Applying torsional moment to shell/support in PVElite

[imransaeed1804]

Hi,
I have a vertical vessel which has tangential nozzles. These nozzles are subjected to thrust load due to process reasons. This results in a torsional moment on the whole section of the vessel that also affects the support (skirt & base ring) of the vessel.
I tried adding moment to the shell in PVElite, by using the "Force/Moment Input", however, PVElite will not allow to enter a torsional moment (moment around the y axis, which is the vertical axis of the vessel). The moment field in y direction is greyed.
Any idea how can apply this torsional moment to the shell section? is there any workaround in PVElite? Intent is to transfer this moment to skirt as well.

Thanks.

 

[NovaStark]

I am not sure there is a specific way to do that on a shell.

AFAIK, the force/moments are calculated based on WRC107/537 which are really for the local effects of the attachment on the nozzle/shell. You may need to reach out to Hexagon for further advice.

 

[jt1234]

1. Torsion in 99% of cases will not produce significant stress on vessel body or even flange. Therefore it is negligible in flange rating or even in Appendix 2 analysis, and can be ignored in the vessel design including skirt. That is why no torsion input in PV Elite on the shell. If you want to check the torsional stress, just do a hand calculation, getting the formula from any text book or Roark's formula. You will be surprised how small the stress is.
2. The nozzle loading, is considered a local effect, so called "self constrained? " or other term used in code or design manual, such that it will not be considered to generate primary stress on the vessel wall. In other words, you do not need to think as structural members that all loading will be acting on each member. The local deformation will absorb the loading and will not propagate down to the skirt, as vessel is considered flexible by the ratio of t/D . However, we will consider its impact down to skirt only if the d/D is greater than 1/3 or nozzle and vessel are very rigid, can acting like structural members for pushing or puling. So check your d/D, and thickness.
3. The major concern is the local reinforcement at the opening. Converting loading correctly to WRC107 convention is the key, or use FEA.

 

[CuMo]

Go to the program settings and ask it to apply/resolve the nozzle loads to the supports.

It's in Job Specific Settings and is called "Conzider Nozzle Loads on supports".

Then add your nozzle loads and ensure Thrust loads are considered.

PV Elite will then resolve any nozzle loads as vectors and transfer them onto the vessel and support respectively. -> More information will be printed in the Warning and Errors section of the Output report.

Good luck!

 

[imransaeed1804]

Hi All,
Thanks for your replies.

@jt1234 Thanks for reminding me that. Agree that torsion generally results in less stress.

@CuMo Thanks, this is very helpful. I turns out that I am using an older version of PVElite which doesn't have this option. I need to upgrade to the latest version. Hopefully, this option will save me some time.


Imran