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: V L = 0.98 d r V/d L where: V L = maximum volume to which tank may be loaded. V = volume of tank. d r = density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L = 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.