Walter Louis Fluid Technologies
Industrial Water Treatment Newsletter
October, 2012
Cooling Tower Layup Procedures
Why do it?
Most cooling towers and condenser water piping are made of steel and require chemical treatment to protect against corrosion. Throughout the cooling season your equipment is protected by Walter Louis’ treatment program. But what about during the off season? If drained and left untreated, condenser water pipes will develop general surface corrosion that will lead to mill scale. Mill scale builds up and eventually flakes off and collects in tower distribution pans as rust/scale chips. These rust/scale chips clog downcomers resulting in overflowing distribution pans, low cycles, increased water usage and corrosion rates, and ultimately shorter equipment life.
Another problem facing cooling towers when not properly laid up is under-deposit corrosion. Sediment brought in by air pulled through by the tower fan accumulates in the tower sump. This is part of the normal operation of a cooling tower and the quantity deposited depends on the air quality, location of the tower, load, and run time of your equipment. As deposits accumulate in the tower sump, they create differential electrolytic cells and barriers to chemical passivation that can accelerate the corrosion rate and decrease the life cycle of the cooling tower.
How do I do it?
The cooling tower lay up procedure must be done at the end of each cooling season and coordinated with your shutdown date. The procedure is simple and the treatment is inexpensive. In the days prior to tower shutdown and draining, lower the cycles of concentration to allow the tower to bleed out solids and suspended matter. The cooling tower should now be drained and cleaned to remove any remaining solids. Refill and restart the tower and with the tower circulating, add 5 gallons of WLFT #1248 to the tower for every 1,000 gallons of condenser water system volume. Allow the tower to circulate for 24 to 48 hours and then drain the tower as usual. All tower and piping surfaces will be passivated and protected against further corrosion during the off-season.
Why do I have to drain the tower?
The tower must be drained to prevent the water from freezing and rupturing the tower sump and associated piping systems. Anti-freeze measures are not effective because evaporation reduces the effectiveness within weeks. Glycol-based products should not be discharged to your sewer system.
Is there anything else I need to do?
If the system has an outside water meter or the meter is in an unheated area, it must be removed because water can accumulate in the meter and associated piping and cause the meter to rupture. Water meter removal should be a routine part of the tower lay-up procedure.
What do I do before startup?
The WLFT #1248 Lay-up does not interfere with your startup procedure. Simply fill the tower as usual and begin your usual operation. Mill scale problems will be reduced and your equipment life cycle will improve.