a sustain case (no thermal considered).

No that with the line stop removed, the same location is shown to be displaced about 0.2 mm in axial direction during the sustain case.

If this is a B31.3 analysis, is it "sustained" or "alternate sustained"?
I agree that the weight analysis usually does load up non-weight-carrying line stops. (I assume you are not providing this stop on a vertical run of pipe.) But if this is an ALT-SUS case, the support configuration is set by their status in the associated operating state and that may be how you achieved such a large weight load.

I suggest providing something that we can look at. But here are two stabs in the dark.

If a pipe span has sufficient sag, it will draw the ends, though I'm given to understand CAESAR does not consider this case.

If a pipe is able to rotate about a vertical support, it can transform vertical motion into horizontal load.

In both cases, I would check supports to make sure there aren't any accidental gaps.

Do a quick check in the listing sections of the input to ensure no expansion joints or forces were input by error or a carryover from a "seed" file. Also check Bourdon options in the config/environment. Trying to rule out pressure effects on the model. As Michael mentioned a snapshot of the model may help. Also an oddball friction or density ... should be checked. Just some thoughts.

Hello,

Just a guess. Maybe it's a friction driven load. What's the pipe size and is it liquid inside the pipe?. Check your pipe thickness and all the basic input first. You can try to re-model from scratch. Are there any special components in your model. Check your boundaries also. Sometimes when I want to troubleshoot a model I will start from simple model first and check each result as I input more information in the model. Maybe in this way you can track which is causing that 150KN sustained.
Anyway, as everybody suggested it's better if you give more info. of your piping system.
I'm also interested to know what's causing that huge load in sustained in the axial direction.

Cheers!!