46 C.F.R. § 154.451
Design vapor pressure.
Cite as 46 C.F.R. § 154.451 (2026)
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
/
Δ
σ
A
)
2
;
σ
m
= design primary membrane stress;
Δ
σ
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.