superheated steam at 575'c is routed from a boiler to the turbine of an electric power plant through steel tubes (k ! 35 w/m!k) of 300-mm inner diameter and 30-mm wall thickness. to reduce heat loss to the surroundings and to maintain a safe-to-touch outer surface temperature, a layer of calcium silicate insulation (k ! 0.10 w/m!k) is applied to the tubes, while degradation of the insulation is reduced by wrapping it in a thin sheet of aluminum having an emissivity of ) ! 0.20. the air and wall temperatures of the power plant are 27'c