How do I calculate a cylinder barrel wall thinkness, relative to the working pressure?

use Hoop stress formula,

t,thickness =
Pressure x Bore Diameter x FOS / 2x Yield stress

FOS = factor of safety (~3)
Pressure = working pressure

FOS = critical force on shaft / maximum possible load on shaft

You should also check radial displacement to insure that the maximum operating pressure does not render the piston seals ineffective as the result of an excessive extrusion gap.

Where
P = pressure
E = modulus of elasticity
u = Poisson's ratio
r1 = internal radius
r2 = external radius

Assuming steel then E = 3 * 10^7 and Poisson's ratio is 0.3.

delta r1 = P * r1/E * ((r2^2 + r1^2)/(r2^2 - r1^2) * u)

This should be less than the allowed extrusion gap for the piston seals you intend to use.

Hi Damo '
Please review the attached PDF file.
Nahum

WallTick.pdf (81 Kb, 155 downloads)

Google BARLOW'S FORMULA and go to the Texas Pipe site - They have a calculator...

quote:

Originally posted by Lewey S.:
Google BARLOW'S FORMULA and go to the Texas Pipe site - They have a calculator...

You will still need to check that the cylinder wall radial displacement at operating pressure is not great enough to cause damage to the piston seals....