UFC 3-460-03
21 JANUARY 2003
11.12.5.3. The methods and facilities available for floating and removing fuel sludge and hosing
down the tank are not adequate.
11.12.6. In the case of special fuels, ensure combustible gas vapor indicators will detect vapors of the
special fuel.
11.13. Initial Tank Cleaning from Outside the Tank.
11.13.1. After completing the pre-entry procedures, begin the initial inspection or cleaning from
outside the tank. Continue ventilating during initial operations, where possible, to ensure the removal
of vapors from the tank. Test frequently for explosive vapors. Stop cleaning operations if the vapor
concentration rises above 20% of the LEL.
11.13.2. Direct water streams through open man-ways to dislodge scale, sludge, and fuel residue, and
float it to a water draw-off or pump-out connection. Disposal costs are high, so use water sparingly.
Pressure washers are a means to speed cleaning while conserving water. If used, ensure pressure
washer nozzle is electrically bonded to the tank.
11.13.3. Place the fuel-water-sludge mixture in drums or a portable tank, and dispose of sludge in
compliance with state and local environmental laws. Contact the BCE environmental coordinator for
the proper disposal method.
11.13.4. Stop hosing down the tank when the vapor level is 20% LEL or higher.
11.13.5. Use air-driven, double-diaphragm-type pumps for removing sludge and excess water.
11.14. Tank Entry.
11.14.1. After initially cleaning the tank from the outside, continue ventilation and vapor readings at
the manhole or equipment to determine when entry can be made. Once the vapor indicator registers
10% LEL or less, entry is authorized. Since vapors will be present as long as fuel, scale, or sludge
remains inside the tank, continue forced ventilation until all such material has been removed.
11.14.2. All entrants must be equipped with approved PPE.
11.14.3. Maintain an uninterrupted air supply until all persons are out of the tank and have removed
their facepieces. Anyone wearing PPE detecting an odor (such as fuel) must leave the tank
immediately and not re-enter until the cause has been determined and equipment repaired or replaced.
11.14.4. Repeat tests for explosive vapors at fifteen-minute intervals while workers are in the tank.
Stirring sludge releases vapors and increases the vapor concentration. Remove puddles of fuel-water-
sludge to keep vapor readings below 20% LEL.
11.14.5. After removing sludge from the tank and with personnel wearing PPE, scrape the bottom of
the tank and 0.9 meter (3 feet) up the sides until all loosely adhering rust and scale have been
removed from the tank. Wash down the remainder of the tank with high-pressure hoses. Include the
metal supports, braces, the upper portion of horizontal tanks, and the decks (tops) of vertical tanks.
Wash these areas until the water pumped out of the tank is clean.
11.14.6. Water discharged from the tank must be contained and disposed of as instructed in
paragraph 11.13.3.
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