Q$\mathrm{.}1)$ Find the thickness of metal necessary for a steel cylindrical shell of internal diameter $150mm$ to withstand an internal pressure of $50\frac{N}{m}{m}^2,$ and no pressure at outer surface of the cylinder. The hope stress at internal surface is not exceed $150\frac{N}{m}{m}^2.$ Solve using hoop stress$=$A$+$B$/$r$^2$

And radial stress$=$ A$-$B$/$r$^2$

NOT hoop stress $=$Pd$/2$t