TM 55-607/NAVSEA OP 3221 Rev 2
CHAPTER 5
APPROVED MATERIALS AND SPECIFICATIONS
5-1. General
a. The basic specification requirements for securing materials are developed from 46CFR146, which defines the
basic structures and materials. It does not, however, provide sufficient details for procurement purposes, and there is no
single specification that spells out the total requirements for the physical composition of dunnaging materials to be used
in loading military explosives aboard merchant ships. Each type of securing material used is covered by individual
specifications of either Government or commercial origin.
b. Since a primary purpose of this publication is to standardize securing practices and procedures, there must first
be some degree of standardization in the dunnaging materials used. For this reason, reference publications are cited in
the material descriptions to serve as guides in obtaining or recognizing securing materials that have proved to meet the
requirements of availability, utility, strength, and reasonable cost. The referenced publications also form the basis for a
set of common terms and definitions that are needed to clarify local terminologies, which have developed because of the
widely dispersed geographical locations of material users and producers. This is particularly true in the case of lumber
and plywood, where such parameters as quality, species of wood, and sizes are established in grading rules issued by
lumber manufacturers' associations or their affiliated inspection services; in the commercial standards issued by the
Bureau of Foreign and Domestic Commerce of the US Department of Commerce; and in Federal Government
specifications issued by the Federal Supply Board (formerly Federal Specifications Board). The latter covers
Government purchases in governmental and military specifications formulated and issued for specific products by the
Department of Defense. Should the user of this publication require a more detailed knowledge of the specific dunnaging
material than is provided herein, the referenced publications will also serve this purpose.
c. The following descriptions cover all the materials specified for use in dunnaging by the regulations in 46CFR146,
as well as other materials not directly specified but commonly used in complying with the requirements of applicable
regulations. Materials specified by regulation that are considered the ship's responsibility are not discussed; that is,
sweatboards, Ys-inch wire-mesh screening to cover ventilators in magazines, and blank flanges installed on the suction
side of bilge pump manifolds for chemical ammunition storage.
5-2. Wood
a. General Classification. Native species of trees are classified generally as hardwoods or softwoods. Normally,
softwood should be used for dunnaging because of its availability, utility, reasonable cost, ease of cutting and fastening,
and adequate strength characteristics. This preference does not exclude the use of acceptable grades of hardwood in
areas where local softwood is not available (a situation common to many oversea ports). Because of its relatively short
duration of use, softwood is not preserved or fireproofed. Many species of softwood are available for securing
explosives, and the species selected at a particular loading activity will vary based on availability and cost. Common
commercial softwood species are listed in appendix B.
b. Applicable Specifications. Federal Specification MM-L-751, Softwood Lumber, covers the requirements for
softwood used in shipboard dunnaging.
c. Grades of Common Boards. Five numerical grades of common boards are provided for in the American Lumber
Standards (some lumber associations such as the West Coast Lumber Inspection Bureau (WCLIB) and the Western
Wood Products Association (WWPA) grade common boards in only four grades: construction, standard, utility, and
economy). Grade 1 is classed as suitable for better type construction and grade 2 for good standard construction. For
sheathing and dunnaging ammunition, use grade 2 softened lumber (except where unavailable) that is sound and free
from crossgrain knots, checks, or splints, which impair the strength of the lumber or interfere with adequate nailing. It is
recognized that significant variations of quality can occur between like grades. Therefore, conservation by rated grade 3
lumber that meets the above quality standards may be used in place of grade 2.
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