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zahirazam2009
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Horizontal PV Supports

10/11/2013 6:49 AM

why more than 2 saddle support is avoided in horizontal pressure vessel????

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PWSlack
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#1

Re: horizontal PV supports.

10/11/2013 6:50 AM

Well, if it had three supports, what happens if the ground under one of them gives way?

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MJCronin
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#2

Re: horizontal PV supports.

10/11/2013 7:08 AM

Zahirashazam,

Three or more saddles makes the overall structure statically indeterminate and therefore difficult to evaluate.

Additionally, because we have an excellent, empirically developed method (Zick) for evaluating stress levels of PVs on two saddles, we would like to stick with the method that works.

I am well aware of the fact that there are many vessels out there that have three or more saddles (mostly FRP and plastic vessels)...

You also should consider also what would happen to the structure if one of the end saddles deflects a tiny bit more than a center saddle. We would then have a cantilever pressure vessel and a whole new area of the vessel shell would be undergoing bending stresses !

This is my opinion only....

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ronclarke
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#3

Re: horizontal PV supports.

10/11/2013 8:43 AM

Different expansion rates along the length.

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ronclarke
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#6
In reply to #3

Re: horizontal PV supports.

10/11/2013 12:02 PM

Why? did i get an off topic. I have seen this situation in practice??????????

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passingtongreen
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#4

Re: Horizontal PV Supports.

10/11/2013 11:44 AM

In addition to the excellent replies above, with more than two supports, it is nearly impossible to level the supports with sufficient accuracy that they each have the correct apportioned load. With two supports, the problem doesn't exist.

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ronseto
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#5

Re: Horizontal PV Supports.

10/11/2013 11:54 AM

Imagine a chair or table with 6 legs.

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Tornado
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#7
In reply to #5

Re: Horizontal PV Supports.

10/11/2013 9:54 PM

But then, explain why many office chairs have five legs.

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Codemaster
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#8
In reply to #7

Re: Horizontal PV Supports.

10/12/2013 9:47 AM

And why does a milking stool have 3 legs? (because the cow's got the udder, if you didn't know)

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#9

Re: Horizontal PV Supports

10/13/2013 10:02 AM
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zahirazam2009
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#10

Re: Horizontal PV Supports

10/14/2013 11:39 PM

thank you all for clearing my doubt

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