A common place for leakage is around dog
spindles where the spindles pass through doorframes.
There is a stuffing box for each dog spindle. The
packing in the stuffing box prevents leakage. Inspect
the stuffing boxes frequently to ensure that they are in
good condition. Tighten the packing gland to give the
correct compression of the packing. Repack the dogs
when the packing gets hard or deteriorates with age.
Occasional adjustment of the dogs is required to
compensate for the wearing down of the wedges,
which the dogs bear down on. When wedges become
Figure 3-14. Watertight door parts.
badly worn, you should either build them up again by
gas brazing or replace them.
Gaskets for bolted manhole covers and other
For a door or hatch to be watertight when it is
bolted plates differ in size, shape, and material from
dogged, the knife-edge or bearing surface of the
those used with doors, hatches, scuttles, and dogged
closure must be centered on the gasket. The knife-edge
manholes. Bolted manhole covers and bolted plate
must also bear down on the gasket firmly and evenly
gaskets should be renewed whenever they are found to
all-around for the closure to be watertight. The door
be in poor condition when the cover is removed.
will not be watertight if either the door or the frame is
Replacement of these gaskets at this time is
particularly important since you cannot tell anything
warped. Also, the closure will not be watertight if the
about the condition of the gasket when the
door or hatch is not located correctly on its hinges with
manhole/plate is bolted down. The gasket may appear
respect to the doorframe. Other factors governing a
to be perfectly all right when actually it is in a poor
closure's watertight feature are whether or not the
condition and is providing a channel for progressive
knife-edge is straight and even, whether the retainer
flooding. The replacement gaskets must be of the
strips are secured firmly in place, and whether the dogs
proper material. The manhole/plate bolts must be
are adjusted to provide equal pressure on all of the
tightened up evenly all-around. A loosely secured
wedges when the dogs are snugly set up. If any of these
manhole cover can be blown off by an explosion,
parts have an incorrect fit, the frame or knife-edges
whereas a cover that is tightly secured will not.
may come into contact with the metallic parts of the
Be careful when moving heavy objects, such as
closure and thus allow the closure to be closed in a
and hatches. If you are careless, you can distort the
Some ventilation ducts have covers to isolate the
knife-edge or bearing surface of the closure by the
ventilation system. The gaskets on these covers are
impact of the heavy object.
subject to the same kinds of failure that access closure
The compression between a knife-edge and a
gaskets are. Many ventilation closures and valves
gasket should be checked periodically. If necessary,
installed in the ventilation ducts lack tightness because
adjust the closure until the compression specified in
of improper seating. These fittings should be inspected
the manufacturer's technical manual is reached.
on a regular basis. If you lubricate and maintain the
Watertight doors and hatches will retain their
fittings on a routine basis, the fittings will stay in good
efficiency longer and will require less maintenance if
working condition indefinitely.
you open and close them properly. When you close a
Throughout the ship, electric cables pass through
door or hatch, secure a dog that is on the OPPOSITE
many watertight boundaries. The watertight integrity is
SIDE of the closure from the hinges. Use just enough
maintained by passing each cable through a packed
pressure to keep the door closed. Next, secure two dogs
stuffing tube (fig. 3-15). Usually, several cables will
on the hinge side until snug. Then secure all the
pass through a deck or bulkhead in a small area known
remaining dogs evenly to ensure an even compression
as a multi-cable transit frame (fig. 3-16). The stuffing
all-around. When loosening dogs on watertight doors
tube nearest the center of the group can be repacked only
or hatches, loosen the dogs nearest the hinges first.
with a great deal of difficulty. It is vital, however, that the
This will keep the closure from springing and makes it
packing be replaced when necessary. If you allow bad
easier to operate the remaining dogs.