# Square or Rectangle 30 psi storage tank

notinthebox
If I want to make a Square or Rectangle storage tank 5 feet deep and 22 feet long and 1 foot wide. The tank will be under 30 psi and also vacuum. That’s not hard to do what I want is the walls not to deflect more then .001 of an inch. The walls can be plastic, plywood with a steel sheet or steel. I want the walls to be flat and smooth. Thanks for any help

tygerdawg
Ummmm...I'm no stress analysis expert, but it seems you want to design a pressure vessel. 30 psi on such a long span of 22 feet and you want deflection to be max of 0.001 inch? Let's see...30 lbf/in^2 X (5 ft X 12 in) X (22 ft X 12 in) = a whole heck of a lot of force. You'll either have to internally/externally reinforce this thing or make the walls as thick as a battleship hull plate. And a cubic-shaped vessel...well, there's all kinds of problems with that concept. Butane tanks, etc., are cylindrical or spherical for a reason.

Either way, this should be governed by pressure vessel design practices (for example, ASME Pressure Vessel Codes), else you will construct a bomb. Tread lightly there, sport, there be nasty beasties about.

notinthebox
Its for water what would the max lenth I should go with then?

RocketSci5KN
This sounds more like a homework problem... If this is a real design, you really must use a cylinder... any other shape proves you have no clue and should not construct such a thing.

Homework Helper
If I want to make a Square or Rectangle storage tank 5 feet deep and 22 feet long and 1 foot wide. The tank will be under 30 psi and also vacuum. That’s not hard to do what I want is the walls not to deflect more then .001 of an inch. The walls can be plastic, plywood with a steel sheet or steel. I want the walls to be flat and smooth. Thanks for any help

Start with the basic fact that a pressure of 1 atmosphere is about 1 ton per square foot. So 30 psi is about 2 tons per square foot. That's more that 200 tons pushing out the 5 ft x 22 ft side of your rectangular tank.

That's why you don't find many rectangular pressure tanks - and certainly not many made out of plywood or plastic.

Homework Helper
Its for water what would the max lenth I should go with then?

I don't see the connection between "a 5 ft depth of water" and "30 psi and also a vacuum".
Even a 22 ft depth of water is only about 10 psi at the bottom (and zero at the top).

notinthebox
It a piston for a pump