$(2)$ A steel pipe carrying steem has an outside radus of dihsm. Thare is an insulation on the pipe with theckness of $0,076m$ of insulation having themal conductivity $k=0,063\frac{}{m}.K.$ Temperature betwean pipe wall and the insulation is reasured as $11sC$ and the other at the outer sirface of the outer surtace of the insolution

a$)$ Calculate the rate of heat lose $($a$)$ if the langth of the pipe $1m.($use resisiance$)$

b$)$ Calculate overall heat tronsfer coefficient bosed on the outside orea of the insowtion $(A_2)$ if ambiont $O_2($oir$)$ temperature is $25C$ ind temperature of steom inside the pipe is $120C$

a$)$ Calculate critical thackress for insolution if $h=20\frac{w}{m^2},k.$