A cast-iron stream pipe of 0.11m OD. and 0.10m U,D, carries stream at 200°c. It is to be insulated with a 0.025m thickness of an insulating material of k(m) = 0.035 Wm^-1k^-1. The ambient temperature is 0°c and the outer and inner heat transfer coefficients are respectively, 75 and 225 Wm^-2k^-1. Show that the heat flux through the wall of the pipe is less when the insulation is placed on the inner surface than what it is placed on the outer surface. What thickness of insulation, when placed on the outer surface, gives the same heat flux through the wall as a 0.0025m thickness placed on the inner wall?