defective gaskets, bellows, valves, valve seats, floats,
buckets, linkages, and orifices. Use only matched sets
of replacement valves and seats. Make certain all
replacement parts are of the correct size. Do not change
the weight of floats or buckets when repairing traps, or
operation may be affected. Often, it is more
economical to purchase and install new parts than to
recondition defective elements. Repair or replace
leaking bypass valves. Repack valve stems.
header and one on the plate). Be sure you remove all
the corrosion or other surface deposits and all adhering
pieces of the old gasket. It is impossible to obtain a
tight joint as long as any foreign matter remains on
either seating surface or in the corners of the fitting. Be
sure to water-soak the new gasket for 24 hours before
The forced-draft fan should be checked daily to
prevent an accumulation of dust in or around the fan.
KEEP THE FAN CLEAN! Also, check daily on the
sound of the fan. If it is not normal, report the matter
promptly to your supervisor.
A daily check should also be made to ensure
adequate lubrication of the fan. The temperature is
another item that should not be overlooked. This you
can test by feel. In case of excessive temperature,
notify your supervisor immediately.
Because induced-draft fans are exposed to hot,
dirty gases, they must be observed closely to prevent
operating difficulty. Taking proper care of the fan
requires DAILY attention to ensure that the following
conditions are met:
1. Bearings are kept cool and well lubricated.
2. Fan is kept clean. Also, see that any change from
the normal in sound is reported promptly to your
HANDHOLE AND MANHOLE GASKET
At each regular boiler overhaul, all handhole and
manhole fittings and gasket seating surfaces on the
drums and headers must be cleaned, inspected,
repaired, or renewed if necessary. If the plates are
warped, distorted, or otherwise damaged, they must be
repaired or renewed.
Whenever handholes and manholes are opened,
new gaskets must be fitted. After a gasket has once
been compressed, it must be discarded, as it will not
provide a seal. Be sure to use the correct size and type
of gasket. Never use any makeup compound on the
seating surfaces when installing the gaskets. Graphite
may be used on the threads of the stud to prevent
seizure of the nut.
Power-driven wire brushes are best for cleaning
the seating surfaces. Scrapers should be used only
when wire brushes are not enough to clean the surface.
Scrapers must be used with great care, if they are used
at all, since they tend to remove too much metal from
the seating surfaces.
If the gasket seating surfaces show a lot of pitting,
you may have to get these surfaces machined or
reground. If the seating surface on a handhole or
manhole plate is badly pitted or damaged, discard the
plate and replace it with a new one or one that has been
machined to blueprint specifications.
The clearance between the shoulder of a manhole
plate and the manhole must not exceed one-sixteenth of
an inch when the plate is centered accurately. Figure 2-6
shows where the clearance is measured. If the clearance
is greater than one-sixteenth of an inch, the plate should
be built up by electric welding at the inner edge of the
shoulder. Steelworkers should do the welding, so the
manhole plate may be stress-relieved after it is welded
and the welded surface may be remachined.
To position a manhole gasket properly, fit it on the
long axis until the inner edge of the gasket fits the
shoulder snugly at the ends of the long axis of the
manhole plate. The clearance between the gasket and
the shoulder should be equalized at the top and bottom
of the short axis. Do NOT allow the outer edge of the
gasket to protrude at any point beyond the
gasket-seating surface in the drumhead. If an edge
protrudes, the gasket may unravel when it is
compressed by the tightening of the manhole cover.
Discard any gasket that protrudes beyond the edge of
the gasket-seating surface.
Before installing a new gasket, thoroughly clean
two gasket seating surfaces (one on the drum or
Figure 2-6.Manhole plate clearance.