DieselShip's Online Content Library

Q6. A steel pipe 100 mm bore and 10 mm wall thickness carries dry saturated steam at 12 bar. It is covered with a 50 mm layer of moulded insulation which in turn, is covered with a 60 mm layer of felt. This combination gives an outer surface temperature of 30ºC. The felt is to be replaced with a new insulation which will maintain the original heat transfer rate but requires an interface temperature of 82.5ºC between the felt and the insulation. Calculate EACH of the following:

(a) The original rate of heat loss per unit length of pipe

(b) The change in the moulded insulation thickness to maintain the required condition.

Note: Inner surface heat transfer coefficient = 550 W/m²K

Thermal conductivity of moulded insulation = 0.07 W/mK

Thermal conductivity of felt = 0.09 W/mK