Hot water flows in a $1-$m$-$long section of a pipe that is made of acrylonitrile butadiene styrene $($ABS$)$ thermoplastic. The ABS pipe section has an inner diameter of $D_1=22mm$ and an outer diameter of $D_2=25mm.$ The thermal conductivity of the ABS pipe wall is $0\mathrm{.}1\frac{W}{m}*K.$ The outer pipe surface is exposed to convection heat transfer with air at $20C$ and $h=10\frac{W}{m^2}*K.$ The water flowing inside the pipe has a convection heat transfer coefficient of $50\frac{W}{m^2}*K.$ According to the ASME Code for Process Piping $($ASME B$31\mathrm{.}3-2014,$ Table B$-1),$ the maximum recommended temperature for ABS pipe is $80C.$ Determine the maximum temperature of the water flowing in the pipe, such that the ABS pipe is operating at the recommended temperature or lower. What is the temperature at the outer pipe surface when the water is at maximum temperature?

The maximum temperature of the water flowing in the pipe should be

$C.$

The temperature at the outer pipe surface is $C.$