MIL-DTL-62749A
3.13 Workmanship.
3.13.1 Steel fabrication. Steel may be cut by shearing, sawing or flame cutting. Burned
surfaces of flame cut material shall be ground or machined to remove cooling checks. All bends
shall be made by use of metal dies or fixtures to insure uniformity in size and shape. All burrs
shall be removed.
3.13.2 Aluminum fabrication. Aluminum used in the fabrication of the component shall
be free from kinks and sharp bends. Straightening of material shall be done by methods that will
not cause injury to the metal. Surfaces and edges of all finished members shall be smooth and
free from kinks, bends and winds. All forms of a major character shall be made with metal dies
or fixtures to insure uniformity of size and shape. Sharp instruments shall not be used for
marking bend lines. Aluminum shall not be cut by methods using heat. Aluminum less than
3/8 inch thick may be cut by shearing; aluminum 3/8 inch thick and over shall be cut by routing
or by high speed saws. Shearing and sawing shall be done neatly and accurately. Material used
must comply with the original material mechanical properties.
3.13.3 Bolted connections. Bolt holes shall be accurately formed and shall have the
burrs removed. Washers or lockwashers shall be provided where necessary. All fasteners shall
be correctly torqued according to the specifying document and shall have full thread
engagement. Bolts shall protrude not more than two full threads.
3.13.4 Welders and welding.
3.13.4.1 Welders. Before assigning any welder or welding operator to welding work
covered by this specification, the contractor shall obtain certification that the welder or welding
operator has passed qualification tests as prescribed by either of the following listed codes for the
materials joined and the type of welding operation to be performed and that such qualification is
effective as defined by the particular code:
AWS D1.1 - Structural welding Code - Steel.
AWS D1.2 - Structural Welding Code - Aluminum.
ASME Boiler and Pressure Vessel Code, Section IX, Qualification Standard for
Welding and Brazing Procedures, Welders, Brazers, and welding and Brazing
Operators.
3.13.4.2 Welding. The surfaces of parts to be welded shall be free from dirt, scale, paint,
grease and other foreign matter. Welding shall be done by the shielded metal-arc or gas metal arc
(GMAW, which is also called metal insert gas or MIG). All welded parts shall be free from slag,
flux, welded spatter, cracks and other imperfections that may reduce the effectiveness of the part.
Work shall be positioned for flat welding when practicable. Before welding over previously
deposited weld metal, all traces of slag shall be removed and the deposit and adjoining base
metal shall be wire brushed clean. Tack welds shall be subject to the same quality requirements
as final welds. Procedure and sequence shall be such that distortion and shrinking will be held to
a minimum.
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