This HVAC method Statement covers the Installation of Cooling Towers in line with project requirements, as indicated in the approved shop drawings, specifications and manufacturer’s instructions.
All the materials received at site shall be strictly as per the approved technical material submittal for cooling towers. Shall be inspected upon receipt & approved by the engineer prior to proceeding with the installations. Any discrepancies or damages found shall be reported to the supplier for rectification or replacement as applicable.
Any rejected material shall be removed from site immediately.
All construction preliminary inspection/testing works shall be carried out in accordance with the specifications, manufacturer recommendations and to be done by qualified Mechanical Engineers and shall be checked and approved by MEP Subcontractor Construction Manager along with QA/QC Engineer.
At the end all installation activities to be approved by the consultant.
HSE Requirements
All site safety rules & regulations shall be complied.
Supervisors will deliver tool box talks, relevant to these activities to all operatives involved in the installation and shall be recorded.
All operatives will be equipped with minimum personnel protective equipment; hard hat, coveralls, safety boots, safety glasses.
The persons using cleaning fluid, solvent cement & any other forms of chemicals have to wear hand gloves.
Ensure competent, experienced & trained personnel shall install the cooling tower / equipment.
During installation, display warning sign boards and barricade the area whenever necessary, close monitoring by the site engineers during cooling tower installation is highly recommended.
Ensure that all operatives fully understand the requirements of this method statement and applicable manufacturer instructions.
Necessary Tools & Equipment
Following tools shall be arranged before starting the cooling tower installation activities:
- Tool Box
- Lifting/ Rigging Equipments
- Basic Electrical Tools
- Electric Drill Machine
- Step Ladders
- Long Cables/ Guide Rope
- Welding/ Brazing Machine (if required)
- Torque Wrench
- Pipe Cutting Machine
- Grinding Machine
- Pressure Gauge
- Mobile Scaffolds
- Staging Platforms
Material Transport/ Delivery
Cooling Towers are factory assembled to assure uniform quality and minimum field assembly, special care must be taken to ensure that units are offloaded from containers without any damage, rough handling can result in damage to the unit.
Use appropriate type of vehicles in transporting the units and make sure these are protected against any mechanical & weather damage.
As soon as the units arrive at site, raise immediate inspection to the consultant & inspect thoroughly for damage, hence, in case of transit damage, supplier/ manufacturer must be informed immediately.
Ensure that the units have been inspected & accepted by the consultant as per the approved material submittal prior to site storage.
Storage on Site Store
Ensure that the storage location of the cooling tower are clean, dry and free from any mechanical and operational activities that may cause damage.
It is recommended not to remove the plastic coverings or packaging materials during the delivery to avoid any corrosion, deterioration & possible damage.
Avoid any mechanical shocks and strokes during handling operations.
All packages for the equipment reaching the site shall be identified as per package list.
Sequence of Installation for the Cooling Towers
Preliminary Checks
Before commencement of cooling tower installation activity, the supervisor/ engineer must ensure that:
All relevant installations for piping is complete and approved by the consultant.
Make sure no damage has occurred during the storage and shifting to the location of installation.
Permission to start the work / civil clearances been obtained from the main contractor/consultant.
All relevant shop drawings and details are available on the site and these are already approved by the consultant.
Installation of cooling tower shall only commence when all associated works by the civil has been completed.
Safe access shall be provided by the Main Contractor, verified through work permit system in coordination with the Safety in charge at site.
Assembly of Cooling Tower
Single-Cell Installation (Two Piece Section Assembly)
Remove any accessories shipped in the cold water basin.
Position the lower section on the unit supports and bolt in place.
Wipe any moisture and dirt from the perimeter mating flanges of the lower section.
Install foam seal tape supplied with the unit on the mating flanges of the lower section in a continuous line. At each corner, allow 1” overlap.
Assembly can be completed using either internal or external drift pin guides.
Internal Drift Pin Alignment (Recommended)
Using drift pins in the drift pin guides provided, guide the top section on to the bottom section.
Match marks must line up.
Bolt the top sections onto the bottom sections using the bolting channels.
External Drift Pin Alignment (Alternative)
Before lowering the upper section onto the lower section, be sure to line up the bolt holes using drift pins, no fewer than one hole at each edge. Guide the upper section onto the lower section starting with a bolt hole at one corner and following down the flange.
Match marks must line up.
Secure the upper section in place to ensure leak free operation.
Flume Box Installation Procedure
Position the cell on the unit support and bolt in place.
Wipe down the surface adjacent to the flume opening of the cell to remove any dirt or moisture that may have accumulated during shipment.
Wipe down flanges on both ends of the flume box.
On one end, apply a layer of flat butyl sealer tape around the face of the flange over the centreline of the holes.
Do not overlap or stretch too thinly at the corners.
When it is necessary to splice the sealer tape, be sure to press the two ends together to form a smooth, continuous strip.
Apply a second layer of flat butyl sealer tape over the first layer following the same procedure.
Using drift pins to align the bolt holes, place the flume box over the opening in the basin of the cell.
Fasten into place. Insert the 3/8” self-tapping screws or bolts in each hole from the flume box into the basin wall and backing strips (if applicable).
Apply two layers of flat butyl sealer tape to the other end of the flume box.
