Where:
d = inside diameter in inches;
E = 1.0 welded joint efficiency;
P = minimum required bursting pressure in psig;
S = minimum tensile strength of plate material in p.s.i. as prescribed in §179.300-7;
t = minimum thickness of plate material in inches after forming.
s
=[ p (1.3 D2 + 0.4 d2 ] / ( D2-d2 )
where:
d = inside diameter in inches;
D = outside diameter in inches;
p = tank test pressure in psig;
s = wall stress in psig
49 C.F.R. §179.300-6