What is descaling?
Descaling is the chemical removal of mineral scale — mostly calcium carbonate — from heat-exchange surfaces, cooling tower fill and pipework. It uses an inhibited acid that dissolves the scale while a corrosion inhibitor protects the base metal underneath, followed by neutralisation and flushing.
Scale is an insulator. A layer under a millimetre thick can measurably cut heat transfer, which shows up as rising approach temperature on a cooling tower, longer chiller run times and higher energy bills long before anything visibly fails.
The chemistry is an acid — commonly inhibited hydrochloric or sulphamic — circulated through the system. The inhibitor is what makes it usable: raw acid would dissolve the scale and then attack the tube walls. Progress is tracked by monitoring pH; when the acid stops being consumed, the scale is gone.
The job is not finished at that point. The system must be neutralised, flushed until the effluent runs clear and neutral, and then passivated or immediately returned to treated service, because a freshly descaled surface is bare and will corrode quickly.
