A horizontal pipe carrying saturated steam at $14\mathrm{.}71$ bar has $0\mathrm{.}078$ m inner diameter and $0\mathrm{.}089$ m outer diameter. It is insulated with $0\mathrm{.}02$ m of insulation $($k$=0\mathrm{.}05$W$/$mC$).$ The ambient air temperature is $25$ C$.$ What is the heat loss per unit length?