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

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§ 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 = 0.98drV/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.
0.473-0.480 38 41 42
0.481-0.488 39 42 43
0.489-0.495 40 43 44
0.496-0.503 41 44 45
0.504-0.510 42 45 46
0.511-0.519 43 46 47
0.520-0.527 44 47 48
0.528-0.536 45 48 49
0.537-0.544 46 49 50
0.545-0.552 47 50 51
0.553-0.560 48 51 52
0.561-0.568 49 52 53
0.569-0.576 50 53 54
0.577-0.584 51 54 55
0.585-0.592 52 55 56
0.593-0.600 53 56 57
0.601-0.608 54 57 58
0.609-0.617 55 58 59
0.618-0.626 56 59 60
0.627-0.634 57 60 61

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.

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