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|  MIL-C-52972A(ME)
3.18.2 Metal fabrication. Metal used in fabrication shall be free from kinks
and sharp bends. The straightening of material shall be done by methods that
will not cause injury to the material. Corners shall be square and true. Flame
cutting, using tips suitable for the thickness of the steel may be employed
instead of shearing and sawing. All bends shall be made with controlled means
to insure uniformity of size and shape. Precaution shall be taken to avoid
overheating. Heated steel shall be allowed to cool slowly. External surfaces
shall be free of burrs, sharp edges and corners, except when sharp edges or
corners are required or where they are not detrimental to safety.
3.18.3 Welding. The surfaces of parts to be welded shall be free from rust,
scale, paint, grease, mill scale that can be removed by chipping and wire
brushing and other foreign matter. Welds shall transmit stress without
permanent deformation or failure when the parts connected by the welds are sub-
jected to proof and service loading. Parent materials, weld filler metals, and
fabrication techniques shall be as required to enable the compressor unit to con-
form to the examination and test requirements specified in section 4. Parts to
be joined by fillet welds shall be brought into as close contact as possible and
in no event shall be separated by more than 3/16 inch, unless appropriate
bridging techniques are used. Unless otherwise specified (see 6.2), the welding
process used in fabrication of the compressor unit shall be at the option of the
contractor.
3.18.4 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 type of welding operations to be
performed and that such qualification is effective as defined by the particular
code:
ASME Boiler and Pressure Vessel Code, Section IX, Welding and Brazing Quali-
fications.
AWS, D1.1 Structural Welding Code - Steel.
Contractors who only make horizontal welds need not qualify welders for "all
position welding". The government reserves the right to require recertification
of any welder or welding operator. The certification shall be made available
for review by the contracting officer or his representative upon request.
3.18.5 Bolted connections. Boltholes shall be accurately formed and shall have
all burrs removed. Washers and lockwashers shall be provided where necessary.
Matching thread areas securing bolts or capscrews shall be of sufficient
strength to withstand the tensile strength of the bolt. All fasteners shall be
correctly torqued and shall have full thread engagement.
3.18.6 Riveted connections. Rivets shall fill the hole completely. The upset
rivet heads shall be full, neatly made, concentric with the rivet holes and in
full contact with the surface of the member.
3.18.7 Machine work. Tolerances and gages for metal fits shall conform to the
limits specified herein and to the standards of the industry.
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