The most appropriate average temperature loss is through its 5.25 cm steel tube, 3.91 mm thick, and the tube covered with a 102 mm thick layer of insulation. General I learned that the conductivity of the pipe material is 3.75 watt meter Kelvin. The insulating material is 0.00288 watts/meter. Kelvin. The inner wall temperature is 120C and the outer surface temperature is 20C. Then calculate the common surface temperature between the steel and the insulator.