**Total internal pressure:**

$P = p (\frac{1}{4} \pi D^2)$

**Resisting wall:**

$F = P$

$\sigma A = p (\frac{1}{4} \pi D^2)$

$\sigma (\pi Dt) = p (\frac{1}{4} \pi D^2)$

$\sigma = \dfrac{pD}{4t}$

$8000 = \dfrac{p(4 \times 12)}{4(\frac{5}{16})}$

$p = 208.33 \, \text{psi}$ *answer*

The thickness is 5/6 of an inch T_T

The solution was 5/16 of an inch T_T

The problem was updated from t = 5/6 to t = 5/16. Thank you.

Where are the numbers "12" and "16" came from?

To make it inch from ft , 4*12

and it was actually 5/16 , there was fault in

question, i think...