REPAIR HULL BY WELDING Continued
Welding on foam-filled parts is PROHIBITED. Toxic fumes can result in death.
10. Do not weld or use too much heat in areas or carrier where sealing compound (WP 0542 00, Item 33), (WP 0542 00,
Item 36), or (WP 0542 00, Item 38) has been applied or is known to exist. If you must weld in these areas, remove
compound then clean area with cleaning compound (WP 0542 00, Item 9). After welding, apply new sealing compound
(WP 0542 00, Item 36), or (WP 0542 00, Item 38)
Foam-filled parts: Drivers compartment doors.
MAGNESIUM CASTING, FILING, AND GRINDING
Do not use water or foam-type extinguishers. These types of extinguishers will intensify a
Observe special safety precautions when filing or grinding magnesium castings. Fine particles of magnesium are a fire
hazard. See (page 0406 00-3) for a list of magnesium castings used on this carrier. Use the following precautions when
working with or near magnesium.
Use grinding equipment marked FOR MAGNESIUM GRINDING ONLY.
Do not allow magnesium dust or magnesium dust mixtures to accumulate. Keep area clean.
Keep tools used to work magnesium sharp.
Dispose of grinding sludge immediately.
Wear leather or smooth, fire-retardant clothing; brush frequently.
Keep fire extinguisher for magnesium handy.
MIG WELDING METHOD
MIG (Metal Inert Gas) Welding. This process uses a dc power source, control panel, and a welding gun. the gun feeds a
consumable bare electrode at a given rate into a molten pool beneath a blanket of protective inert gas. When an arc is set
up, a molten pool forms at once. Move the welding gun along the joint line at a rate that shapes the right size bead. The
covering of inert gas keeps air from polluting the weld zone. No flux is needed.
Contraction and Expansion. Aluminum welds contract about 6 percent in volume when they become solid after being
melted. Welding at a slow speed may cause too much heating of the area around weld. This will cause the metal to
expand too much. It will then shrink too much when it cools.