Bell & Gossett HT 202A SM Models CHXS Fixed Tube Sheet Heat Exchangers - Manual (Page 3)

5. Do not blow out heat exchangers with air when operating
fluids are of a flammable or otherwise hazardous nature.
WARNING: Proper precautions must be taken (special
clothing, equipment, etc.) to protect personnel from
injury due to escaping fluids.
6. Provide convenient means for frequently cleaning heat
exchangers as suggested below:
a. Circulating hot wash oil or light distillate through tubes or
shell at good velocity will effectually remove sludge or
other similar soft deposits.
b. Soft salt deposits may be washed out by circulating hot
fresh water.
c. Some cleaning compounds on the market, such as
“Oakite” may be used to advantage for removing sludge or
coke, provided hot wash oil or water, as described above,
does not give satisfactory results.
d. If none of the above described methods are effective for
the removal of hard scale or coke a mechanical means
may be used. The interior of the tubes may be rodded.
e. The exterior or shell side of the tubes of a fixed sheet heat
exchanger can only be cleaned chemically by using a
chemical dissolved in water solution. We suggest that the
user contact the manufacturer of the cleaning chemical for
instructions.
WARNING: Care must be exercised when handling
certain fluids. Follow manufacturers instructions. Use
eye and skin protection. Wear a respirator when required.
3. In shutting down, flow of hot medium should be shut off first.
If it is necessary to stop circulation of cooling medium the cir-
culation of hot medium should also be stopped by by-passing
or otherwise.
4. Do not operate equipment under conditions in excess of those
specified on nameplate.
WARNING: Failure to operate the heat exchanger
within the design pressure and temperature on the
nameplate may result in damage to the heat exchanger and
potential injury to adjacent personnel.
5. Drain all fluids when shutting down to eliminate possibility of
freezing and corrosion. To guard against water hammer, con-
densate should be drained from steam heaters and similar
apparatus both when starting up and when shutting down.
6. In all installations there should be no pulsation of fluids since
this causes vibration and strain with resulting leaks.
7. All gasketed joints should be checked after starting for leaks
and tightened if necessary.
WARNING: The CHX and CHXS exchangers are suit
able for use as heaters using steam as the heating
medium. These exchangers are, however, fixed tubesheet
units and, therefore, not designed to absorb thermal shock
inherent in the intermittant service of on and off heating
with frequent short intervals of demand. Their recom-
mended use is where service is continuous or steady, with
relatively long periods between shutdown and start-up.
Heat exchanger failure due to thermal shock may result in
potential personal injury.
MAINTENANCE
1. Do not open heads until all pressure is off equipment and the
unit is drained.
2. Remove the bonnets. Inspect all tubes carefully for possible
erosion, corrosion, or foreign material.
3. Inspect all anodes to be sure they are neither excessively cor-
roded nor insulated with scale. Scrape to a bright surface.
4. Inspect filters in the system to prevent foreign matter from
entering the exchanger.
3
7. When replacing heads, use a torque wrench.* Tighten 1 /
4
"
diameter bolts (2” diameter units) to 6 ft-lbs., 5 /
16
" diameter
bolts (3" & 4" diameter units) to 16 ft-lbs., and 3 /
8
" diameter
bolts (5", 6", & 8" diameter units) to 24 ft-lbs. If the gasket joint
still leaks, tighten in 2 ft-lb. increments until leak stops.
*The above torque values apply to well lubricated nut bearing
* surfaces.