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Open-loop condenser water system

System Type: Open-loop condenser water system
Application: Chiller condenser tubes (cooling water side)
Facility: Data Center
Lay-Up Type: Dry (no water left in tubes)

  • Objective
    1. To prevent corrosion, biological fouling, and scaling inside condenser tubes and piping during extended shutdown of the chiller condenser circuit.
  • Materials and Equipment
    1. Compressed air or nitrogen (oil-free, dry)
    2. Non-oxidizing biocide (e.g., isothiazolone or DBNPA)
    3. Corrosion inhibitor (e.g., filming amine or vapor-phase inhibitor)
    4. Spray nozzles or foggers (if using VCI)
    5. Clean lint-free cloths or swabs
    6. PPE (gloves, goggles, etc.)
    7. Labels and tags
  • Procedure
    1. Pre-Lay-Up Preparation
    2. Notify operations staff and isolate the chiller condenser from the system.
    3. Confirm pump lockout and tag all valves and power sources.
    4. Check water chemistry (record pH, conductivity, microbiologicals if possible).
  • Chemical Pre-Treatment (Optional but Recommended)
    1. Dose the system with a non-oxidizing biocide at shock levels (e.g., isothiazolone at 300–500 ppm or DBNPA at 300 ppm).
    2. Circulate for 2–4 hours to kill existing planktonic organisms and treat biofilm.
  • Drain and Flush
    1. Completely drain the condenser tubes and associated piping.
    2. If debris or scale is suspected, flush with clean water or soft water to remove sediment.
  • Remove water from low points using pumps or manual methods.
    1. Air Blowdown
    2. Use dry, oil-free compressed air or nitrogen to blow out residual water in tubes and headers.
    3. Blow until all condensate and visible moisture are eliminated.
    4. Special attention to horizontal piping and dead legs.
  • Corrosion Protection
    1. Choose one of the following:
      1. Vapor-Phase Corrosion Inhibitor (VCI) Fogging
      2. Apply a VCI fogging agent (e.g., Nalco 7978 or equivalent) into condenser tubes and headers.
  • Seal system afterward to retain vapors.
  1. Filming Amine Spray
    1. Spray or fog with a filming amine (e.g., DEHA, morpholine, or Nalco-specific filming agent).
  2. Coat all exposed metal surfaces.
  • Seal the System
    1. Cap or seal all flanges, drains, and vents to prevent humid air or insects from entering.
  • Apply desiccant bags in openings if desired.
  • Documentation and Labeling
    1. Tag the equipment:
      “Dry Lay-Up – Do Not Fill or Start – Date: [MM/DD/YYYY], Chemical: [Name]”
    2. Record lay-up procedure, chemicals used, and date in maintenance log.
  • Periodic Inspection
  • For lay-ups longer than 3 months
    1. Open an access point and inspect every 30–60 days for signs of corrosion, moisture, or odor.
    2. Re-fog or retreat if humidity breach is suspected.Recommissioning
      1. Prior to startup:
        1. Remove seals/caps
        2. Visually inspect internal surfaces
        3. Flush system with clean water
        4. Test for corrosion products (e.g., Fe, Cu)
        5. Re-establish water treatment before resuming operation