pressure vessel stress calculations
TRANSCRIPT
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Stress calculations for a 5 foot Long 2 foot in
diameter cylindrical pressure vessel during
normal operation pressure of 150 psi
Hoop Stress or Stress in the Circumferential
Direction = Pr/t
With P = 150 psi, r = 12 in, and t = .25 in
Hoop Stress = 7200 psi
Axial Stress = Pr/2t
With P = 150 psi, r = 12 in, and t = .25 in
Axial Stress = 3600 psi
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Max pressure calculations for a 5 foot Long
2 foot in diameter cylindrical pressure
vessel
Calculations based on Grade B pipe with aMinimum Yield Strength: 35000 psit = .25 in
r = 12 in
Max Pressure based on Hoop Stress = 35000 psiPressure = 729.17 psi
Max Pressure based on Axial Stress = 35000 psiPressure = 1458.3 psi
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Stress calculations for 12 in diameter
spherical end caps during normal operation
pressure of 150 psi.
Hoop Stress = Axial Stress = Pr/2t With P = 150 psi, r = 6 in, and t = .25 in
Hoop Stress = 1800 psi
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Max pressure calculations for 12 in
diameter end caps
Calculations based on Grade b pipe with a
Minimum Yield Strength: 35000 psi
t = .25 in
r = 6 in
Max Pressure based on Hoop Stress = 35000 psi
Max Pressure = 2916.7 psi
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Results
Based on the previous calculations we have
determined that the limiting factor in regard
to max pressure within the pressure vessel is
the Hoop Stress for the cylindrical pressurechamber. But it is still 3.86 times the intended
operation pressure of 150 psi.
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Heating System Selection
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Convection Incoloy Tubular Heating selected Is most common in commercial autoclaves
Easily obtained used in home appliances
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Insulation of Vessel
Prevent heat from escaping (minimize power required toheat)
Keep surface temperature low to prevent burning danger
Can also add outer covering, i.e. sheet metal (extra cost)
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Insulation Thickness
0.4 m O.D. corresponds to a 3.5 insulation layer
Common (R13)
No real gains if any thicker
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Heating of Vessel
Surface temp. at 3.5 thickness is 80F
Heat loss also levels off at 3.5
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Total power to maintain max. temp: ~470W
Total power to heat up air at 15F/min (total 27min): ~1.5kW
Allowing for thermal mass of
parts/molds/pipe, ~4-5 kW needed Can easily be run on 240V power
Elements can be obtained to provide this
Blowers inside vessel will help maintain
uniform temp.
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Estimated Heating System Costs
63 ft^2 R13 fiberglass ($20)
4-5kW incoloy tubular heating element ($250)
Potential sheet metal covering ($125) Shipping, fittings, etc ($125 est.)
Subsystem estimated total: $400-$500