10
votes
Why do we neglect the radial stress in case of a thin pressure vessel?
I've been doing large pressure vessel design for a while, and ultimately it comes down to what is negligible v. what is not. Especially in the realm of atmospheric storage vessels, scrubbers, or ...
- 5,343
6
votes
Accepted
Minimum thicknesses of an elliptical cylinder pressure vessel
NOTE ON OBROUND VESSELS
While not a direct answer to your question, it should be quickly noted that ASME BPVC Section VIII, Mandatory Appendix 13, Section 10 has a section to design obround vessels (...
- 5,343
6
votes
Accepted
Making a radial (only) seal inside a small tube
The idea that I was describing in the comments earlier is pretty similar to that described by Mart - I imagined the tube (red) flaring out underneath the O ring, and the opposing taper being either ...
- 7,662
5
votes
Thin walled pressure vessel
Both Axial stress, (parallel to the axis of cylindrical symmetry) and Hoop Stress (in the tangential direction) are "Normal Stresses".
They are "Normal", because, if you consider an infinitesimal ...
- 7,662
5
votes
Easily compute a good approximation of heat conductivity of cooled semi-vacuum (water vapor + air)
In the molecular flow region of pressure, the thermal conductivity of an ideal, monatomic gas is obtained by this equation.
$$
k = \frac{1}{\pi^{3/2} d^2}\sqrt{k_B^3T/m}
$$
where $d$ is the ...
- 2,878
5
votes
Accepted
Calculating maximum internal pressure from maximum rated external pressure?
Vacuum pressure on a vessel is quite different than positive pressure.
Under positive pressure, the shell of the vessel is essentially under a uniform membrane tension due to the shell wanting to ...
- 3,587
5
votes
Is it safe to use a 125PSI rated auxiliary air tank with a 150PSI air compressor?
Don't do it!!
Just buy a pressure regulator to put between the two tanks that will decrease the pressure to below 125. You can get these for \$17 at home depot (https://www.homedepot.com/p/Husky-1-4-...
- 2,646
4
votes
A question on mechanical failure
It won't. Solid objects don't break in hydrostatic compression. The pressure is pushing all parts of the rod together, so there's nowhere for them to go except stay together. You can imagine an object ...
- 426
4
votes
How to remove protective valve cap from CO2 cylinder?
Use two strap wrenches or an equivalent - one on the tank and one on the cap.
You won't crush the tank :)
If you need to make one, then a length of 4*2 and some old car seat belt bolted to one end ...
- 15.3k
4
votes
Making a radial (only) seal inside a small tube
You could have a barely undersized O-ring around the nozzle, then use a thread around the nozzle to press on the O-ring with a nut. This would require to machining a custom nozzle and nut:
The part ...
- 4,705
3
votes
Accepted
How to calculate external pressure resistance in spheres and cylinders?
The mathematically determined formula for a sphere with a thin wall under external pressure (which is very inaccurate - keep reading!) is simply:
$$ \frac{2Et^2}{r^2\sqrt{3(1-\nu^2)}} $$
Where $E$ ...
- 5,343
3
votes
How do you get a closed vessel to >90,000 psi internal pressure
Contact an engineering firm with experience designing and building such systems and vessels to code. Otherwise, you're just building a bomb.
- 2,135
3
votes
Accepted
Tubing for explosive gas or hydrogen transfer
I would say that it is true and for that case there will be many relevant codes / regulations that need to be respected. Make sure you read them all before designing / altering the system.
- 15.3k
3
votes
Accepted
Why divide the dimensions of a pressure vessel by 39.37 when calculating discharge capacity?
This is because of units.
Getting the right answer with your units and their approach
What the people have done in your question is converted everything to metres. The division of 39.93 is because ...
- 386
3
votes
Check valve with precise cracking pressure
Check Valves are available with adjustable cracking pressures, using a preload spring to control the poppet force, for example: http://www.my-ssp-usa.com/products/valves/check-valves/adjustable-cpa
...
- 7,662
3
votes
Accepted
Can I increase the range of a howitzer by using more propellant?
Here are the limitations to this approach.
