Cooling Water Systems - Cooling Towers - Long Term Shutdown
September 18, 2002

Introduction

The long term shutdown of a cooling water tower involves measures to preserve the structure itself, electrical systems and mechanical components.  The tower will be exposed to extremes of the environment and unless these components are protected there may be problems when it comes to re-commission a cooling tower which can result in delays and unexpected costs.

Tower Structure

• Inspect the tower once a month with a complete and detailed inspection every six months.  The six month inspection should include checking all the fastening hardware and tightening of all loose bolts.

• For wooden structures, periodic wetting of the entire structure is required to prevent drying out of the wood and general deterioration.  More importantly a dry tower represents a considerable fire hazard.  Wood that has dried out will tend to shrink resulting in loosening of the joints.  Consideration should be given to a simple system for circulating water over the tower. 

• In colder climates, snow build-up on the fan deck must be monitored to avoid exceeding the load on the tower structure/deck.  Wet snow that has turned to ice represents a greater load on the structure and should be removed.

• In colder climates, snow will build-up in the fan stack area and on top of the drift eliminators.  These area should be monitored and excessive build-up of snow or ice should be removed if possible.

Mechanical Components

Mechanical components should be protected from internal moisture, rust and corrosion.  Consideration should be given to off-tower storage of mechanical components in a building to protect them from exposure to the outside environment.   Re-installation should be delayed as long as possible.  The following actions should be considered to protect mechanical components:

• Couplings should be sealed in heavy plastic with a suitable desiccant to control the humidity.

• Vibration switches should be sealed in heavy plastic with a suitable desiccant to control the humidity.

• Fans should be locked in place with rigid ties to the motor and gear support frame.  Ties should be easy to removed so that the fans can rotated every six months for a minimum of ten (10) revolutions.

• Gears should be filled completely to prevent the ingress of moisture.   The casing vent line (if provided) must be closed off.

• All shafts should be coated with a heavily grease to prevent rusting.

Electrical Components

• Electric motors should be sealed in heavy plastic with a suitable desiccant to control the humidity.

• Exposed motor shafts should be coated with a heavily grease to prevent rusting.