Boiler Descaling - Best Practices

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Boiler Descaling Best Practices


The following provide basic procedures for descaling your boiler.

NOTE: Follow all local regulations for discharge. Do not dump used DESCALING SOLUTION without neutralizing to at least pH 7.0.



  1. The boiler has to be taken offline and boiler pressure dropped to zero.
  2. The Main Steam valve has to be secured (Closed), so no product/water solution leaves the boiler and gets into the steam system. The valve has to be shut tight and must not leak.
  3. The safety valve on the boiler is removed and a 1/2" hose, or similar connection made from that outlet back to the external recirculating reservoir/system, which will be used to add the ScaleBreak product.
  4. Have a vent arrangement on the top of boiler to remove gasses. The vent must be made so, as to stop the circulating water from going through the vent.
  5. The boiler feed water pump must be isolated by a valve. Also, the pressure control system and sight glass valves should be isolated.
  6. The bottom blowdown valve on the boiler can be used to connect to the discharge of the recirculating pump. This is where the product mix will enter into the boiler at the bottom. Install a check valve on the discharge of circulating pump, in case the pump failed, the product/water mix will not flow back out of boiler and flood room.
  7. Take a sample of the scale from the boiler and keep for tests.
  8. ScaleBreak is added to water in the mixing tank until the boiler is full and water starts to be returned to the mixing tank. Only add enough water and product to the mixing tank to cover pump suction.
  9. The mixing tank should only be half full so that when the returning water comes back, any gas does not overflow the mixing tank.
  10. Start the recirculating pump and pump the product into the boiler from the bottom.
  11. If the boiler could be started for a short period to raise the recirculating water temperature to 120 - 140°F, this would increase the acid reaction time. If the boiler was just taken offline, the water temperature should be hot enough.
  12. The circulation should continue for at least 8 hours.
  13. Monitor the acid strength in the mix tank, when the acid level has dropped, add more acid to mix tank.
  14. When satisfied, add a neutralizing compound (see neutralization instructions) to the mix tank to raise the PH to 7.0 as a "best" practice.
  15. Stop the pump circulation and drain water from the boiler, after the cleaning is complete.
  16. Open Steam Drum hand hole and flush from the top in all areas with water, using a pressure hose.
  17. When Flushing from the top is complete, flush also the Mud Drum in all areas, with a pressure hose.
  18. Replace all Hand Hole Gaskets with new ones, refill boiler with soft water opening the feed water pump valves.
  19. Open steam valve and other valves - feed water, sight glass, and pressuretrol.
  20. The fresh, new water in boiler should be soft water and have chemical treatment.
  21. Start the boiler and make sure no leaks are occurring.
  22. Follow normal boiler start up on low fire.
  23. Manually blowdown boiler more often for the next 3 days, to remove any loose scale that might have lodged at bottom of the boiler.
  24. When boiler goes back online, check areas for steam. If steam is not going to certain areas, check steam lines for water and drain.


When performing a ScaleBreak cleaning, make sure you use effective safety equipment, which will include goggles, shoes and a mask. Always make sure you have adequate access to water for wash off, in case of emergency. Always have someone with you and quick access to water, for flushing your body, in case of a spill. The room should also have good ventilation. Never carry out this procedure without a buddy system in place. Always read Material Safety Data Sheets and keep on hand during cleanings.