Spherical Hoop Stress Thick-walled Section (Internal & External Pressure)

Spherical Hoop Stress Thick-walled Section (Internal & External Pressure) Formula
$\sigma_h \;=\; \dfrac{ (p_i \cdot r_i^2) - (p_e \cdot r_e^2) - (r_i^2 \cdot r_e^2) \cdot \left( p_e - \dfrac{ p_i }{ r^2 } \right) }{ r_e^2 - r_i^2 }$
Symbol	English	Metric
$\sigma_h$ (Greek symbol sigma) = Spherical Hoop Stress	$lbf\;/\;in^2$	$Pa$
$p_i$ = Internal Pressure	$lbf\;/\;in^2$	$Pa$
$r_i$ = Internal Radius	$in$	$mm$
$p_e$ = External Pressure	$lbf\;/\;in^2$	$Pa$
$r_e$ = External Radius	$in$	$mm$
$r$ = Radius to Point of Intrest	$in$	$mm$