A steel pipe of 100 mm bore and 10 mm wall thickness, carrying steam at 250°C, is insulated with 30 mm of a molded high-temperature diatomaceous earth covering. This covering is in turn insulated with...

A steel pipe of 100 mm bore and 10 mm wall thickness, carrying steam at 250°C, is insulated with 30 mm of a molded high-temperature diatomaceous earth covering. This covering is in turn insulated with 60 mm of asbestos felt. If the atmospheric temperature is 22°C, calculate the rate at which heat is lost by the steam per meter length of pipe. The heat transfer coefficients for the inside and outside surfaces are 520 and 28 W/m
²K, respectively, and the thermal conductivity of steel, diatomaceous earth, and asbestos felt are 54, 0.12, and 0.09 W/mK, respectively. Also, calculate the temperature of the outside surface.