Prepare and Clean for Purging of Fuel Tanks

purging. Under no circumstances will repair on fuel tank

mediately in order to retard the process of interior

begin until declared safe by safety personnel.

oxidation.

d. Only competent personnel thoroughly instructed

7. Alternate Procedure for Purging. a. Drain fuel

in the proper handling and reading of the vapor indicating

and remove fuel tank from vehicle. Exercise normal

instruments (explosion meter) will perform vapor tests.

precautions in handling since tank will still contain

e. Personnel engaged in purging operations will:

explosive vapors.

(1) Not wear wool, nylon, silk, rayon or other

b. Remove all fittings and fuel inlet cap. Retain for

clothing having a tendency to generate static electricity.

reinstallation.

(2) Wear clean cotton clothing with no metal

c. Use alkali steam cleaning and hot water flushing

buttons or fittings. Remove all contents from pockets.

for approximately 10 minutes, inserting hose end into

(3) Wear rubber boots.

tank openings on both sides of baffles.

This is

(4) Use cotton waste for cleaning purposes.

necessary to purge fuel vapors, all oil or sludge (if

Other material may generate static electricity.

present), contaminants, and loose rust.

d. Conduct a combustible vapor test reading to

determine if fuel tank is safe to repair, clean, paint, store

6. Prepare and Clean for Purging of Fuel Tanks. a.

or change material.

Completely drain each fuel tank compartment, all piping,

pumps, meters, filters, and segregators, as applicable,

and remove all accessory items, such as gages and

8. Rust Removal Procedure. a. Remove rust from

floats, which might entrap fuel.

tank, utilizing an alkaline electrolytic immersion rust

b. Close or seal all drains. (It may be necessary to

removal system (see table 1). The alkaline chemical

locally fabricate covers for some types of drains, but do

compound shall be a sodium hydroxide base and shall

not create a vacuum.)

not contain any cyanide compound. It shall conform to

c. Fill fuel tank and overflow for 5 minutes with cold

Type I of Spec MIL-C- 14460 or commercial equivalent.

water. Drain fuel tank completely.

(1) Stack small tanks upside down in basket.

d. Close or seal drains.

Large tanks can be suspended on hooks. Position with

e. For each 100-gallon capacity, add 40-fluid ounces

the drain opening in uppermost position to purge all air

of alkaline electrolytic sodium hydroxide base to the fuel

from tank. When immersed, insure that no air pockets

tank. (This is equivalent to 8-fluid ounces of concentrate

remain. Solution must be in contact with metal surfaces

for a 20-gallon fuel tank.)

to remove rust.

(2) Immerse tank in bath until all rust is removed.

CAUTION

This should range from 45 minutes to 1l/2 hours

Insufficient amount of chemical will result

depending on rust stage.

in an incomplete purging.

Accurate

(3) Remove tanks from bath and suspend

computations of amount of chemical to be

basket above bath until all solution is drained. A

added must be made prior to the purging.

temporary rust-inhibiting powder residue will protect the

Once purging has begun, do not stop until

tank from rusting again until the powder is removed by

process is complete.

water rinse. Inspect to insure all rust is removed.

f. Fill fuel tank to top with water-do not overflow.

b. Water rinse and air dry (preferably forced warm

g. Insert air line into fuel tank filler neck opening and

air) the tank interiors. Inspect to insure tank interior is

agitate solution with 3 to 5 psi of air for 5 minutes.

dry. This operation shall be performed immediately

Frequently move air hose around in tanks, covering as

preceding coating application.

much area as possible, especially near the bottom and

c. Alternate methods of rust removal are acceptable,

around baffles. Remove air line and drain solution from

provided they receive prior approval from the

fuel tank.

Maintenance Directorate (NMP), US Army Tank-

h. Fill fuel tank and overflow for 5 minutes with

Automotive Materiel Readiness Command, Warren, MI

cold water or until water is clear. Drain fuel tank com-

48090.

pletely.

9. Coating Application Instructions. Prior to coating

i. Conduct a combustible vapor test reading to

application the following precautions will be used.

determine if fuel tank is safe to repair, clean, paint, store

Safety.

Coating contains flammable and volatile

or change material. If combustible vapor test reading

indicates tank is not safe, repeat procedures as cited in h

solvents. Keep away from open sparks and flame.

Comply with all local safety regulations and

above.

manufacturer's instructions.

j. Fuel tanks installed on vehicles will be processed

Health Precautions. Use adequate ventilation and avoid

as cited above, with exception of disconnecting and

repeated or prolonged breathing of vapors and prolonged

plugging the fuel line at the fuel tank. If fuel tank repairs

contact with skin. When using solvents for cleanup, use

are to be made, work must be started im-

proper

precautionary

measures,

re-