Interior view of an industrial cooling tower, showing pipes, a large fan above, and metal structures with signs of rust and water residue on the surfaces.

View of an industrial interior showing metal pipes, a grated walkway with railing, and corrugated metal walls, with light coming from an open circular hatch above.

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Why Cooling Tower Layup Matters

“Cooling tower layup” refers to preparing an open-recirculating cooling tower system for extended low-use or shutdown periods, especially when freezing risk is present. The goal is to preserve integrity, mitigate corrosion, prevent biological growth, and avoid freeze-related damage.

A good layup strategy supports reliable spring startup, reduces unplanned maintenance, and extends equipment life. Because “layup” is a precise technical term used in water treatment and maintenance literature, optimizing your content around cooling tower layup helps connect with facility engineers and decision-makers seeking procedural guidance.

Risks of Poor Layup or Inadequate Freeze Protection

If layup or freeze mitigation is neglected or poorly executed, a facility may encounter:

Ice damage: Freezing water in basins, pipes, nozzles, or fill can crack or deform structural components.
Frozen piping & valves: Residual water trapped in headers, distribution lines, or control valves can burst under ice expansion.
Accelerated corrosion: Stagnant water, especially with oxygen ingress, promotes pitting, general corrosion, and microbiologically influenced corrosion (MIC).
Biological proliferation: Stagnant volumes create ideal habitats for microbes, including Legionella, which can grow during idle periods if untreated.
Delays & repair costs: Damage discovered during spring startup can force shutdowns, replacements, or major cleaning campaigns.

In designing a robust layup plan, pay particular attention to dead legs, equalization piping, and trapped volumes—these are often overlooked stagnation zones.

Two Modes: Seasonal Layup vs. Winter Operation

When thinking about layup, your facility may fall into one of two scenarios:

1. Seasonal Layup (Full Shutdown)

Used when cooling load drops near zero in colder months (e.g. office buildings, schools). The objective is to take the tower offline safely and protect all wetted components until next season.

2. Winter Operation with Partial Layup

Used in mission-critical facilities (data centers, hospitals, manufacturing) that must maintain some cooling through winter. Here, a modified layup protocol is maintained in tandem with ice control strategies.

A comprehensive layup plan should address both modes, as seasonal shutdowns sometimes get delayed or extended unexpectedly.

Step-by-Step Layup Procedure for Seasonal Shutdown

Here’s a recommended, detailed layup (shutdown) procedure:

1. Pre-Layup Planning & Assessment

Review the tower’s O&M manual and identify drain points, nozzles, bleed lines, equalization piping, and instrumentation.
Stock spare parts like gaskets, nozzles, valves, and structural components before shutdown.
Schedule maintenance windows before freezing weather.

2. Pre-Shock Disinfection & Clean-Out

One to two weeks ahead, reduce cycles of concentration or increase blowdown to purge solids.
Apply an oxidizing biocide or combined biocide to reduce microbial load and break biofilm.
Circulate for 12–48 hours to allow dispersion.

SolidBlend provides a layout of similar steps in their “Cooling Tower Layup” guidance document.

3. Drain, Flush & Clean

Completely drain basins, distribution piping, headers, sumps, and any low points.
Use compressed air, vacuum or flushing to remove residual water, especially in dead legs.
Pressure-wash fill, drift eliminators, and internal surfaces. Remove scale, sediment, or debris.
Clean all strainers, screens, and intake baskets.

4. Inspect & Repair

Examine components (nozzles, gaskets, fill media, fans, structure) for damage, corrosion, or wear.
Replace or repair as needed.
Lubricate fans, gearboxes, and bearings following manufacturer specifications.

5. Corrosion Control & Layup Chemistry

Wet layup option: Refill a minimal volume of treated water and add a corrosion inhibitor / filming amine package to maintain passivity on wetted surfaces.
Dry layup option: Ensure surfaces are fully dry. Use desiccants or inert gas blanketing in enclosed zones if feasible.
Add a non-oxidizing biocide or residual biocide if any water remains.
Consider mild agitation (recirculation) to avoid settling of solids.

6. Isolate & Drain Auxiliary Lines

Drain chemical feed lines, equalization lines, bypass lines, makeup water lines, and control loops.
Leave drain valves open to allow residual water to exit.
For lines in unheated zones, engage heat tracing or insulation as needed.

7. Cover & Insulate

Use tarps, insulation blankets, or custom covers over basins, fan openings, and louvers to prevent ingress of snow, ice, or debris.
Seal access panels or structural openings if practical.

8. Documentation & Handover

Record all actions: chemicals dosed, inspections, parts replaced, conditions, and timeline.
Provide this log to operations and maintenance teams for reference at spring startup.

9. Monitor During Layup (Optional)

In some critical applications, periodic checks (weekly or monthly) of residual chemistry (pH, inhibitor levels) help maintain passivity.
If power is available, gentle mixing or circulation may be used to prevent stratification.

Several industry sources describe these same steps under “shutdown layup” or seasonal layup procedures.

Strategies for Winter Operation with Layup in Place

When a system continues operating through winter, but portions are to be in layup or low-use, these strategies help integrate layup and ice protection:

Maintain water movement: Always keep minimal circulation in layup zones, because still water freezes and stagnates faster.
Hot-bypass flow: Route warm return water through idle cells or basins to keep them above freezing.
Basin heaters & heat tracing: Use immersion, electric, or steam heaters in basins and apply trace heating to exposed piping and nozzles.
Fan cycling & VFD control: Cycle fans or throttle speed to avoid extreme overcooling of recirculating water.
Cell rotation / staging: Alternate which cells are active and which are in layup mode, allowing each to rest or be treated while others handle load.
Ice patrol inspections: Schedule frequent walkthroughs to spot ice buildup early and manually remove slush or frozen accretions.

These hybrid layup–operation strategies ensure that even when parts of the system are idle, freeze risk is managed.

Water Treatment Adjustments During Layup

Proper chemistry is essential during layup, whether seasonal or winter-operation mode:

Biocide residuals: Maintain a residual (oxidizing or non-oxidizing) to prevent microbial growth, even in cold water.
Corrosion inhibitors: Use filming inhibitors (e.g. molybdate, phosphate, azole, amine blends) tailored for stagnant conditions to protect wetted surfaces.
Scale control: While colder water generally reduces scale risk, localized heated zones (bypasses or traces) may still precipitate solids—monitor and maintain scale inhibitor residuals.
Layup-specific additives: Use formulations designed for layup (buffered, sequestration, stabilized inhibitors) to maintain passivity during stagnation.
Cycle and conductivity control prior to shutdown: One best practice is lowering cycles of concentration ahead of shutdown to reduce solids load and make flushing easier. SolidBlend’s layup protocol suggests adjusting conductivity ahead of drain.
Monitoring fugitive volumes / dead legs: Pay extra attention to lines, dead legs, or equalization piping. Keep them flushed or dosed to avoid microbial or corrosion “hot spots.”

For reference, the U.S. government’s EPA / DOE Best Management Practices on cooling towers discusses the importance of controlling conductivity, blowdown, and cycles of concentration in general cooling tower operation.

Also, cooling tower treatment and layup protocols are covered in government-adapted design manuals such as “Cooling Water System Start-Up and Layup Requirements” within broader cooling water engineering guides.

Mechanical & Operational Best Practices

Beyond chemistry and procedural layup, mechanical and operational readiness is critical:

Test basin heaters and heat tracing early and ensure they function before first freeze.
Lubricate and inspect fans, drives, belts, gearboxes, motors—cold conditions magnify wear or failure.
Drain or purge all auxiliary piping, bypass loops, and control lines, eliminating trapped water zones.
Install or verify insulation, panel covers, and physical storm protection for exposed components.
Before spring startup, flush the system, re-commission chemical feed systems, validate sensor calibration and residuals, and confirm flow paths.

Key Takeaways for Facility Managers

Use “cooling tower layup” as your internal term for seasonal shutdown/low-use procedures—it’s a precise term that aligns with industry practice.
Develop both seasonal layup and winter operation protocols so your facility is prepared for either scenario.
Chemistry is as important as mechanics—don’t neglect biocide or corrosion inhibitor planning during layup.
Pay extra attention to hidden or dead-leg piping, which can become stagnation and corrosion sites.
Document everything—procedures, chemical doses, repairs, and observations. That record is invaluable at restart.
If needed, partner with a water treatment provider to design layup chemistry, monitoring plans, and technical support.

Speak with our Water Treatment Experts today.