Definition - What does Descaling mean?

Descaling is the process of removing scale from equipment such as boilers and heat exchangers. It involves the removal of thick layers of oxides formed on metals at elevated temperatures.

Descaling is needed when a heat exchanger accumulates a significant thickness of calcium on its surface, enough to insulate the water from the heat source and impair performance.

Periodic descaling of industrial heat exchangers' tubes is necessary to inhibit corrosion and improve efficiency.

Descaling safely and effectively removes:

  • Limescale
  • Calcium
  • Rust
  • Water scale buildup
  • Mud
  • Other non-soluble deposits

Corrosionpedia explains Descaling

Scaling is problematic because it forms on the inside of pipes and reduces the cross-sectional area available to carry water or liquids. In addition, scaling can form on equipment and on hot water heaters, causing corrosion-related problems. To avoid this problem and enhance performance, descaling is needed.

There are two types of descaling in boilers:

  • Cleaning the corrosion deposits from the radiator system and main heat exchanger of a boiler
  • Cleaning hard water deposits out of a combi-boiler

The former is more accurately described as powerflushing. Powerflushing and descaling are closely related because the same equipment and chemicals are used, even though the faults being addressed are different.

A descaling agent or chemical descaler is used to remove limescale from metal surfaces in contact with hot water, such as in boilers, water heaters and kettles. Descaling agents are typically acidic compounds such as hydrochloric acid that react with the alkaline carbonate compounds present in the scale, producing carbon dioxide gas and a soluble salt.

To remove scale, either the heat exchanger must be replaced, or descaling acid pumped though it for an hour or two. It is a much simpler procedure than powerflushing as only one item (the heat exchanger) needs attention. The powerflushing pump is set up and connected to the heat exchanger via the washing machine hot and cold taps, turned on and the scale is gradually dissolved away.

Descaling lengthens the life of equipment through prohibiting scale buildup and inhibiting corrosion.

Connect with us

Corrosionpedia on Linkedin
Corrosionpedia on Linkedin
"Corrosionpedia" on Twitter

Sign up for Corrosionpedia's Free Newsletter!