Effect of Wind Loading on Vertical Vessel Nozzles 1

[Ed555]

We have been provided with the piping loads from the skid manufacturer and are asked to calculate the nozzle loading on the vessel shell. This is for a 6.625" OD vessel on legs with 2 flanged nozzles. The specification calls for wind calculations. I assume that the wind loading on the vessel should be translated to moments and forces on the individual nozzles and added to the customer supplied piping loads. Is this typical?

Is there a simple way to calculate the forces and moments at the nozzle flanges or is it typically done using FEA? I have tried to model the vessel as a cantilevered beam but I believe this would be an indeterminate type. I am confused on if the flanges and base constraints should be fixed or free to rotate? Is there any assumptions I could use to simplify the problem?

Does anyone have a similar hand calculation I could review to get an idea on how to model the vessel? I assume it is a basic statics problem using a free body diagram.

 

[JStephen]

I would include additional projected area and/or roughness to allow for attached piping in the overall vessel loads for overturning, etc., but would not be too concerned about how the loads got transferred to the vessel.
For nozzle evaluation, I would assume that if wind loads on piping were significant, they would be included in the specified nozzle loads furnished by the piping designer.
You could complicate this problem a lot, but I don't know that you'd gain any actual accuracy in the design by doing so.

 

[SnTMan]

You got that right

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

Take into consideration how small bore piping branches fail. It is always vibration that is induced by one or more of:

1) Nearby pumps and motors (mechanical);
2) Flow-induced vibration (internal fluid);
3) Wind-induced vibration or 'flutter' (external fluid).

You have asked about the last case (I've probably missed some others). It occurs less often than 1) and 2).

Vibration in small-bore cantilevers is not a matter of transferring load from one point to another, but is a problem of natural frequency oscillation induced by very low forced vibration.
Fortunately there are a variety of mitigations available. Bracing between the branch and the run is usually my first recommendation, but it depends on the geometry.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[r6155]

Ed555
I consider this to be a general spec for PV, but not practical for your MINIATURE PV
I saw calculations for horizontal PV (Zick method) d= NPS 8 and LT-LT = 10” - Ridiculous!

Regards

 

[Ed555]

I would include additional projected area and/or roughness to allow for attached piping in the overall vessel loads for overturning, etc., but would not be too concerned about how the loads got transferred to the vessel.
For nozzle evaluation, I would assume that if wind loads on piping were significant, they would be included in the specified nozzle loads furnished by the piping designer.
You could complicate this problem a lot, but I don't know that you'd gain any actual accuracy in the design by doing so.

Thank you.

So basically whatever loads the skid manufacturer provides is what the vessel manufacturer will use for the nozzle loading calculations? The wind and seismic loading is typically only used to determine the vessel mounting requirements?