valves to isolate the system to be opened, and tag these
valves to ensure they remain shut while you are working
on the equipment. Wear proper protective clothing. Do
not try to take shortcuts and do not skylark. Carelessness
has been a factor in nearly all reported mishaps
involving steam. Observe all appropriate precautions.
CLOSED COMPARTMENTS AND
UNVENTED SPACES
Never enter a closed space until it is certified
safe by a gas free engineer.
Closed compartments may contain hidden
dangers, both to yourself and to the ship as a whole. One
possibility is toxic or explosive gases. After these
spaces are opened, your gas free engineer will make
sure that it s safe for you to work there.
If the ship’s been damaged, other dangers may
exist. The manhole access cover to a damaged tank or
compartment might be all that’s preventing flooding.
Additionally, water entering a closed compartment
pressurizes the air already there. Don’t try to open a
pressurized compartment or void without venting the
pressure first. If you don’t vent the pressure first, the
hatch cover/access will fly open violently, possibly
injuring you or a shipmate. Check with your supervisor
for help in learning to recognize these and other
hazards.
Consider all compartments dangerous if they’ve
been closed for any length of time. If the bulkheads,
deck, or overhead are rusted, they have absorbed
oxygen from the air. This means there may not be
enough oxygen left for you to breathe. If the
compartment was painted before it was closed, the
hardening paint has absorbed oxygen and given off
carbon monoxide. Carbon monoxide is particularly
dangerous because it gives no warning. If you’re
working in a compartment that’s been closed and you
notice a sudden feeling of weakness, drowsiness, or a
slight headache, call for help and get to fresh air.
In storage compartments, several toxic gases may
be generated by mildewing or rotting foodstuffs or by
materials such as cloth, leather, and wood. Mildewing
and rotting are speeded up when the space is warm and
humid, such as when a ship is cruising in the Tropics or
when an area has been flooded as a result of damage or
accident.
Carbon dioxide is frequently found in refrigerator
spaces, even though the spaces are undamaged and the
foodstuffs are still good. This condition results from
lack of ventilation and the fact that foods slowly absorb
oxygen and give off carbon dioxide. If personnel stay in
such spaces longer than a few minutes at a time, they
may be overcome and eventually suffocate.
Sulfur oxides are acrid, corrosive, poisonous gases
produced when fuels containing sulfur are burned. For
example, aboard ship the primary producer of sulfur
oxides is fuel oil, which contains sulfur as an impurity.
Government agencies and industries have sought to
reduce sulfur oxide emissions in three ways:
1. Switching to low-sulfur fuels (those with less
than 1% sulfur).
2. Removing sulfur from fuels entirely.
3. Removing sulfur oxides from combustion
gases.
To reduce the sulfur oxide problem on ships, the Navy
developed a fuel oil called Navy distillate fuel.
Sulfur oxides produce an offensive odor and can
cause eye and lung irritation. Tanks that have held
petroleum products and compartments in which oil,
gasoline, solvents, and organic products that have been
spilled will contain the vapors of these products.
Tanks that have held petroleum products, and
compartments in which oil, gasoline, solvents, and
organic products have been spilt, will contain the vapors
of these products.
You must assume that any closed space, double
bottom, tank, cofferdam, pontoon, or void contains
gases that can poison or suffocate you or can explode.
(NOTE: Never enter any such space until it has been
thoroughly ventilated and checked by a gas free
engineer to make sure there is no danger of poisoning,
suffocating, or igniting flammable gases.) Before
entering a closed space, make sure that it’s been
ventilated for 24 hours. Also, the gas free engineer must
certify the safety of the space and recertify it every 8
hours while personnel are working in the space. Always
have a person stationed at the entrance to maintain
19-9
Student Notes:
