Page 188 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

170 Major Process Equipment Maintenance and Repair

Table 4-1
Fan Preventive Maintenance
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Fen Component Check For
Air Flow Obstructions, dirt, rags, etc. in inlet or outlet duct
work. Bird and protective screens and louvres
must be cleaned.
Housings, wheel and shaft All bolts tight? Wheel clean? Dirt can unbalance a
wheel. Cover bearings tightly with plastic film and
clean with steam, water jet, compressed air or
wire brush.
Cracks in wheel? Fan must be put out of service
until proper repairs are made.
Badly worn wheel blades, wear strips or blade
liners? In most cases, eroded areas can be repaired
by welding. Contact fan manufacturer for the
correct weld procedure for your wheel. Be sure to
electrically ground the wheel before welding to
avoid damaging the bearings. Be careful not to
contaminate welds from wheel coatings or
protective overlays. Repair all structural welds
with rod that meets original specifications. Grind
and repair all cracks.
Caution
After welding, balance should be checked. If it is
necessary to disassemble the wheel hub from the
shaft, see applicable section in operating manual.
Circulating oil lubricant Filter clean? Reservoir lzvel adequate?
systems
Alignment of fan bearings, Check alignment of fan bearings, flexible
flexible couplings. wheel and couplings, wheel and inlet bells regularly.
inlet bells Misalignment causes bearing or motor overheating,
wear to bearing dust seals, bearing failure and
unbalance.
V-belt drives Check belt wear, alignment of sheaves and belt
tension. Replace belts with a complete set of
matched belts, as new belts will not work properly
with used belts because of length differences. Belts
must be free of grease.
Dampers and VIV’s All linkage connections tight? Check all automatic
dampers for freedom of movement. Blades should
close tightly in closed position. Make adjustments
as required. Observe operating motors and controls
through a cycle. Clean dampers and VIV’s and
inspect for corrosion and erosion.
Surface Coatings Surface coatings or paints in good condition?
Repainting of exterior and interior parts of fans
and ducts extend the service life. Select paints to
withstand operating tempzratures. For normal