# Would a 4'x8'x1' piece of glass be able to contain 60psi?

1. Mar 28, 2015

### Physt

Preface: This isn't an actual project, just trying to get the design to be realistic for a 3D model in a video game.

I know most pressure vessels are round and the overall shape of this one would be round, but it's very large (about half a football field large) so it would be composed of a bunch of panels. The 4'x8'x1' piece of glass would be supported evenly on all four 1'-wide sides by being clamped into a support 1.5 inches deep (so the actual surface area would be 45"x93").

Would this be good enough to hold 60psi (actually 1atm, but from what I've read about double the pressure is a good design parameter to go by)?

What would be the maximum pressure of this design?

Does anyone happen to have the equations for a calculating the maximum pressure allowable for flat panels like this so I might plug different materials into the equations?

2. Mar 28, 2015

### Staff: Mentor

~30cm thick? That is a massive block of glass. The biggest window at the ISS has a diameter of 80cm and is just 2.5 cm thick (there are two glass panes behind each other so one serves as backup) - and I'm sure they have a huge safety margin built in.

3. Mar 28, 2015

### Physt

From all I've fathered thus far the thickness of the glass grows quite a bit relative to the length of the shortest dimension. ~30cm is my best guess thus far based on the calculators available online for curved surfaces at approximately 122cm across with a little more for the sake of it being a flat surface.

The best calculator I've found online thus far for glass panels is http://www.dullesglassandmirror.com/glass-shelf-weight-load-calculator.aspx and a 45"x93" piece of tempered glass with a thickness of 1" and supports at 48" (closest I could get to supported along all four edges with that calculator) it comes in at 9416.25 lbs max, so divided by (45*93) yeilds 2.25psi, 27psi for 12" of thickness. So if that estimate is close it wouldn't quite be thick enough (without even doubling the psi for the sake of safety).

Guessing (hoping) that's not an entirely accurate estimate though.

4. Mar 28, 2015

### Staff: Mentor

The allowed pressure does not scale linearly with thickness. The square is a better estimate, so 12 times the thickness gives 144 times the pressure - a good safety factor with your values.

I really don't like weird and exotic unit systems.

5. Mar 28, 2015

### Physt

Thanks, I too dislike the English system, but if one were to buy a large sheet of glass in the US it would likely be a 4'x8' pane - same goes for layered glass/polycarbonate stacks - so figured I'd try to work around that.