A steel pipe 100 mm O.D. and 5mm thick carrying superheated steam at 3000C is to be insulated such that the heat lost from each meter length of the pipe is restricted to 100 kcal / m hr. The temperature of the surroundings is 300C. The inside and outside heat transfer coefficients are 500 kcal/m2/hr and 10 kcal/m2/hr0C. The thermal conductivity of steel may be assumed to be 40 kcal/m/hr0C. Determine the insulation thickness and the temperature at its outer and inner radii. The thermal conductivity of insulation may be assumed to be 0.045 kcal/m hr0C.