TM 55-607/NAVSEA OP 3221 Rev 2
CHAPTER 7
STANDARD SECURING STRUCTURES AND REQUIREMENTS
7-1. General
This chapter summarizes construction details and materials used in securing military explosives for the purpose of
preventing movement and damage during transportation. The fundamental structures and requirements described herein
are already established by Federal regulations or are used regularly in dunnaging operations. Consequently, the
procedures do not vary significantly with the loading activity, type of cargo, or hull configuration.
7-2. Decking
a. General Requirements. Decking, commonly known as flooring, will be laid over metal decks or tank tops, as
required, to protect military explosives. However, decking is not required when decks or tank tops are coated with
appropriate nonmetallic materials, such as mastic, or if the units are palletized on wood pallets. The entire interior or
class "A" magazine must be wood and, therefore, must be completely floored regardless of pallet construction.
b. Effect of Decking. Metallic contact constitutes a transportation hazard for several reasons. In the event of loss
of stow integrity, spark generation from metal-to-metal sliding contact between the deck and unit loads poses serious
danger of fire and/or explosion. Of less obvious effect is the influence of flooring on the integrity of the securing system.
Friction is the resistance that is encountered when two solid surfaces slide or tend to slide over each other and, under
moderate pressures, is proportional to the normal (perpendicular) load on the rubbing surfaces. Hence, friction acts in
addition to restraint that is provided by securing structures and dunnaging to resist movement that would otherwise result
from forces generated by ship motions. The amount of frictional resistive force would depend on surface finish,
atmospheric dust and humidity, oxides on the deck, temperature, vibration, and surface contaminants such as grease
and water. These factors are all present in the holds of cargo ships, and essentially their cumulative effect is a reduction
in surface friction, particularly for metal-to-metal surfaces such as metal pallets in contact with the metal deck. Wood
flooring serves as an absorbent of contaminants and minimizes the undesirable effects of poor surface conditions.
c. Strip Decking. Since the main purpose of decking is to prevent metal-to-metal contact between the deck and the
unit load, it is necessary to install, as a minimum, strip decking in compartments where metal pallets or the strapping of
wooden skids bound with metal straps would otherwise contact the deck. Figure 7-1 illustrates the use of strip decking,
also referred to as strip flooring. Since the strip decking bears only compressive loads, 1 by 6-inch lumber is adequate
for stripping purposes. Strip decking is normally laid butt-to-butt. However, instead of being cut, ends may be
overlapped side-by-side when they are too long. Stripping should be positioned crosswise to the pallet skids, as shown,
to minimize any possibility of the unit load's being displaced from the stripping in transit.
7-1
