TAKEN TO KEEP ACID OUT OF FAYING SURFACES, BUTT JOINTS, SEAMS,
CREVICES, ETC.
(1)Mask adjacent areas to prevent brighteners from contacting magnesium,
anodized aluminum, glass, plexiglass, fabric surfaces and steel.
WARNING: WEAR ACID-RESISTANT GLOVES, PROTECTIVE MASK, AND PROTECTIVE CLOTH-ING WHEN WORKING WITH ACID COMPOUNDS. IF THE ACID ACCIDENTLY CON-TACTS THE SKIN OR EYES, FLUSH OFF IMMEDIATELY WITH A CONSIDERABLE
AMOUNT OF CLEAN WATER. CONSULT A PHYSICIAN IF EYES ARE AFFECTED OR
IF SKIN IS BURNED.
(2)Dilute the phosphoric acid base corrosion removing compound according to
manufacturer's instructions. Mix the compound in wood, plastic or plas-tic lined containers. Do not add water to acid; always add acid to
water.
(3)Apply diluted solution to corroded areas by spraying or with a sponge or
brush. Apply with a circular motion, starting from lower surfaces and
working upward to minimize runs and streaks.
(4)Leave the solution on from 5 to 30 minutes, depending on the temperature
and the amount of corrosion present. Agitate occasionally with shortfi-bered acid resistant brush. Do not allow solution to dry on the surface,
as streaking will result.
(5)Rinse with a stream of water or wipe off with clean, moist cloth fre-quently rinsing the cloth in clear water.
(6)Dry area with clean, dry cloth and inspect area for corrosion.
Volume 1
20-40-00
Page 11 OCT 01/01
CAUTION: DO NOT REPEAT OPERATION MORE THAN ONCE. IF CORROSION STILL REMAINS
AFTER SECOND ATTEMPT, PROCEED TO MECHANICAL REMOVAL METHODS.
(7)Repeat steps 3 thru 6 if any corrosion remains.
(8)Fair depressions resulting from rework per par. 7.C., and surface finish
with 400 or 600 grit abrasive paper. Select proper abrasive per Fig. 3.
(9)Clean reworked area.
(10)Determine depth of faired depression per par. 7.D., to ensure that
rework depth limits have not been exceeded.
(11)Treat reworked surface as indicated in 20-50-00.
9. Corrosion Removal Procedures for Magnesium Alloys
A. General. Magnesium is lightweight, but is the most chemically active metal.
It is highly susceptible to corrosion when failure of the protective coating
has occurred. To preclude serious structural damage, early detection and
prompt corrective action must be taken. The beginning of corrosion is indi-cated by a lifting of the paint film and white spots on the surface, which
rapidly develop into snow-like mounds or whiskers. Procedures for corrosion
removal by either mechanical or chemical methods are provided in the follow-ing paragraphs.
WARNING: PERSONNEL USING THESE PROCEDURES SHALL OBSERVE THE SAFETY PRECAUTIONS
AND PROCEDURES PER PAR. 2.
SMALL PARTICLES AND FINE SHAVINGS OF MAGNESIUM IGNITE EASILY AND
PRESENT AN EXTREME FIRE HAZARD. MAGNESIUM DUST IS HIGHLY FLAMMABLE 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 防腐手册 CORROSION PREVENTION MANUAL 第二册 一般信息(25)
