in figure 3-23. Units of this type normally consist of a
receiver or condensate tank and pump independently
controlled by float switches. A check valve and a vent
on the receiver allow the receiver to fill and empty as the
Condensate return pumps are maintained as
prescribed by the manufacturer of the unit. Usually, the
motor should be oiled, the check valves and vents
cleaned, the float switches adjusted, the pump repacked,
and the tank cleaned at least once each year.
Expansion joints and expansion loops in long
heating lines are convenient devices for handling the
pipe elongation caused by expansion. The five major
types of expansion joints are as follows: slip joint,
bellows joint, swing joint, expansion loop, and ball
The slip joint is shown in figure 3-24. The female
part of the joint is placed over the male part and the joint
is held tight by the packing that permits expansion. The
kind of packing used determines the temperature to
which the joint can be subjected.
The bellows joint, as shown in figure 3-25, has a
metal bellows that flexes as expansion occurs. The joint
Figure 3-23.A typical condensate return pump.
Figure 3-24.-A typical slip-type expansion joint.
consists of a thin-walled corrugated copper stainless
steel tube clamped between flanges. Rings help to keep
Figure 3-25.A typical bellows-type expansion joint.
the corrugations under relatively high pressure. The
steam pipe and joint should be supported and guided to
keep misalignment to a minimum.
The swing, or swivel, joint is most often used to
allow expansion to occur naturally in a system that has
screwed joints. When it is used with welded elbows, the
swing joint introduces torsional strains in the elbows
and in the swing piece.
The expansion loop absorbs expansion through the
formation of U- or Z-loops in the pipeline.
The ball joint is often used instead of the expansion
loop, because it requires less space and material. A ball
joint consists of four basic parts. The joint has a casing
or body to hold the gaskets and a ball. The ball is a
hollow fitting shaped externally like a ball at one end
(inside the casing) and is threaded, flanged, or adapted
for welding to the pipe at the other end. There are two
gaskets that hold the ball and provide the seat. There is
also a retaining nut or flange that holds the ball and
gaskets in the casing. The end of the two pipes being
coupled is connected to the joint casing; the end of the
other pipe is connected to the ball. In operation, the ball
joint allows the movement of the pipe with 30° to 40° of
flexibility, plus a rotating or swivel motion of 360°.
The slip-type joint must be kept properly aligned,
adequately packed, within the proper limit of travel, and
thoroughly cleaned and lubricated. You should adjust
or replace the packing, as required, to prevent leaks and