Steam at $250$C flows in a stainless steel pipe $($k $=15$ W$$m$-1$K$-1)$ whose inner and outer diameters are $4$ cm and $4\mathrm{.}6$ cm$,$ respectively. The pipe is covered with $3\mathrm{.}5$ cm thick glass wool insulation $($k $=0\mathrm{.}038$ W$$m$-1$K$-1).$ Heat is lost to the surrounding air and surfaces at $3$C by convection and radiation. Taking the heat transfer coefficient inside the pipe to be $80$ W m$-2$K$-1,$ determine the rate of heat loss from the steam per unit length of the pipe when air is flowing across the pipe at $4$ m$$s$-1.$ For radiative heat loss from the surface of the pipe, assume hrad $=1\mathrm{.}5$ W m$-2$K$-1.$ Evaluate the air properties at a film temperature of $5$C and $1$ atm. Reflection: which heat transfer resistances can be ignored?