Code of Federal Regulations Title 46. Shipping § 46.154.451 Design vapor pressure

The P_o (kPa) of an independent tank type C must be calculated by the following formula:

where:

A = 1.813 (σ_m/ ^▵ σ _A)²;

σ_m = design primary membrane stress;

^▵ σ _A = (allowable dynamic membrane stress for double amplitude at probability level Q=10^-8) 53.9 MPa (7821 psi) for ferric and martensitic steels and 24.5 MPa (3555 psi) for 5083–0 aluminum;

C = characteristic tank dimension that is the greatest of h, 0.75b, or 0.45 l;

h=the height of the tank or the dimension in the vessel's vertical direction, in meters;

b=the width of the tank or the dimension in the vessel's transverse direction;  in meters;  and

l=the length of the tank or the dimension in the vessel's longitudinal direction, in meters;  and

ρ=the specific gravity of the cargo.