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6 votes
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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 (...
Mark's user avatar
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6 votes
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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 ...
Jonathan R Swift's user avatar
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 ...
Jeffrey J Weimer's user avatar
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-...
Daniel K's user avatar
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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 ...
user1318499's user avatar
4 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 ...
Jonathan R Swift's user avatar
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 ...
Solar Mike's user avatar
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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 ...
mart's user avatar
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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 ...
Jonathan R Swift's user avatar
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.
DLS3141's user avatar
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3 votes
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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 $E$ ...
Mark's user avatar
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3 votes
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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.
Solar Mike's user avatar
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3 votes
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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 ...
niels nielsen's user avatar
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 ...
MeEngineerTrustMe's user avatar
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), ...
mart's user avatar
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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 ...
ChemE mang's user avatar
3 votes
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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 ...
NMech's user avatar
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3 votes
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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 ...
NMech's user avatar
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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 ...
TRF's user avatar
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2 votes
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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 ...
Chris Johns's user avatar
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2 votes
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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 ...
Solar Mike's user avatar
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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}+...
Bart's user avatar
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2 votes
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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 ...
Mohit saini's user avatar
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....
ratchet freak's user avatar
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 ...
mechengjoe's user avatar
2 votes

How to determine minimal wall thickness for a rectangular pressure vessel?

The reason that you can't find anything on Google is that it is a bad idea to make a rectangular pressure vessel. You get stress concentrations at the corners which makes the vessel much weaker. This ...
Daniel K's user avatar
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2 votes

Regulating pressure down inside vessel as it increases

The only way to keep pressure constant as volume is reduced is by let out the same amount of liquid/gas as the volume contracts. That is exactly what a pressure reducing valve does. As long as it ...
Tiger Guy's user avatar
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2 votes
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Regulating pressure down inside vessel as it increases

Have a second separate balloon that expands as the first is compressed. This will also keep the pressure constant as the volume is increased if that is part of your requirement.
Solar Mike's user avatar
  • 15.8k
2 votes

Is it safe to use a 125PSI rated auxiliary air tank with a 150PSI air compressor?

A 10 or 25 psig overpressure of a tank is well into a potential failure for the tank. The 140 psig safety valve is used because that accounts for the true pressure capability of the tank plus the ...
J. Ari's user avatar
  • 478
2 votes
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How does a pressure vessel fail when the interal pressure exceeds the yield stress of the material?

As jko points out in a comment, the hoops tress is always higher than the medium pressure, so the case as presumed in the question cannot happen and we don't see "ineresting" new failure ...
mart's user avatar
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