A manhole cover is provided in the top of each tank to gain access for cleaning and maintenance. A Buns-N-Cork gasket is installed between the tank and manhole cover plate to prevent leakage. The outer tank manhole cover plate is fitted with a steam-out connection. Outer Tank The seawater supply riser enters the outer tank at the top and terminates in a diffuser near the bottom. The seawater required for pressurizing the tanks is discharged through this line. A pressure gage line extends from the top of the outer tank to a pressure gage located in the pump room. The gage has a red pointer, indicating the maxi- mum allowable tanktop pressure for that set of tanks. (Allowable pressures will vary for the different classes of ships.) A warning plate attached near each gage reads, “THE MAXIMUM ALLOWABLE TANK-TOP PRESSURE INDICATED BY THE FIXED RED POINTER SHALL NOT BE EX- CEEDED WHEN THE SHIP IS FUELED.” Two in-tank reservoirs for water-filled, static- head gasoline gages are installed in the outer tank. One reservoir is installed at the top of the tank and the other at the bottom directly underneath the upper reservoir. Stuffing boxes are provided where the tub- ing for the gage passes up through the outer tank. The stuffing boxes prevent leakage of gasoline and seawa- ter out of the tank. They also prevent nitrogen in the cofferdam from entering the tanks. NOTE LPDs have water filled, static-head gages but are scheduled to have them replaced with TLIs. LHAs already have TLIs. The outer tank is interconnected with the drawoff tank by a sluice pipe. The sluice pipe extends from near the top of the outer tank and terminates in a diffuser at the bottom of the drawoff tank. The top of the sluice pipe is flared to reduce friction. The outer tank completely envelopes the drawoff tank. The outer tank has a motor-driven stripping sys- tem installed for deballasting the tank. The inde- pendent hand-stripping system also ties into the outer tank to remove water and sludge from the bottom of the tank. Draw-off Tank The draw-off tank is the smaller of the two tanks. It is the tank from which gasoline is drawn when servicing or off-loading fuel. It is the first tank filled when MOGAS is being received and the last tank emptied when MOGAS is being off-loaded. The gasoline supply riser extends from the extreme top of the drawoff tank to the common suction header of the gasoline pump. The recirculating header termi- nates in a diffuser at midpoint in the draw-off tank. The draw-off tank is provided with an independent stripping system to remove water and sludge from the bottom of the tank. This system is the same hand-oper- ated type used with the JP-5 service tanks. The suction line is fitted with a shutoff valve and extends from three-fourths of an inch off the bottom of the lowest part of the tank. The discharge line, fitted with a sight glass, test connection, one-way check valve, and a shutoff valve, terminates in two places: 24 inches off the bottom of the outer tank, and overboard. The draw-off tank also has a water-filled, static- head gage, or a TLI. Drain Tank The drain tank is a small tank located inside the outer storage tank. The drain tank stores contaminated MOGAS/water that is filtered/separated out of the MOGAS. Cofferdam The cofferdam provides two-fold protection for the storage tanks. The cofferdam is normally kept charged with nitrogen (Nz) to 3 psi at 50% inertness or carbon dioxide (COZ) at 35% inertness to reduce fire and ex- plosion hazards. It also collects any leakage from the storage tanks. The nitrogen supply line for purging and charging the cofferdam terminates in a loop, which completely encircles the outer tank. From this loop (located near the top of the cofferdam), pipes (legs) extend down to near the bottom. Each leg is fitted with a diffuser, which serves to spread the inert gas throughout the space. A stop valve for controlling the nitrogen entering the tank is located in the main supply line at the pump room level. An air escape riser, fitted with a shutoff valve, extends from the top of the cofferdam and vents to atmosphere at the 02 level. A bypass line is installed around the shutoff valve. This line contains a 6-7