Steam flows through a pipe at an average temperature T = 200 C, the inner and outer radii of the pipe are r1= 8 cm and r2= 8.5 cm, and the outer surface of the pipe is heavily insulated. If the convection heat transfer coefficient on the inner surface of the pipe is h= 65 W/m^2*K, write the governing DE and express the Boundary Conditions on the inner and outer surfaces of the pipe during transient periods.