When, in order to eliminate grain heeling moments in partly
filled compartments, strapping or lashing is utilized, the securing
may, as an alternative to the method described in A 17, be accomplished as follows:
-
.1 The grain shall be trimmed and levelled to
the extent that it is very slightly crowned along the fore and aft
centreline of the compartment.
-
.2 The entire surface of the grain shall be covered
with burlap separation cloths, tarpaulins, or the equivalent. The
covering material shall have a tensile strength of not less than 1,344
N per 5 cm strip.
-
.3 Two layers of wire reinforcement mesh shall
be laid on top of the burlap or other covering. The bottom layer is
to be laid athwartships and the top layer is to be laid longitudinally.
The lengths of wire mesh are to be overlapped at least 75 mm. The
top layer of mesh is to be positioned over the bottom layer in such
a manner that the squares formed by the alternate layers measure approximately
75 mm x 75 mm. The wire reinforcement mesh is the type used in reinforced
concrete construction. It is fabricated of 3 mm diameter steel wire
having a breaking strength of not less than 52 kN/cm2 welded
in 150 mm x 150 mm squares. Wire mesh having mill scale may be used
but mesh having loose, flaking rust may not be used.
-
.4 The boundaries of the wire mesh, at the port
and starboard side of the compartment, shall be retained by wood planks
150 mm x 50 mm.
-
.5 Hold-down lashings, running from side to side
across the compartment, shall be spaced not more than 2.4 m apart
except that the first and the last lashing shall not be more than
300 mm from the forward or after bulkhead, respectively. Prior to
the completion of the loading, each lashing shall be positively attached
to the framing at a point approximately 450 mm below the anticipated
final grain surface by means of either a 25 mm shackle or beam clamp
of equivalent strength. The lashing shall be led from this point over
the top of the boundary plank described in A 18.1.4, which has the
function of distributing the downward pressure exerted by the lashing.
Two layers of 150 mm x 25 mm planks shall be laid athwartships centred
beneath each lashing and extending the full breadth of the compartment.
-
.6 The hold-down lashings shall consist of steel
wire rope (19 mm diameter or equivalent), double steel strapping (50
mm x 1.3 mm and having a breaking load of at least 49 kN), or chain
of equivalent strength, each of which shall be set tight by means
of a 32 mm turnbuckle. A winch tightener, used in conjunction with
a locking arm, may be substituted for the 32 mm turnbuckle when steel
strapping is used, provided suitable wrenches are available for setting
up as necessary. When steel strapping is used, not less than three
crimp seals shall be used for securing the ends. When wire rope is
used, not less than four clips shall be used for forming eyes in the
lashings.
-
.7 During the voyage the hold-down lashings shall
be regularly inspected and set up where necessary.