TM 55-607/NAVSEA OP 3221 Rev 2
(6) The allowable load in lateral resistance for a nail or spike driven into the end grain (parallel to fibers) will be
two-thirds of the allowable load for nails driven into the side grain.
(7) The end distance, edge distances, and spacing of nails and spikes shall be such as to avoid unusual
splitting of the wood. Generally, no nail shall be driven closer to the edge than half the thickness of the piece holding the
nailhead. Figure 6-23 illustrates nail placement in relation to thickness of stock.
(8) When pieces of lumber are of different thicknesses, the nailhead should be in the thinner piece, as shown
(9) Nailheads should be driven flush with the nailing surface. In any case, the nailhead should not be driven
deeper than one-eighth the thickness of the head retaining piece.
(10) A staggered pattern should be used when nails aredriven in boarding or flooring. Nails in the same row
should be separated by a minimum of 4 inches, as shown in figure 6-23.
(11) Caution should be exercised when nails are being driven near packages of explosives. Nails not directed
toward the package may be deflected into the unit load by a nonyielding substance. In cases where nailing of lumber
may present hazards, alternate methods of securing must be approved by authorized inspectors.
WARNING
Never nail lumber directly to unit loads of explosives. Hammer blows must never directly contact
the explosives package.
(12) When structures such as kickers (which are supported by nails and a functional force-fit) are toenailed, at
least two nails will be driven in three sides at each end of the nailed piece (fig 6-23). The allowable withdrawal load in
toenailed joints is equivalent to two-thirds of the allowable withdrawal load for the side grain (see table C-3).
c. Wood Screw Joints. Although not commonly used in dunnaging operations, mainly because of the increased
time requirements for installation, wood screws are acceptable for construction purposes. Tables C-5 and C-6 provide a
tabular summary of allowable withdrawal and lateral loads for common wood screws. Withdrawal resistance of screws is
a function of the effective penetration; that is, the length of the threaded portion of the screw, in the receiving piece. The
following general rules apply to the use of wood screws in the shipyard-securing of ammunition and explosives:
(1) Allowable loads for a single screw, as specified in appendix C, can be summed to determine the total
allowable load for more than one screw.
(2) Normal allowable loads for screws, as specified in appendix C, can be summed to determine the total
allowable load for more than one screw.
(3) Screws used for fastening purposes in the interior of a class "A" magazine must be countersunk below the
surface of the wood.
(4) Lead holes should be prebored to accept screws.
(5) Screws inserted in lead holes should be turned wth a screwdriver; hammering is not permissible.
i
(6) Soap or other lubricant may be used sparingly on screws, or in lead holes, to facilitate insertion and to
prevent damage to the screw.
(7) Sufficient spacing, end distances, and edge distance should be provided to prevent splitting of the
dunnage.
(8) For lateral resistance, penetration of the screw into the main member should be approximately seven
diameters to achieve maximum loads. Penetration depth of less than four diameters is not recommended.
(9) Screws should not be loaded in withdrawal, particularly from end grain. Lateral load capacity of screws in
the end grain must be reduced by one third.
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