MTS Water Quality Guide - Manual (Page 19)

Heat Exchanger Care and Water Quality Guide Heat Exchanger Care 19
Mechanical cleaning
Complete the following steps if your internal inspection of the shell and tube heat
exchanger indicates that you need to remove any sediment or light scale from the
tubes:
1. Remove residues from the inside of the tubes with a rotary brush. Use a soft
nylon brush to prevent scratches in the metal surfaces since any scratches
will accelerate corrosion.
2. Flush the tubes with clean water to remove dirt and scale loosened during
the brushing.
3. Pressurize the shell side to verify the integrity of the tubes and all joints
before reassembling the heat exchanger.
4. Clean the bonnets as required, and reattach them to the heat exchanger. New
gaskets are required whenever you re-assemble the heat exchanger. Use of
oiled gaskets is acceptable.
5. Pressure test the tube side.
Chemical cleaning
Internal chemical cleaning of the tubes is required to remove calcium deposits
that build up in and around the tubes over time. Clean and flush the internal tubes
regularly.
1. Clean the internal water passage by flushing with a 15% solution of
inhibited muriatic acid (hydrochloric acid) in water. The length of time
required for flushing is dependent on the amount of scale built up in the
tubing. For 1 mm scale, flush the tubes for about 30 minutes. The system
must be open to vent gases as they become free.
2. Drain completely, then flush the tubes thoroughly with clean water.
3. Repeat the flushing with a neutralizing agent, such as a 5% sodium
carbonate solution, and drain completely. Flush with clean water.
4. Repeat the process in the opposite flow direction.
5. Remove any fluid residue with a commercial solvent.
For hydraulic fluid-to-
air heat exchangers
only
Depending on fouling conditions, MTS recommends inspecting your heat
exchanger every 500–2000 operating hours. If you notice a decrease in the
efficiency of your heat exchanger, it should be cleaned.
1. Clean all filters and screens.
2. Inspect the unit regularly for loose bolts and connections, rust, corrosion and
dirty or clogged heat transfer surfaces.
3. Remove dirt and dust from the heat transfer surface by brushing the fins and
tubes and blowing loose dirt off with an air hose or by turning on the fan. If
the surface is greasy, remove the motor and spray or brush the fins and tubes
with a mild alkaline solution or a nonflammable degreasing fluid. Follow
the degreasing with a hot water rinse and dry thoroughly. A steam hose may
also be used effectively.
4. Remove any dirt and grease from the casing, fan and motor. Sand and
repaint rusty or corroded surfaces.