TM 55-1520-240-23-1
1-83
CLEAN ALUMINUM AND ALUMINUM ALLOY PARTS (AVIM)
(Continued)
1-83
NOTE
This procedure is used when an
extremely clean surface is necessary,
such as prior to welding, or when
bonding large areas of aluminum.
Separate solutions must be used for
parts to be welded and parts to be
bonded.
1.
Prepare solution of sulfuric acid (E23) and
sodium dichromate (E357) as follows:
a.
Pour cold water into a tank.
b.
Add 40 ounces of sulfuric acid (E23) to each
gallon of water in tank.
c.
Add 4-1/2 ounces of sodium dichromate
(E357) to each gallon of water in tank.
d.
Stir solution until sodium dichromate
dissolves.
2.
Prepare solution of Oakite No. 61 (E249) as
follows:
a.
Add 7 ounces of Oakite No. 61 (E249)
crystals to each gallon of water used. Stir
water while adding crystals.
b.
Heat solution to 175º to 185ºF (70.5º to
85ºC) to dissolve crystals.
Naphtha (E245) is combustible and
toxic. It can irritate skin and cause
burns. Use only with adequate
ventilation, away from open flame. In
case of contact, immediately flush
skin or eyes with water for at least
15 minutes. Get medical attention
for eyes.
3.
Before cleaning parts, degrease them with cloths
(E120) soaked in naphtha (E245) or equivalent.
4.
Clean parts as follows:
a.
Immerse part in solution of Oakite No. 61
(E249) 5 to 10 minutes. Maintain a solution
temperature of 160º to 210 ºF (71º to 99ºC)
for this period.
b.
Remove part from solution. Rinse with water.
c.
Inspect for breaks in water film. If break
occurs, repeat degreasing procedure step 3.
Then repeat steps 4a, 4b, and 4c.
d.
Immerse parts in solution of sulfuric acid
(E23) and sodium dichromate (E357) 10 to
20 minutes. Maintain solution temperature
of 150º to 170ºF (66º to 77ºC) for this period.
e.
Remove part from solution, rinse thoroughly
with water. Dry with clean, dry filtered hot air.
Do not exceed 140ºF (60ºC).
f.
Handle clean parts with clean gloves. Wrap
part with barrier material (E80).
g.
If recleaning is necessary, repeat step 4.
However, in step a, immerse part only 2-1/2
to 5 minutes. Also, in step d, immerse part
only 5 to 10 minutes.
NO BREAK - WORK HARDER
NO BREAK - WORK HARDER
FOLLOW-ON MAINTENANCE:
None
END OF TASK
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