$5.$ A thin$-$walled tube with closed ends has an inner diameter of $180$mm and a wall thickness of $2\mathrm{.}5$ mm$,$ and it is loaded with an internal pressure of $10\mathrm{.}0$ Mpa.

The material is the Cr$-$Mo$-$V steel of Table $16\mathrm{.}3$ below, and the temperature is $500$C$.$

Estimate the life to creep rupture.