whenever possible. In the following paragraphs, we will
CAUTION
discuss some tips concerning component repairs that
should save your ship money and your equipment
Use of an inappropriate solvent can cause
downtime.
damage to the components of the valve.
Automatic Control Valves. Automatic control
For these reasons, you should always follow an
valves are very versatile and, if properly maintained,
approved materials listing on the PMS card or in the
they will provide long periods of service before
manufacturer's technical manual.
complete replacement is necessary. The air-operated
type of valve, however, will require more repair
Automatic Control Valves. The cleaning and
attention than the other valve types.
lubrication of automatic control valves and their
actuators is vital to the proper operation of every system
Air-operated valves use a rubber diaphragm and
in the engineering plant. Electric solenoid valves and the
stem collar seal to operate. These rubber components
self-contained LO unloader valves we have already
have a much higher failure rate than the valves that
described are the only automatic control valves that will
operate without them. The main factor that causes
require cleaning but not lubrication. All the other types
diaphragm failure is the system in which the valve is
will require continuous care involving both cleaning and
installed. For example, the rubber diaphragm in a steam
lubrication.
system valve will have a much higher failure rate than
one on an LO system valve. Heat transfer from the
You must pay very close attention to the control
system piping through the valve body is one of the
valve and actuator stem area. The stem and surrounding
primary factors that will contribute to the diaphragm's
area is where most of the dirt will collect. If the packing
failure. Another factor is the amount of moisture and
gland has any leakage, corrosion will start in that area.
foreign material (rust) in the air supplied by the ship's
Valve Operator Mechanical Linkages. Proper
service air system. Over a period of time, any moisture
cleaning and lubrication of valve operator mechanical
in the air system can cause the diaphragm to rot.
linkages is very important to maintain ease of operation.
Moisture in the air system will also cause rust to form
These mechanisms are designed to be helpful and
in the piping. Eventually, the rust particles will flake off
timesaving because they allow you to operate valves that
and be carried downstream to the diaphragm area,
are located in hard-to-reach places. Remember, if you
causing wear and holes in the rubber.
want to avoid waking three compartments over and five
decks down, you must properly maintain these
As maintenance goes, these rubber components are
operators.
inexpensive and easy to replace. When replacing the
stem collar seal, you must remember to treat it in the
The rod or rigid type of operators with universal
same way as you would a bicycle tube. The seal is
joints and gear cases will require more attention than the
delicate and can be easily damaged or punctured. To
flexible cable operators. This is because the universal
avoid damage to the seal, you must clean the housing
joints in the rod-type operators are not enclosed and are
thoroughly and make sure it is free of abrasives. You
constantly exposed to the environment. Being exposed,
must also be careful during assembly to avoid pinching
these valves will require more frequent cleanings. After
the seal between the metal surfaces.
cleaning, you must also apply a fresh coat of lubricant.
To maintain the gear cases, you should periodically open
Your ability to make shipboard repairs to the valve
them (if a cover is provided), remove the old grease,
body will also be a time-saver. You can perform minor
clean them, and repack them with new grease.
repairs, such as repacking and lapping the valve disk and
seat, with minimal effort. Occasionally, however,
The flexible cable valves are similar to a
according to the PMS or because of component failure,
speedometer cable in design, except each end of the
you will have to remove the valve and have it delivered
cable has a bearing installed. Each bearing housing is
to an IMA for an overhaul.
fitted with a grease fitting, so you can use a grease gun
to provide lubrication.
In the case of the air pilot controllers, all repairs will
have to be performed by an IMA. Sometimes the larger
OVERHAUL, REPAIR, AND REPLACEMENT
IMAs will maintain a pool of controllers. If this is the
OF COMPONENTS. Depending on the age of the
equipment and the availability of parts, it is usually more
case, you need only to send a faulty air pilot controller
in and pickup an already reconditioned unit that is ready
cost effective to overhaul or repair the equipment rather
for installation.
than replace it. Try to avoid complete replacement
