A 4-in.-OD pipe is to be used to transport liquid metals and will have an outside surface...

A 4-in.-OD pipe is to be used to transport liquid metals and will have an outside surface temperature of 1400°F under operating conditions. Insulation is 6 in. thick and has a thermal conductivity expressed as

where k is in Btu/h ft °F and T is in °F, is applied to the outside surface of the pipe.

a. What thickness of insulation would be required for the outside insulation temperature to be no higher than 300°F?

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b. What heat-flow rate will occur under these conditions?