First of all a howitzer is specifically designed for relatively short-range use, by using a very steep (in some cases, almost vertical) launch angle which ...
- 14.1k
3
votes
How does a pressure vessel fail when the interal pressure exceeds the yield stress of the material?
A rupturing pressure vessel consists of an interplay between rupture of the walls, that causes a reduction in pressure via venting, while rupture of the walls also weakens the ability of the structure ...
3
votes
How do I limit the pressure of a tank to a fixed PSI?
I understand your setup as follows (in flow direction):
compressor with cutout set to 150 PSI
tank (T1) rated for compressor, with safety valve
(planned) pressure regulator (PR)
additional tank (T2), ...
- 4,705
3
votes
How do I limit the pressure of a tank to a fixed PSI?
In industrial settings, the correct piece of equipment is referred to as either a Pressure Relief Valve (PRV) or Pressure Safety Valve (PSV). These are spring-loaded valves with a few specific ...
- 605
3
votes
Accepted
Why is the thin-walled cylinder more likely to experience failure along its axis than along its hoop/circumference?
Actually, the pressure inside the vessel is uniform and constant everywhere. What happens is that geometry results in reduced stresses in one direction and not in the other.
There may be some ...
- 24.2k
3
votes
Accepted
A query regarding constructing vacuum sealed vessels
Typically the maximum stress for a thin walled spherical pressure vessel for a given diameter, thickness and pressure is:
$$\sigma = \frac{P\cdot R}{2\cdot t}$$
where:
$\sigma$ is the observed ...
- 24.2k
2
votes
Accepted
Is this pressure vessel feasible?
Sure. CO2 cartridges are made of steel and hold 850 psi. You want to use brass, which has 80% of the yield strength of steel (200MPa vs 250MPa) to hold 35% of that pressure. Not to mention the fact ...
- 3,575
2
votes
Why divide the dimensions of a pressure vessel by 39.37 when calculating discharge capacity?
By dividing the diameter and length dimensions, which are in inches, by 39.37 you are converting them to metres. The problem you are trying to solve has inputs that are in both English and metric ...
- 9,582
2
votes
Measure stress of gas acting on a spherical container
Spherical vessels have a stress in the wall equal to,
$$ \sigma = \frac{p r}{2 t} $$
where $p$ is the internal gage pressure, $r$ is the inner radius of the sphere, and $t$ is the thickness of the ...
- 251
2
votes
Accepted
Will helium gas lift more weight in air when it is spread over large volume compared to equal weight heavily compressed small volume?
As a reality check lets consider industrial gas tanks as the specifications are easily available.
A BOC size D hydrogen tank has a gross weight of 57kg and contains 23kg of hydrogen at 230bar.
At ...
- 15.1k
2
votes
Accepted
Burst pressure of a sphere
For spheres,stresses in the material is same in all directions.So ,hoop stress and longitudinal stresses are the same.
Using similar abbreviations, as P for pressure(gauge) inside sphere ,FS for ...
- 36
2
votes
Accepted
Liquid vs. gas check valves
No, liquid check valves function on density, viscosity or velocity or a combination and the mass is taken into account - gas check valves are designed to deal with a fluid 700 or more times less dense ...
- 15.3k
2
votes
Can a water pressure switch be used as a low-water cutoff means for a steam boiler?
Hydrostatic pressure of water changes per depth according to Pascal's law which equates to $1 \text{Pa} = 1000 \text{kg}/\text{m}^3 * 9.81 \text{m}/\text{s}^2 * h$ or $101 \text{Pa} /\text{m}$ or $1....
- 5,751
2
votes
How to calculate the pressure loading of a vented silo explosion?
The pressure in the silo is determined by the temperature rise, caused by the combustion. The end temperature after combustion can be calculated like this:
$$T_{end}= \dfrac{E}{(m_{air}+m_{fuel})C_V}+...
- 1,174
2
votes
Wall temperature of pressure cylinder - Boundary condition
There are a lot of variables to consider for a thermal analysis, but none of them require pressure as a boundary condition. As alephzero indicated in their comment, this is function of heat source ...
- 51
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