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Structural qualities of PVC

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To keep it brief, I'll just fire off my design specs and answer questions if there are any.

I want to build a cylindrical pedestal to hold a heavy spherical object.

>The pedestal will be three feet tall, and about 12 inches in diameter
>The sphere on top will be an acrylic shell filled with water. It will weigh about 160 pounds when full!
>The whole assemblage must be semi portable (I will have access to a truck with a lift gate, hand trucks, carts and so forth. The sphere will only be filled with water once the pedestal is in place).
>Economy is important, but not the top priority.

Right now, a 12 inch PVC pipe seems like a quick, economical, lightweight way of getting a sturdy pedestal.

The question is, will a 12" PVC pipe bear the stress basically indefinitely? It's for a temporary installation, but if the pedestal cracked, it would be a complete disaster. Is it worth reinforcing it with bands of Sintra, or is the whole idea totally fucked?
PVC sucks for structural purposes.
What I would suggest is you look locally for any metals supply places, call them up and ask if they have anything suitable that they can cut to length for you. Sometimes they will have off cuts for cheap, or they may know some place else that might be helpful.

You can also ask around at welding supply shops if they know anywhere locally that would have this sort of thing.

If it was only 1/8" thick steel it would probably be okay (@12" across and with 160 lbs on it).
1/4" thick pipe that size would be ~80 lbs alone.
1/2" thick pipe that size is going to weigh a LOT. and kinda cost a lot too.
That's a shame, but I was half expecting I'd have to go for metal pipe instead. Thanks for the notes.
We used to use heavy gauge 2" waste PVC and a mesh sling to construct beach chairs before they were affordable. I have seen them withstand 250 lbs tourists flop down on them so depending on the construction you can do it.

While you have to build it, it would be cheap and quick but I wouldn't know the price in your area compared to steel.
Looks like a 3' section of schedule 40 pipe at 12" diameter will weigh about 160 pounds on it's own! I guess that will make it easier to build a stable base...

Anyone have a rough idea what that would cost? I know steel prices can fluctuate, but I'm curious about a ballpark price. If it's too high I may just give up the cylindrical pedestal altogether.
PVC has good strength, but not rigidity. So it won't be a problem unless you are trying to bridge it across a span. Resting something on top of a pvc column should not be a problem.

I think you are talking about taking a 12" diameter single piece of pvp pipe, and putting the sphere on the open end of that. It will be plenty strong if so. Just make sure the pedestal has a weighted, broad base so it doesn't tip over.
You are correct re: the position of the sphere (which will be about 20 inches in diameter).

I'm particularly concerned about the weight of the sphere pressing slightly outward on the open end of the pipe and cracking or bending enough for things to get all off balance and topple over.

And yeah, the basing is another issue on it's own, but I think I've got that side under control.
Another question--what type of PVC pipe would best suit my application? I assume foam core is right out. Schedule 80 maybe?
>structural qualities of PVC
shit and piss m8
Expect bowing and wobbling, and things generally coming undone at the slightest impact if you don't weld them together with some solvent or use plastic cement.
As long as PVC isn't 5x as long as it is wide, it won't be likely to bow from the sides. Just make sure that you have the pipe fixed very firmly to the base and for good measure twice as heavy as something you will be placing on top of it.
>Directly conflicting Info: Yes
Given that, I agree with you that the stress trying to split the pipe is worrisome. I would consider getting an iron or copper or brass fitting or coupling to cap the pipe with.
Fill the PVC pipe with Concrete and a 3' piece of rebar. That should do the trick. It'll be heavy as fuck with that water sphere shit on top, but use those carts, hand trucks and shit to move it into place.
>That's a shame, but I was half expecting I'd have to go for metal pipe instead. Thanks for the notes.
I've never bought anything this large--but here is some real numbers:

on this page--
they show that a piece of DOM steel tube, 12" diameter, 1/4" wall and 4 feet long, will cost $978 + shipping (truck freight). (and it would weigh about 130 lbs, but anyway)

1. these online cut-to-order places generally price their stuff AT LEAST 2X what local places will charge (and then paying for shipping makes it nearly 3X,,,). So if you could find someplace locally to get it, that will prolly knock the price down to around $500 or so.

2. that tube example is twice as thick as you need. so if you could find 1/8" thick tube, that would knock the price down to around $250, since the stuff is basically priced by the pound.

3. If you were buying an off-cut or salvage tube, they're not going to charge you the same as what new tube will cost. and these places prefer when you pay in cash. So if you get lucky, you might be able to score a piece for $150, maybe less.
If you need structural support in the form of tubes wouldn't bamboo be the more reasonable solution? It has greater tolerances and is lighter than pvc.
Yeah, good luck finding bamboo in 12 inch diameter.
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