WATER TANK FAILURES
Where a plumbing system has been in use for some
time, two failures in water tanks are (1) leaky seams
and (2) corroded areas requiring welded patch plates.
To repair a defective seam, first drain the water tank
dry. Then clean the surfaces to be repaired until they
are right. By welding or brazing, you can then make the
leaky portions watertight.
As an effective tank patch for a large hole, you
need both a temporary and a permanent patch. One
temporary patch is a tapered softwood plug. Insert the
plug in the hole, and tap it lightly with a hammer until
the seal is watertight. Then saw off the top of the plug,
so it is flush with the tank wall.
Next, the area around the plug to be covered by the
permanent patch should be cleaned by wire brushing.
Drain the tank; now you are ready to apply the
permanent patch. One type of permanent patch
includes a rubber gasket and a metal plate. Rubber
sheeting, at least 6 inches by 6 inches and l/16 inch
thick, may be used for the gasket, and it should be
centered on the plug and cemented with adhesive. The
patch plate of black steel or nonferrous (no iron) metal
should be of the same material and thickness as the
tank wall but a lot larger than the hole. Cover the hole
with the metal plate, keeping an equal overlap around
the edges, and braze or weld the plate to the tank, using
a continuous seam.
Q11. What is the most common reason a threaded pipe
joint will leak?
Q12. Water tank failures normally occur due to what
LEARNING OBJECTIVE: Understand
operation, maintenance, and repair of water
closet flush tanks.
Moisture on the floor at the base of a water closet
bowl usually means the seal or gasket between the
closet and its outlet has failed; however, it can result
from condensation on the tank or piping or from
leakage of the tank, flush valve, or piping. When the
seal leaks, remove the water closet bowl and install a
new seal to prevent damage to the building. This also
prevents entry of sewer gas into the room.
In servicing plumbing fixtures, you have the job of
clearing stoppages in water closets. Information on
tools and chemicals used in clearing stoppages in water
closets and other fixtures is given later in this chapter.
Knowing the principles of operation of a flush tank
will enable you to find the source of trouble when a
flush-type water closet tank is not operating properly.
For clarity, all of the parts of a flush tank have been
labeled in figure 5-41. Keep in mind that in different
types of flush tanks you may find some change in the
method of operation.
Table 5-4 explains the principle operation of a
water closet flush tank. Simple though it may seem,
you must understand the operation to troubleshoot an
inoperative flush tank.
FLUSH TANK REPAIRS
When water continues to run into the closet bowl
after the flush tank is full, the trouble is in some part of
the inlet valve assembly (ball cock assembly) or the
stopper valve is not seated. The plunger has failed to
close the inlet valve as it should, and thus the excess
water that continues to flow in (after the tank has
reached the proper level) is being discharged through
the overflow pipe and into the bowl.
In checking for the source of trouble, several
defects to look for are a leak in the float ball, a bent
float arm, a worn washer on the bottom of the plunger,
Figure 5-41.Water closet flush tank.