Wipe down the surface adjacent to the flume opening of the cell to remove any dirt or moisture. Position the cell on the unit supports.
Using drift pins to assure alignment, draw cell tight against the flume box.
Repeat above procedures for the other remaining cells whenever necessary.
Positive Closure Plate Installation Procedure
The optional positive closure plate and gasket can be furnished on multi-cell units to allow individual cells to be isolated for cleaning and routine maintenance.
Plate ships loose inside the cold water basin. Procedure for installation are as follows:
Remove nuts and flat washer from the flume box.
Position the neoprene gasket and positive closure plate over the bolts and fasten in place with 3/8” wing nut and flat washers.
When the cooling tower operation does not require use of the positive closure plate, remove the closure plate and gasket. Retighten the flume box using the wing nuts and flat washers.
Fan Guard Installation
Due to height limitations on truck shipments, the fan guard may ship un-mounted. Never step or walk on the fan guard when installed. Installation procedures are as follows:
Mount fan guard to the unit. Existing 3/8” stud & nut for guard mounting at fan deck level shall be used. (3/8” x 1 ½” bolt for guards mounted on top of cowl extensions)
Gradually tighten each nut alternating from one to the other until 20-25 ft.-lb. of torque has been achieved.
Fan guard must be securely in place before the cooling tower is placed in operation.
Top Inlet Piping Installations
All piping supports, design, installations & furnishing shall be as per the approved shop drawings for HVAC System.
Field piping should be fabricated at the time of unit installation. Pre-fabrication of pipe work is not recommended.
Required static pumping head from base of cooling tower is indicated by static lift dimension and piping friction losses.
When tower is equipped with safety railing package, inlet piping should be designed to clear the railing. Adjust static lift as required.
For units installed on vibration isolation rails, flexible connections should be installed in the piping just before the tower perimeter.
Supply piping to cooling tower inlet connections may be supported from the tower structure only at the pipe support locations shown.
Piping must not be supported by the tower inlet connections. Piping outside the perimeter of the tower must not be supported from the tower.
Supply piping supports must be designed to rest on the walls of the hot water distribution basins.
Maximum diameter of inlet header piping that can be supported by the cooling tower distribution basins is 14”.
Provide adequate space between cooling tower and riser piping to allow for entry into the cooling tower access doors.
Motor Location and Conduit Installation
Conduit must be water tight and pitched downward to allow condensation to drain away from fan motor conduit box, therefore, do not run the conduit through fan deck.
All wiring must be as per the approved materials & or conforms to local and national electrical codes. Junction box/ safety switch and all conduits from fan motor conduit box to be sized provided and installed as per the project specifications & approved materials by qualified personnel only.
Rigid conduits outside casing panel must turn down to junction box.
On multi-cell units, use separate conduit lines for each fan motor. Run conduit through adjacent cells to junction box and or disconnect switch on front/ rear cell.
General Installation Guidelines for Cooling Tower
Prior to moving the cooling tower at site, ensure that the foundation requirements have been done.
Foundation details & requirements for the cooling towers shall be as per approved shop drawings or as recommended by the manufacturer as follows:
Mounting pads or a concrete foundation must be available prior to shifting cooling tower at site.
Ensure that the foundation will be able to support the cooling towers at its full operating weight.
Seven-eighths (7/8”) holes are provided in the bottom flange of the basin section for bolting the unit to the support beams.
Units must not be moved to an area which is not accessible to the crane.
All units can be hoisted one after the other without waiting time.
After ensuring that the foundations for the cooling towers are satisfactory, shift the units by means of cranes or rigging equipment.
Before rigging any unit, the weight of each section should be verified from the unit, some accessories add additional weight to the units.
All units are un-crated and brought to the place from where they are hoisted.
Ensure that Rigging instructions are followed as per below manufacturer’s recommendations:
Unload/ uncrate lower & upper sections and move within reach of the crane.
Note: The lower section, which is the basin section, will be one section. The upper section, which is section with fan, will also be one section.
Unload the railings, ladders & platforms and move within reach of the crane.
Install the hand railing on the upper sections while the unit is still on the ground level.
Install the motor platform on the upper sections.
Install the fan motor, shaft and gear box coupling on the upper section.
Hoist lower basin sections and put on foundation or steel grillage.
Install foundation bolts.
Put sealing tape on the circumference of the top of the lower flanges.
Hoist lower basin sections and put them on top of the lower sections using drift pins to align them properly.
Fasten the upper sections to the lower basin sections with tappers.
Install the access door platforms and ladders.
Install the internal ladders (access to internal service platform).
Install the external ladders with safety cages to the top of the units.
Connect & finish the perimeter handrail around the top of the units.
Ensure that the lifting cables are capable of supporting the entire weight of the cooling tower.
Failure to properly lift the unit could result to serious injuries & damage of the unit.
After placing the units with its proper location, all units must be protected against accidental damage by falling building debris, cement or sand getting into the building.
Ensure that units with plastic fills and drift eliminators may NOT be covered with a plastic or tarpaulin when exposed to the sun as this causes a greenhouse effect with very high temperature which may result to damage or deformation of the plastic material.
ATTACHMENTS
- Quality Control Procedure
- Inspection & Test Plan
- Installation Check Sheet
- Risk Assessment
- Cooling Tower Technical Details
- Manufacturer’s Recommendations