Fuel and Hydraulic Tanks Repair
100 SRM 449
CLEAN
WARNING
Special procedures must be followed when
large leaks or other repairs need welding or
cutting. All work must be done by authorized
personnel. If the tank is cleaned inside a build-
ing, make sure there is enough ventilation.
See the following manuals for additional infor-
mation:
• Safe Practices for Welding and Cutting Con-
tainers That Have Held Combustibles, Ameri-
can Welding Society, F4.1 - 1999.
• Safety In Welding and Cutting, American Na-
tional Standard, AWS Z 49.1 - 1999.
When cleaning the tank, do not use solutions that
make dangerous gases at normal temperatures or
when heated. Wear eye and face protection. Protect
the body from burns.
When cleaning with steam, use a hose with a mini-
mum diameter of 19 mm (0.75 in.). Control the pres-
sure of the steam by a valve installed at the nozzle of
the hose. If a metal nozzle is used, it must be made of
a material that does not make sparks. Make an elec-
trical connection between the nozzle and the tank.
Connect a ground wire to the tank to prevent static
electricity.
Steam Method of Cleaning
Use the following procedure to clean the tank with
steam:
1.
Remove all the parts from the tank. Install the
drain plug.
2.
Fill the tank 1/4 full with a solution of water and
sodium bicarbonate or sodium carbonate. Mix
0.5 kg (1 lb) per 4 liter (1 gal) of water.
3.
Mix the solution in the tank using air pressure.
Make sure all the surfaces on the inside of the
tank are flushed with the solution. Drain the
tank.
4.
Put steam into the tank until the tank does not
have odors and the metal is hot. Steam vapors
must come from all the openings.
5.
Flush the inside of the tank with boiling water.
Make sure all the loose material is removed from
the inside of the tank.
6.
Make an inspection of the inside of the tank. If it
is not clean, repeat Step 4 and Step 5 and make
another inspection. When making inspections,
use a light that is approved for locations with
flammable vapors.
7.
Put plugs in all the openings in the tank. Wait 15
minutes, then remove the inlet and outlet plugs.
Test a sample of the vapor with a special indi-
cator for gas vapors. If the amount of flammable
vapors is above the lower flammable limit, repeat
the cleaning procedures.
Chemical Solution Method of Cleaning
If the tank cannot be cleaned with steam, use the
following procedure:
1.
Mix a solution of water and trisodium phosphate
or a cleaning compound with an alkali base. Fol-
low the instructions given by the manufacturer.
2.
Fill the tank with the cleaning solution. Use com-
pressed air to mix the solution in the tank.
3.
Drain the tank. Flush the inside of the tank with
hot (boiling) water. Make sure all the cleaning
compound is removed.
4.
Make an inspection of the inside of the tank.
If the tank is not clean, repeat Step 1 through
Step 3. Make another inspection of the tank.
When making inspections, use a light that is ap-
proved for locations with flammable vapors.
5.
Check the tank for flammable vapors using
special indicator for gas vapors. If the amount
of flammable vapors is not below the lower
flammable limit, repeat the cleaning procedures.
ADDITIONAL PREPARATIONS FOR
REPAIR
If nitrogen gas or carbon dioxide gas is available, pre-
pare the tank for welding using these gases. See the
manual Safe Practices for Welding and Cutting Con-
tainers That Have Held Combustibles by the Ameri-
can Welding Society, F4.1 - 1999. If these gases are
not available, another method using water can be
used as follows:
1.
Fill the tank with water to just below the point
where the work will be done.
Make sure the
space above the level of the water has a vent.
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