3.3 SYSTEM CLEAN OUT
Many boilers have been ruined with system
contaminants such as pipe dope, cutting oil,
metal shavings or chips and other debris which
are left in the piping. If these contaminants are
not removed, they will end up in the boiler.
SYSTEM CLEANING PROCEDURE
For steam systems, the boiler will need to be
connected to the header utilizing steam to purge
the piping and thus push the debris out of the
system. However, at this time all condensate
must be wasted until it runs clear and water
analysis of the condensate indicates that it is free
of contaminants. Steam trap strainers must be
periodically opened and cleaned of any debris
which accumulates.
During this system clean out, the boiler make-up
water must be properly softened and treated. At
the conclusion of the system clean out, the
condensate must be reconnected.
For old or existing steam systems, the installation
process may have jarred debris loose. Following
the boil out of the new boiler, the condensate
should be wasted until it is within proper
guidelines. Check all steam trap strainers to
assure their cleanliness. Refer to the succeeding
section on replacement boiler installations.
3.4 REPLACEMENT BOILER INSTALLATIONS:
PROTECTION AGAINST CORROSION & SEDIMENT
BOILER MUST CONTROL FEED WATER
The water feed to the boiler must be controlled by
the boiler-mounted water level control. It is
unacceptable to use gravity return or to let the
water feed be controlled by a condensate/
receiver/ condensate pump system. The water
feed to the boiler must be controlled:
by a feed pump control which is mounted on
the boiler. This control is to activate the feed
pump on a boiler feed system. It will be
necessary to supply such a system if not already
installed. - OR -
by an automatic water feeder mounted on the
boiler. This is used only on systems requiring
100% make-up, such as humidification, steam
process, etc.
NOTE
It is not recommended to provide the make-up for
a closed steam heating system to the boiler by
means of a water feeder. It is preferred that
system make-up be connected to the condensate
return tank of a boiler feed system.
A boiler feed system may be used in conjunction
with an existing condensate receiver system by
allowing the receiver system to pump condensate
into the boiler feed system tank.
CLEAN OR REPLACE ALL SYSTEM PIPING
AND HEATING UNITS
Arrange for chemical and mechanical cleaning of
the entire system. A chemical treatment company
should be consulted for the proper means of this
chemical cleaning.
Replace any piping considered to be deteriorated
beyond safe or cleanable condition. Flush the
system clean, being certain to isolate the boiler.
DO NOT FLUSH THE SYSTEM THROUGH THE
BOILER
NOTE: For some old systems, there is a
reluctance to clean the piping because of the
possibility of leaks occurring in badly corroded
lines. Should the customer refuse cleaning, it is
necessary to install filtration equipment. Install
either a fibrous filter or a centrifugal filter in the
boiler return piping. This will collect and remove
sediment from the system. A booster pump may
have to be installed as well to overcome the
additional pressure drop introduced in the line by
the filter. When filling the system, provide
chemical treatment as outlined in Section 3.5.
CAUTION
Failure to properly clean the system or to install
mechanical sediment removal equipment can
result in tube blockage and severe corrosion plus
damage to pumps, controls, and air removal
device.
Summary of Contents for Forced Draft Steam Boilers
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