Preparation of Cracked Areas. - TB-9-2510-242-400069

TB9-2510-242-40

to twice the base metal thickness. The depth of the groove shall be a minimum of 1/32 inch beyond the depth of

the crack. Grinding of aluminum, except for final weld contouring and finishing operation, is not recommended.

When grinding is unavoidable, use non-loading type abrasives specifically for aluminum. As a last resort, air

carbon arc cutting may be used for gouging if available; however, the arc should not be used to remove all the

metal in the joint. Leave a minimum of 1/4 inch of material and remove it with a grinder. Note: carbon residue

must be removed. A degreased stainless steel wire brush may be used to clean cracks and joints.

b. Avoid overheating the base metal when removing defective material. High heat may result in a serious loss

of the material properties.

c. Avoid undercutting, nicking or removing neighboring weld material or undamaged base metal. Metal

must later be added to the surface to compensate for any deficiency in size.

d. Prepare surfaces to be welded. Prepare edges and joint surfaces to be welded by shearing, swing plasma arc

cutting, chipping, planing, milling, or routing. Surfaces to be welded shall be smooth, uniform, and free of fins,

tears and cracks. A degreased stainless steel wire brush may be used to clean cracks and joints.

WARNING

Do not inhale Chemical Agent Resistant Coating (CARC) paint particles. CARC paint is toxic.

Use breathing respirator while removing paint.

CAUTION

If material is not welded promptly, oxides which readily form on all aluminum surfaces, must be

removed before welding.

E-15