Closure.

(a) Closure for the wooden protective jacket is provided by the steel reinforcing rods. The end cap (lid) must fit tightly to the body of the jacket to prevent a heat path to the inside of the jacket. The lid joint for specifications 20WC-3, 20WC-4, 20WC-5, and 20WC-6, may not be coplanar with the end of the inner containment vessel.

(b) Specifications 20WC-2 and 20WC-6. Locking ring closure, if used, must conform to § 178.354-4. Flanged closure, if used, must have at least 8 steel bolts (at least 6 mm (0.25-inch) diameter for 20WC-2 or 1.2 cm (0.50-inch) diameter for 20WC-6) and lock nuts (or equivalent device), spaced not more than 13 cm (5 inches) between centers.

[Amdt. 178-35, 39 FR 45252, Dec. 31, 1974. Redesignated by Amdt. 178-97, 55 FR 52716, Dec. 21, 1990, as amended at 63 FR 37462, July 10, 1998; 66 FR 45387, Aug. 28, 2001]