//(Cylinders and Pressure Vessels) Example 22.7
//(Input data of 22.6)
//Inner diameter of the steel tube D1 (mm)
D1 = 20
//Outer diameter of the steel tube D2 (mm)
D2 = 40
//Outer diameter of the jacket steel tube D3 (mm)
D3 = 60
//Limiting maximum principal stress induced in any tube sigmaMax (N/mm2)
sigmaMax = 100
//Young's modulus of the steel tube E (N/mm2)
E = 207000
//Internal pressure acting on the cylinder Pi (MPa)
Pi = 300