• Design a helical spring for a spring loaded safety valve for the following conditions :  Operating pressure = 1 N/mm2  Maximum pressure when the valve blows off freely = 1.075 N/mm2  Maximum lift of the valve when the pressure is 1.075 N/mm2 = 6 mm  Diameter of valve seat = 100 mm  Maximum shear stress = 400 MPa  Modulus of rigidity = 86 kN/mm2  Spring index = 5.5