remove the gauge for calibration, unless an onsite
calibration team can perform the adjustments
stream. The WHB is positioned so it can effectively
with the instrument in place.
capture the hot exhaust gases from the turbine before
they are exhausted from the ship.
Safety Valves. These valves are routinely
On the CG-47, DD-963, and DDG-993 class
inspected during normal boiler operation. They should
ships, there are two different styles of WHBs. One is
also be periodically tested according to the PMS. During
a horizontal straight tube style manufactured by
these tests, you should check for proper lifting and
Combustion Engineering (CE). The other style,
reseating pressures. Periodically, these safety valves
manufactured by Conseco, has a horizontal coiled
must be removed so they can be bench tested according
tube bundle. Even though these boilers are different
to the PMS and the requirements in NSTM, chapter 221,
in design, they serve the same purpose-to generate
or if they fail the installed PMS tests.
steam for cooking, laundry services, and heating the
water, FO, and LO. These boilers also function
Pilot Operated Valves. Tests and inspections
according to the same principles, with only small
performed on these valves should be handled in the same
differences in their operating parameters. Since the
manner as those for the valves described earlier in this
design differences are minimal, and a complete
chapter.
description can be found in each unit's applicable
propulsion plant manual, we will only discuss the
Steam Drum. The steam drum is primarily a
differences.
reservoir and is usually only inspected in conjunction
The first and probably the most obvious
with a boiler inspection.
difference is in the design of the steam generating unit
(boiler). The CE boiler is square and has straight
Deaerating Feed Tank. The DFT is similar to the
tubes. The Conseco boiler is round and has coiled
separator in that it serves as a reservoir, but that is the
tubes. The second design difference is that the CE
only similarity. When the DFT is in normal operation,
boiler system uses a deaerating feed tank (DFT) to
you should test its ability to remove dissolved oxygen
remove excess oxygen from the water. The last
within 2 hours after start-up and daily thereafter.
difference is not as obvious as the others. The steam
There are also some internal components that will
drum (separator) has steam connections installed to
periodically require maintenance according to the
enable the operator to perform a surface blow. Surface
PMS or as a result of an unsatisfactory dissolved
blowing is an additional method commonly used on
oxygen test.
propulsion steam plants to maintain proper water
chemistry limits.
Boiler. The boiler should be tested continuously
while it is in operation. Inspections, however, should be
TESTS, INSPECTIONS, AND FUNCTIONAL
accomplished periodically according to the PMS;
CHECKS. All steam system tests, inspections, and
NSTM, chapters 220, Vol. 2 and 221; and any other
functional checks are either covered in the PMS or in
applicable NAVSEA technical directive. These
inspections are normally driven by the number of boiler
the EOSS. Some of the equipment items on which you
will perform tests, inspections, or functional checks are
operating hours and performance.
briefly discussed in the following paragraphs.
TROUBLESHOOTING. The two most common
Boiler Control Panel. The tests or inspections
problems you will encounter with the WHB steam
associated with this piece of equipment are usually
system are (1) maintaining the proper steam pressure
conducted before the boiler is placed in operation. When
and (2) maintaining the proper steam drum water level.
The most frequent of these problems will be maintaining
performing the preoperational EOSS procedure
(WHBP), check all of the indicating lamps and alarms
a proper water level.
for proper operation.
Maintaining the Proper Water Level.
Maintaining the proper water level is very crucial.
Water Level Controller. Most tests or inspections
Failure to maintain the proper water level can lead
performed on this equipment are accomplished
to some very serious problems. When this problem
during boiler operations. The best time to pinpoint
occurs, a quick diagnosis is needed to restore the water
a problem is during normal operations. There is a
level to normal before the boiler tubes run dry. The
specified time, however, when you will need to
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