Maintenance and Inspection - Cooling Towers
September 10, 2003
Introduction
The following inspection checklist provides a
general guide of what to look for when performing a cooling tower inspection.
The checklist is general in nature so some of the points may not apply to your
particular installation.
The results from a thorough cooling tower
inspection will enable the plant to properly plan repairs and maintenance.
A properly maintained cooling tower will provide trouble free and reliable
operation.
Maintenance and Inspection Schedule
Daily |
-
Check operation of cooling water pumps for excessive noise, vibration,
etc.
|
Weekly |
-
Inspect trash screen and remove accumulated debris
|
Shutdown |
-
Perform a detailed inspection of system.
|
Inspection Checklist
Tower Casing |
- Check for leaks, holes, cracks or general
deterioration in the structure.
- Make sure access doors are in good working
condition and that doors shut tightly when tower is in operation.
- Check steel casing for corrosion or scale
build-up.
- Check wood casing for signs of decay, soft
rot or plywood delamination.
- Check Fiberglass for evidence of brittleness
or cracking.
|
Structure |
- Steel Structures
Inspect steel structures for corrosion, particularly loss of
metal.
Spot check the tightness of bolted joints.
Check for corrosion near welded joints on galvanized steel
towers.
- Wood Structures
Inspect wood structures for wood decay, cracks, fractures and rot
in wood members.
Perform both visually and by tapping with a hammer. A dull,
low-pitch sound indicates softness, while a higher pitch sharp sound
indicates sound wood. Probe soft spots with a sharp object to determine
the extent of the damage. Pay particular attention to the wood around
fasteners as well as the bottom of columns.
- Fiberglass or Plastic Structures
Inspect fiberglass or plastic structures lloking for evidence of
tearing of cracking. Spot check the tightness of bolted joints.
|
Fan Deck |
- Check the general condition of the fan deck
material looking for leaks, holes, cracks or general deterioration in the
structure.
- Check for the presence of tripping hazards.
|
Cooling Tower
Access |
- Stairs
Check for evidence of wood decay or steel corrosion.
Check for loose treads, handrails or stringers.
Check that all hardware is in good condition and tight.
- Ladders
Check the general condition of the material.
Check that all hardware is in good condition and all connections
between the tower and ladder are secure.
- Walkways
Check the general condition of the material.
Check for loose treads or handrails.
Check that all hardware is in good condition and tight.
Particular attention should be paid to any damage or
deterioration that may pose a potential hazard to personnel.
|
Cold Water
Basin |
- Check for excessive build-up of sludge or
debris. Clean as required.
- Check condition of sump, sump screen. Clean
as required.
- Check the general condition of the basin
material.
- Check for any signs of leaks or breakdown of
sealing material.
|
Distribution
Basins |
- Check the general condition of the material.
- Check for leaks.
- Check that all hardware is in good condition
and tight.
|
Piping |
- Examine all supports.
- Check for leaks at all connections.
- Check the general condition of all piping
looking for signs of corrosion or deterioration.
|
Spray Nozzles |
- Check for missing or damage.
- Check for clogged or blocked nozzles.
- Check that all nozzle components are in
place and working properly (i.e. splash plates).
|
Tower Fill |
- Splash Fill
Check the condition of the splash bars. Check for sagging,
broken, missing, heavily-scaled pieces.
Check the support grids.
Check the support members for deterioration and damage.
- Film Fill
Check for build-up of scale, algae or other contaminants on the
surface of the fill.
Check for damaged sheets or sections.
Check the support members for deterioration and damage.
|
Drift
Eliminators |
- Check for cleanliness and that all air
passages are clear.
- Check the condition of the seals to assure
that water can't bypass the drift eliminators.
|
Louvers |
- Make sure all louvers are in place.
- Check for excessive scale build-up or
biological growth.
- Check the condition of the support members.
|
Mechanical
Systems |
- Gear Boxes
Check the oil level and condition. Drain off a small sample and
check it for water, metal shavings or sludge. Add or replace the oil as
required.
Check for oil leaks and replace seals as required.
Check the backlash and endplay in the gear and record values for
future reference.
Check the mounting of the gear box to ensure it is tight and in
good condition.
- Couplings and Drive Shafts
Check the coupling alignment.
Check the mid-span bearing (if so equipped) and lubricate are
specified in manufacturer's instructions.
Check the drive shaft for corrosion or damage.
- Belt Drives
Check the condition of the pulleys noting any corrosion
or loss of metal.
Check for proper belt tension and alignment.
Check the condition of the belts. If the belt shows signs of
wear, gouges or cracks they should be replaced.
Check the fan shaft bearings for proper lubrication, tightness
and that the seals are in good condition.
Check the support structure for corrosion or damage.
|
Fans |
- Check fan blades for corrosion or erosion.
- Check for excessive build-up of deposits.
- Check the connection between the blades and
the hub.
- On fans with variable-pitch blades,
carefully measure the pitch angle of each blade and re-adjust to the
manufacturer's recommendations if required.
- Operate the fan and check for excessive
vibration that may indicate an out of balance condition.
|
Fan Stacks |
- Check the condition of the material.
- Check that all hardware is in good condition
and tight.
- Check for leaks or holes.
- Measure the fan blades tip clearance all
around the stack using the longest fan blade. Adjust tip clearance as per
the manufacturer's instructions if required.
|
The condition of the cooling tower is important
not only from the performance point of view but also from a health point of
view. Cooling towers are ideal breeding grounds for water born bacterial,
such as Legionella bacteria. Cleanliness of all parts of the tower will
minimize the chance of these bacteria growing in the cooling water system