Preparation of material prior to welding

TM 5-5420-279-23

Preparation of material prior to welding

The following conditions apply:

CAUTION

Aluminum and aluminum alloys should not be cleaned with caustic soda or strong

cleaner with a pH above 10. The aluminum or aluminum alloy will react chemically

with these types of cleaners. Other nonferrous metals and alloys should be

investigated prior to using these cleaners to determine their reactivity.

(1)

All parts to be repaired and the associated parent metal are to be prepared by

removal of paint at least 50 mm around repair, degreasing thoroughly followed by wire

brushing before fitting and welding.

(2)

Wire brushes must be maintained in a grease free condition, and for aluminum must

have stainless steel bristles.

(3)

Run on/run off plates must be used wherever possible, unless there is a crater filling

facility on the welding set, or a suitable crater filling technique is used.

(4)

Any crater cracking (star cracking) should be removed by dressing. Removal of

excessive material can be replaced by welding as required.

NOTE

When dressing cracks try to avoid removing too much parent material as the

resulting repair by welding will reduce the number of permissible future repairs.

(5)

Welding wire must be kept clean, dry and dust free. When using a set that has stood

for some time unused, sufficient wire must be removed off the spool before welding to

avoid using contaminated wire.

(6)

Inter-run wire brushing is mandatory.

(7)

Double sided welds must be back chipped or back ground (NOT by any thermal

cutting process) as required, and the root run dye penetrant tested (section 3 c.) to ensure

all defects have been removed. All welding must be allowed to cool before welding the

second side or any subsequent weld runs.

Welding Conditions

(1)

The gas flow rates for welding should be set at:

(a)

1.6 mm wire 45-55 cu/ft/hr.

(b)

1.2 mm wire 35-45 cu/ft/hr.

These are both relevant for the use of Argon for Aluminum and Argon/CO2 for steel.

(2)

Only shaved or chemically cleaned welding wire (Section 4 Table 4-1, Items, 33, 34

and 41 to 49) should be used.

Appendix K Page 4