§ 154.451 - Design vapor pressure.

§ 154.451 Design vapor pressure.

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

P_o = 196 + AC(_ρ) 3⁄2

where:

A = 1.813 (σ_m/^Δσ_A)²;

σ_m = design primary membrane stress;

^Δσ_A = (allowable dynamic membrane stress for double amplitude at probability level Q = 10⁻⁸) 53.9 MPa (7821 psi) for ferritic and martensitic steels and 24.5 MPa (3555 psi) for 5083-0 aluminum;

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

where:

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.