Strenghtening Water Tank

[imagineers]

I am designing a water tank 13"x 6" x 6", and it should be able to handle around 250psi, I am not sure how to structurally make it stronger inside. As you can see in the pic I have three outlets and one inlet, also in the pic you can see drawn in red an idea on a couple ribs to be welded into place for strength, not sure if this is the way to do it or not. Any help would be appreciated.

 

[MintJulep]

No, it's not. If for no other reason than as-drawn it wouldn't be possible to manufacture.

At any rate, this is not a "tank", it's a pressure vessel. There are probably codes, standards and laws governing the design requirements.

 

[imagineers]

well it actually is a reservoir for coolant, and operating pressure is only around 10psi, but most of the components are rated for around 220 psi, so I wanted to try and strengthen it to handle this, even though it may never see that pressure. It's made of stainless. I know this can be made, as we have made it I just wanted to strengthen it

 

[racookpe1978]

No. Design it for the expected pressure in use, plus a reasonable safe margin. (Or as required by Code for a PV.)

If operational pressure is 10 psig, design it for that.

 

[MikeHalloran]

You want it 'strong', machine it from solid billet.
Expect complaints about weight and cost and manufacturing difficulty.

Have there been any actual failures, or failures to meet expectations, or are you just worrying?

The problem with just adding baffles, ribs, whatever, based on speculation, fear, or eyeball engineering, is that there are a lot of ways to make the overall product weaker by adding material.

Are those sanitary flanges? The shanks appear fairly thick. I might expect fatigue cracks in the walls near the flange attachment welds. ... if the unit is subject to vibration, facts not in evidence. If that is the case, the unit might become more satisfactory by reducing the thickness of the flanges near the tank welds. It's also possible to make the joints stronger by making the sheet thicker, near the tank-flange welds, but that's easier said then done.

Do the flanges always connect by hose to everything else? If any rigid-ish pipework attaches, you might want to apply moments in your analysis, representing misalignment and deflection of other stuff.

You don't necessarily need Finite Element Analysis to figure out what do next, but you do need some kind of Analysis, starting with estimates of the real loads applied in all possible circumstances, and decisions about how you expect the product to behave in each load case. Example, at 250psi internal pressure (please use water or grease, no gas, in any testing you might try), I'd expect the tank walls to balloon out and change the geometry to look a bit more like a basketball or a cow's udder. Is that a bad thing? Would such extreme deflection cause the product to stop working properly? You need to ask and answer a fair number of questions like that make progress.




Mike Halloran
Pembroke Pines, FL, USA

 

[desertfox]

Hi

If the top plate was a separate piece and bolted on, the ribs in your sketch could be welded in as shown but the lid would be separate item.
Is the tank full of fluid or is it only partially filled?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[imagineers]

the tank is probably about 3/4 full of glycol water mix. I simulated this in solidworks, adding 30psi as my working pressure and the tank appeared to break apart, I added some ribbing as seen in the pic and it appeared to withstand the pressure. but flow will be more turbulent

 

[BUGGAR]

"You want it 'strong', machine it from solid billet."

Are your "vessel" dimensions in inches or feet? I assumed they were in feet and the welders could easily crawl in and out of your nozzles to weld inside, right?

 

[imagineers]

BUGGAR,

welds will be fillet welds around the outside diameter of the tri clamps

 

[imagineers]

Also I will have a pressure relief at 20PSI, but operating pressure will be somewhere around 5PSI, and is on the suction side of the pumps

 

[MintJulep]

It looks like the outside of your tank is two bent pieces - top and sides, front, bottom, back. Right?

So, please write out an exact assembly sequence for your design, stating when each piece gets put in, and when each weld is made.