Figure 2-3.Low water plate.
additional feedwater treatment that might not
otherwise be necessary. Since the boiler and system
arrangements usually make it impractical to perform
daily and monthly maintenance of the low water cutoff
devices, it is essential to remove the operating
mechanism from the bowl annually, or more
frequently if possible, to check and clean the float ball,
the internal moving parts, and the bowl housing. Also,
check the cross-connecting piping to make certain that
it is clean and free of obstructions.
GAUGE GLASS REPLACEMENT
A broken or discolored gauge glass should be
replaced at once. Always use new gaskets when
replacing a gauge glass. Use the proper size rubber
packing. Do not use "loose packing" that could be
forced below the glass and possibly plug the valve
Close the valves when replacing the glass. Slip a
packing nut, a packing washer, and a packing ring onto
each end of the glass. Insert one end of the glass into the
upper gauge valve body far enough to allow the lower
end to be dropped into the lower body. Slide the
packing nuts onto each valve and tighten.
If the glass is replaced while the boiler is in service,
open the blowdown valve and slowly bring the glass to
operating temperature by cracking the gauge valves
slightly. After the glass is warmed up, close the
blowdown valve and open the gauge valves
completely. Check the try cocks and gauge cocks for
freedom of operation and clean them as required. It is
imperative for the gauge cocks to be mounted in exact
alignment. If they are not, the glass will be strained and
may fail prematurely.
Proper control of the water level requires that the
feedwater regulator be maintained. Here are a few
pointers for regulators.
If the water level changes from its normal position,
make sure you adjust the bypass to manual operation
and check promptly for the source failure. If leaks
develop around the packed stems, see that they are
stopped immediately. If the boiler is off line, close the
hand valve in the feed line. Bear in mind that the
regulator is not designed for use as a stop valve. About
once every 3 months, you will probably be called on to
assist in blowing down the steam and water
Valves deserve special care and attention if they
are to work as intended. There may be variations
among activities in the type and frequency of valve
inspection and servicing requirements. Therefore,
follow instructions issued by your activity when they
differ from those outlined here.
Types of valves that you may be responsible for
helping service and maintain at regular intervals
include (1) stop valves of the globe or gate type and (2)
stop-and-check valves, which combine in one tray and
angle or stop valve of the globe type and a check valve.
At least once every 3 months, valves that have not been
operated for some time should be operated to prevent
sticking. Make sure that you also check for leaks, bent
stems, a missing or broken handle, and lubricate the
exposed threads and gearing of the valve stem.
Loosen and lift the packing follower about once
every 3 months or more often if possible. Lubricate the
packing with graphite bearing oil or graphite bearing
grease. Replace the packing followers and tighten
sufficiently to ensure against leaks.
BLOWOFF or BLOWDOWN VALVES should
be opened at least once a day. There are four reasons
for using these valves:
1. Controlling high water
2. Removing sludge and sediment
3. Controlling chemical concentrations in the
4. Dumping a boiler for cleaning or inspection
The amount and frequency of blowing down
depends on a chemical analysis of the water in the
boiler and operating conditions.
On a quarterly basis, inspect the blowoff valves
when the boiler is washed out and an internal
inspection is made. Check the valves for leaks, and
inspect the pipe and fittings between the blowoff