MIL-DTL-29229B(YD)
3.6 Drawings. The switches and frogs shall be constructed in accordance with NAVFAC
drawings listed in 2.1. Drawings forming a part of this specification are engineering design
drawings. The contractor shall be responsible for preparing shop drawings. Where tolerances
provided could cumulatively result in incorrect fits, the contractor shall provide tolerances within
those prescribed on the drawings to insure correct fit, assembly, and operation of the items.
Proposed changes by the contractor to the government furnished design drawings shall be
approved by the contracting officer. No deviation from the prescribed dimensions or tolerances
shall be permissible without prior approval of the contracting officer.
3.7 Construction. Switches and frogs shall be constructed to the dimensions and tolerances
shown in applicable drawings and as specified herein.
3.7.1 Alternatives for rigid frog construction. The following two alternative methods of
construction are shown in NAVFAC drawings 1403331, 1404038, and 1404039. Alternative "A"
consists of a composite construction of ASTM A 36 steel topped by a plate of ASTM A 514 steel
which has been case hardened to not less than 350 Brinell hardness. Alternative "B" construction
requires a hard facing, as shown in the drawings and described in 3.4.3, on the base material of
ASTM A 514 steel plate.
3.8 Finish. Unless otherwise specified herein or on the applicable drawings, surfaces shall be
machine finished. Faces of sliding surfaces shall have an average roughness of 63 microinches
(1.6 µm) as defined by ANSI B46.1 and ANSI Y14.36.
3.9 Identification marking. Identification marking shall be cast into each unit in a location easily
visible after installation. Required information shall include as a minimum:
a.
Manufacturer and location of plant.
b.
Type, class, and style.
c.
Date of manufacture.
d.
Radius of turnout for switches.
e.
Angle (for rigid or turntable frogs).
f.
Radius of curvature for radius type frog.
g.
Applicable rail section(s).
3.10 Workmanship.
3.10.1 Steel fabrication. The steel used in fabrication shall be free from kinks, sharp bends, and
other conditions which would be deleterious to the finished product. Manufacturing processes
shall not reduce the strength of the steel to a value less than intended by the design.
Manufacturing processes shall be done neatly and accurately. All bends shall be made by
controlled means to ensure uniformity of size and shape.
3.10.2 Welding. Welding procedures shall be in accordance with a nationally recognized welding
code. The surfaces of parts to be welded shall be free from rust, scale, paint, grease, or other
foreign matter. Welds shall be of sufficient size and shape to develop the full strength of the parts
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