MIL-DTL-3390H
3.2.8 Plastic, nylon. The plastic dee rings shall be molded from virgin nylon conforming
to designation PA0181 of ASTM D4066. Clean unburned plastic material in the form of
imperfect parts, sprues, runners, or other scrap of the same composition as the virgin material,
and produced in the molding or finishing operation, may be reground and mixed with the virgin
material specified. When reground material is mixed with the virgin material, the reground
material shall not exceed a level of 25 percent by weight of the blended mixture.
3.2.9 Recycled, recovered, or environmentally preferable materials. Recycled,
recovered, or environmentally preferable materials should be used to the maximum extent
possible provided that the material meets or exceeds the operational and maintenance
requirements and promotes economically advantageous life cycle costs.
3.3 Design and construction. The design and construction of the rings shall conform to
drawings 4-1-454, and 4-1-455, and the requirements specified herein. All burrs, sharp edges,
and slivers shall be removed before application of any finish.
3.3.1 Class 1 rings. At the option of the supplier, class 1 rings shall be cast of the brass
material is shown on the applicable drawing. Available configurations are A, B, E, F, G, H, J, K,
L, W, and X. After forming to shape and locating the joint as shown on the drawing, the joint
shall be joined by butt resistance welding or brazing. The completed joints shall be smooth,
round, and free of cracks, burns, or reduced areas. The rings shall be free of porosity, blowholes,
warp, and clearly noticeable digs and gouges.
3.3.2 Class 2 rings. Class 2 rings shall be fabricated of the steel wire specified in 3.2.4.
After forming to shape and locating the joint as shown on the drawing, the joint shall be butted
and welded. Unless otherwise specified (see 6.2), configuration "A" rings shall be butted only.
The welds shall be sound, not porous, and free from cracks, burns, or reduced areas. The welds
shall be ground smooth and free of rough edges. The rings shall be free of porosity, blowholes,
warp, and clearly noticeable digs and gouges. Available configurations are indicated on the
drawings by the letters A, D, E, F, H, K, L, M, R, T, U, V, and X.
3.3.3 Class 3 rings. Class 3 rings shall be cast from the malleable iron specified in 3.2.5.
Available configurations are A, B, E, F, G, J, W, and X. The rings shall be free of porosity,
blowholes, warp, and clearly noticeable digs and gouges.
3.3.4 Class 4 rings. Class 4 rings shall be cast from the nickel-silver alloy specified in
3.2.6, conforming to configuration C. The rings shall be free of porosity, blowholes, warp, and
clearly noticeable digs and gouges.
3.3.5 Class 5 rings. Class 5 rings shall be molded of the plastic specified in 3.2.8. The
available configuration is X.
3.3.6 Rollers. The rollers required for configurations U, V, and X (style 2) shall be
fabricated of the brass sheet or strip specified in 3.2.2 and to the dimensions shown on the
drawings. After assembly to the straight section of the ring, the rollers shall rotate freely without
binding and the joint of the roller along its entire length shall be butted evenly.
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