Specifications

52
SERVICE
Servicing Coolers and Condensers —
When cool-
er heads and partition plates are removed, tube sheets are
exposed showing the ends of tubes. The 30GXN,GXR,HX
units use a flooded cooler design. Water flows inside the tubes.
TUBE PLUGGING — A leaky tube in one circuit can be
plugged until retubing can be done. The number of tubes
plugged determines how soon the cooler must be retubed. All
tubes in the 30GXN,R and 30HX coolers and 30HX condens-
ers can be removed. Loss of unit capacity and efficiency as
well as increased pump power will result from plugging tubes.
Failed tubes should be replaced as soon as possible. Up to 10%
of the total number of tubes can be plugged before retubing is
necessary. Figure 24 shows an Elliott tube plug and a cross-
sectional view of a plug in place. The same components for
plugging and rolling tubes can be used for all coolers and
30HXC condensers. See Table 34. If tube failure is in both
circuits, using tube plugs will not correct problem. Contact
your Carrier representative for assistance.
RETUBING (See Table 35) — When retubing is to be done,
obtain service of qualified personnel experienced in boiler
maintenance and repair. Most standard procedures can be
followed when retubing the 30GXN,R and 30HX heat
exchangers. Care must be taken as the tubes are rolled in the
center tube sheet and require special pulling tools. A 7% crush
is recommended when rolling replacement tubes into the
tubesheet. A 7% crush can be achieved by setting the torque on
the gun at 48 to 50 in.-lb (5.4 to 5.6 N-m).
The following Elliott Co. tube rolling tools are required:
113123 Expander Assembly 213123 Mandrel
2134123 Cage 2115122 Rolls
Place one drop of Loctite No. 675 or equivalent on top of
tube prior to rolling. This material is intended to “wick” into
the area of the tube that is not rolled into the tube sheet, and
prevent fluid from accumulating between the tube and the tube
sheet. New tubes must also be rolled into the center tube sheet
to prevent circuit-to-circuit refrigerant leakage.
Table 34 — Plugging Components
*Order directly from: Elliott Tube Company, Dayton, Ohio.
†Measure tube ID before ordering.
**Can be obtained locally.
Table 35 — Tube Diameters
NOTE: Tubes replaced along heat exchanger head partitions must
be flush with tube sheet.
TIGHTENING COOLER/CONDENSER HEAD BOLTS
O-Ring Preparation
— When reassembling cooler and con-
denser heads, always check the condition of the O-ring(s) first.
The O-ring should be replaced if there are any visible signs of
deterioration, cuts or damage. Apply a thin film of grease to the
O-ring before installation. This will aid in holding the O-ring
into the groove while the head is installed. Torque all bolts
to the following specification and in the sequence shown in
Fig. 25.
3
/
4
-in. Diameter Perimeter and
Plate Bolts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 to 225 ft-lb
(271 to 305 N-m)
1. Install all bolts finger tight.
2. Follow numbered sequence shown for head type being
installed. This will apply even pressure to the O-ring.
3. Apply torque in one-third steps until required torque is
reached. Load all bolts to each one-third step before
proceeding to the next one-third step.
4. No less than one hour later, retighten all bolts to required
torque values.
5. Restore water/brine flow and check for leaks. Fix leaks as
necessary. Replace insulation (on cooler heads only).
Inspecting/Cleaning Heat Exchangers
COOLERS — Inspect and clean the cooler tubes at the end of
the first operating season. Because these tubes have internal
ridges, a rotary-type tube cleaning system is necessary to fully
clean the tubes. Tube condition in the cooler will determine the
scheduled frequency for cleaning, and will indicate whether
water treatment is adequate in the chilled water/brine circuit.
Inspect the entering and leaving thermistors for signs of corro-
sion or scale. Replace the sensor if corroded or remove any
scale if found.
Use extreme care when installing plugs to prevent damage
to the tube sheet section between the holes.
COMPONENTS FOR PLUGGING PART NUMBER
For Tubes
Brass Pin 853103-1*
Brass Ring 853002-640* or -657†
For Holes without Tubes
Brass Pin 853103-1A*
Brass Ring 853002-738*
Roller Extension S82-112/11
Loctite No. 675**
Locquic “N”**
ITEM INCHES MILLIMETERS
Tube sheet hole diameter: 0.756 19.20
Tube OD 0.750 19.05
Tube ID after rolling: 0.650 16.51
(includes expansion to to
due to clearance) 0.667 16.94
PIN AND RING INSTALLED
TUBE SHEET
PIN
TUBE
RING
PIN
RING
Fig. 24 — Tube Plugging