View all text of Subpart 38.15 [§ 38.15-1 - § 38.15-20]

§ 38.15-1 - Filling of tanks - TB/ALL.

(a) Refrigerated and semirefrigerated tanks shall be filled so that there is an outage of at least 2 percent of the volume of the tank at the temperature corresponding to the vapor pressure of the cargo at the safety relief valve setting. A reduction in the required outage may be permitted by the Commandant when warranted by special design considerations. Normally then, the maximum volume to which a tank may be loaded is:

VL = 0.98dr V/dL where: VL = maximum volume to which tank may be loaded. V = volume of tank. dr = density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. dL = density of cargo at the loading temperature and pressure.

(b) Nonrefrigerated tanks shall be filled so that their filling densities shall not exceed the ratios indicated in table 38.15-1(b).

(c) The “filling density” is defined as the percent ratio of the weight of the gas in a tank to the weight of water the tank will hold at 60 °F.

Table 38.15-1(b) - Maximum Permissible Filling Densities for Tanks Operating At or Near Ambient Temperature

Specific
gravity
at 60 °F.
Maximum permitted filling density
Unlagged tanks - water capacity Lagged tanks - all capacities
1,200 gal. and under Over 1,200 gal.
0.473-0.480384142
0.481-0.488394243
0.489-0.495404344
0.496-0.503414445
0.504-0.510424546
0.511-0.519434647
0.520-0.527444748
0.528-0.536454849
0.537-0.544464950
0.545-0.552475051
0.553-0.560485152
0.561-0.568495253
0.569-0.576505354
0.577-0.584515455
0.585-0.592525556
0.593-0.600535657
0.601-0.608545758
0.609-0.617555859
0.618-0.626565960
0.627-0.634576061

Note: Increase in filling densities to provide for seasonal changes may be considered by the Commandant upon presentation of factual evidence that safe operation can be effected.