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Heat Exchanger
Shellside scaling is typically the cause of any required maintenance. Descaling may be
chemical and in-place by circulating inhibited acid through the shellside. Operator should
contact a water treating chemical supplier for appropriate descaling procedures, agents
and apparatus.
1. Disassemble the exchanger
a. Disconnect blowdown piping.
b. Remove head bolts, head, pass divider and their gaskets.
c. Back off the bundle antivibration hold down bolts on the shell. Pull out the tube
bundle. Use a straight pull when removing the bundle – to avoid damaging the
longitudinal pass dividers.
2. If the shellside is severely scaled:
a. Loosen the bundle free by prying with
several bars inserted between tube sheet
and shell flange.
b. Use a block and tackle to pull bundle.
c. Pre-soak the shellside with inhibited
acid.
3. Reassemble in opposite fashion.
a. As the tube bundle is reinserted,
position the seals (of the
longitudinal pass divider) in the
upward direction (toward shellside
inlet) per diagram.
b. Typically, new gaskets are required for
reassembly.
c. Torque bolts hand tight in star fashion.
d. Insure alignment of head, pass divider and
shell flange and all gaskets.
e. Tighten again in star fashion.
f. Tighten head bolts first, then tighten bundle hold-down bolts ¼ turn past snug
Overhaul And Repair/General Cleaning
Normal cleaning includes removal of scale and rust from the proportional control valves
and the exchangers. The tubesides (blowdown water side) typically do not collect scale
or foreign matter. A fouled tubeside may be cleaned chemically (inhibited acid) or
mechanically with manual or rotary bristle brushes (take care not to damage U bends),
and with water flushing.
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Sentry Equipment Corp
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