Stress in thin sphere

## Calculate the maximum allowable pressure difference allowed between the inside and outside of a sphere 50 mm mean diameter with a wall 0.6 mm thick if the maximum allowable stress is 1.5 MPa.

Solution:

Given,

            Diameter, D = 50 mm = 0.05 m

            Thickness, t = 0.6 mm = 0.0006 m

            Maximum stress, σ = 1.5 MPa = 1.5x10⁶ Pa

            Pressure difference, P =?

We know that,

Stress in thin sphere,

                                  σ = P.D/4t

                            => P = 4t σ/D

                            => P = 2 x 0.0006 x 15x10⁶ /0.05

                            => P = 72 KPa

So, Maximum allowable pressure difference = 72 KPa