Steam at $100\backslash$deg C is flowing inside a steel pipe $($OD$=3\mathrm{.}5$ in$,$ k$=50$ W$/$m$\backslash$deg C$,$ wall thickness$=0\mathrm{.}216$ in$)$ located horizontally in a large tank which is completely filled by water at $26\mathrm{.}7\backslash$deg C$.$ Calculate the free convection heat transfer rate to water per unit length of the pipe.