We generally get the project specific allowable piping load data which we consider shell to nozzle local load analysis.

Shall we consider these piping loads on process nozzle as the loads & moment on the vessel at that location and consider their effect in wind & seismic.
If wer follow this procedure then seismic shear & moment increase almost by 100%.

Please guide me in this matter and let us know whether we should take the effect of piping loads in wind & seismic.
If not, let me know the reason behind not considering the allowable piping load data in seismic design.

Regards,
Bipin Balpatki

Hello Bipin

If I understand you correctly you are asking a question about the piping loads when a seismic event occurs. The simple answer is that you cannot compute those loads, it is too complex and far beyond the capabilities of PV Elite. It is hoped that the flexibility of the attached pipe work can accommodate the extra load. If the piping analysis were done using a programme such as Caesar II, you can get the seismic loadings from the piping engineer.

If you have a standard set of loads given to you by the purchaser, you have no way of knowing if they include wind and seismic loads.

Bipin,

You asked,

"Shall we consider these piping loads on process nozzle as the loads & moment on the vessel at that location and consider their effect in wind & seismic.

If we follow this procedure then seismic shear & moment increase almost by 100%."

Did they give you allowable loads in categories, as sustained, expansion and occasional, if not then ask for the loads in categories or separate them based on your experience and agreement with customer.

In my opinion, the typical operating piping loads can occur along with wind or seismic condition.

Hello Mandeep,

Thanx fopr the prompt reply.

Just one clarification is Piping load i referred is allowable nozzle load which client provide as project specification and it is not from piping group, so we will consider it as sustained load while doing the WRC.

Do you mean to say we should ask the piping group to give operating piping load along with wind and seismic and the same we sould apply on the vessel as force & moment & consider their effect in wind or seismic.

If yes then these loads will come from piping very late that is why i have asked you the method to take care of piping loads in the foundation load data in advance.

Regards,

Bipin

Hi Bipin,

Yes, I understand that.

Modeling it as sustained is the most conservative and safe option.

If you look in the AS 1210 (Australian pressure vessel code) they also have standard piping loads and they assume that 60% of loads are from thermal expansion of piping and 40% of loads are from weight etc (Sustained).

If you can categorize the loads you may be able to get higher allowables.

You may use an assumption like that, but do get approval from your client and document it.

This is my opinion, what you decide is your own decision.