When evaluating piping loads and moments on a pressure vessel nozzle using WRC-107, should the nozzle pressure thrust be included as a radial load?

Regards
Shrikant
L&T

Shrikant,

If it is asked specifically in client's specification/datasheet, then pressure thrust is to be considered while evaluating local stresses in the vessel using WRCB-107. Otherwise there is no need to consider it.

Thanks.

Mukesh
www.theculminates.com
M: +91-9428500192

Hi folks

We need to be circumspect here. We should rather ask ourselves if there is a pressure thrust irrespective of what the client's specification sheet says. We should make an engineering judgment to consider what is really happening at the nozzle. Pressure thrust is usually small in comparison with the radial load so adding it will probably not make much difference.

Dear Ray,

Share with you a simple example to illustrate how harmful if pressure thrust load is added half way of engineering cycle.

Say there is a nozzle with ID around 22". Design pressure = 150 psig.

Pressure thrust = Pi * 22² (150)/4
= 57020 lbf

It is not really in-significant or not so much different. It is harmful on top of outward radial load and usually fail in WRC 107 analysis when shell wall is low. (Example above, if come along with 79" ID, zero CA, tr shell = 0.6")

We did face problem when customer seen PVElite report shown "Not Considered Pressure Thrust" and comment to add "Y" even though did not state on project specification and may not even know the right application of pressure thrust. It will be hard time for designer to explain/educate client's engineer. If PVElite report can remove printing of "Y/N of Pressure Thrust" but remain selection option in programme, it will be helpful to user where decision is still on user's mind but can avoid to triggle client's un-necessary comment to demand for it.

Thank you!

S K Tan

Hello SK

If you send the report to MS Word instead of directly to the printer, you can remove the reference to the pressure thrust not being used.