Saddle Design - PV Elite 2013 and Zick Analysis

[Alessandro87]

Dear All,

I am designing different Horizontal Vessels and I have to position and design 2 horizontal Saddles.

I am following Zick Analysis Method described in ASME VIII div 2 and I choosing typical saddle dimensions as already included into PV ELITE Software according to Dennis Moss Design Book.

My concern about design is :

When I select my Saddles (typical saddle width b= 250 mm and Wear Plate Width= 300 mm ) I can see that saddles are never verified if I consider the vessel full of the storaged liquid.

If I analyse the Vessel empty the saddle are always verified.

As per what I think, Vessel should be always verified full of the storaged liquid.For a separator (D=3m L=14 m Pdesign= 35 bar, wall thickness 35 mm )with a saddle width of 300 mm I would need a wear plate width of 650 mm.
Never seen a saddle like this on books.

Do these numbers are realistic ?
I am not so confident in them even though formulas are the one of Zick method.
If I use a smaller wear plate width, Software doesn't consider it and keep on with its calculations considering the minimum wear plate thickness that Vessel would have needed according to Asme.

How you manage these kind of problems?

Thanks for support!

 

[gr2vessels]

The 650 mm wearplate for this vessel doesn't sound too large. Obviously, it also depends on how close they are to the weld line of the head to the shell (check with Zick analysis, but also with Moss's book). As far as full of liquid not being considered, you need to check your input, because PV Elite is calculating the operating case with wind and seismic load, applied on the saddles. Check your input on the selecting the evaluation mode or design mode. You can 'play' with location and size only in evaluation mode.
Finally, you have doubts, ask for help in the PV Elite forum, once in a while you might get lucky and someone or even the PV Elite's gurus might give you a specific help if you provide the design file.
Cheers,
gr2vessels