The temperature for the can explode : 627 °C
Gay Lussac's Law
When the volume is not changed, the gas pressure is proportional to its absolute temperature
[tex]\tt \dfrac{P_1}{T_1}=\dfrac{P_2}{T_2}[/tex]
T₁=27 C+273=300 K
P₁=30 psi
P₂=90 psi
[tex]\tt T_2=\dfrac{P_2\times T_1}{P_1}\\\\T_2=\dfrac{90\times 300}{30}\\\\T_2=900~K=627^oC[/tex]