A gas at 289 K surrounds a long metal tube with outer radius r1=17 mm and outer surface temperature of 400 K. It is desired to decrease heat transfer by covering the tube with two layers of insulation, both layers 1.9 cm thick. Insulator A has a conductivity k= 0.054 W/m*K, while the conductivity of insulator B is k= 0.127 W/m*K.

In what order should the insulators be placed so that heat transfer is as low as possible? Once the order of the insulators has been found, calculate the net transfer for 3 m of insulated pipe.