Causes & Harms of The Boiler Scaling

December 17, 2019


In modern industry and life, a boiler is an indispensable piece of equipment. It provides a continuous and stable supply of heat energy. However, in the process of boiler operation, we often face an easily overlooked problem - boiler scaling.

When we take a closer look at boiler scaling, it's not just a matter of mineral deposits. It's a hidden danger that lies beneath the surface. It can lead to reduced energy efficiency, wasted energy, and shorter equipment life. It can even have far-reaching environmental and economic impacts. In this article, the EPCB team will look at the root causes of boiler scaling. We will also explore the potential hazards and the steps we can take to effectively prevent and address the problem.

What is boiler scaling?

Boiler scaling is caused by impurities in the feedwater. They settle on the boiler's heat transferor or metal surfaces. During evaporation, these deposits become hard and concentrated. This prevents heat transfer and eventually leads to localized overheating, forming so-called "hot spots". The main culprits in this problem include contaminants in the water. These contaminants include calcium, magnesium, iron, silicon, and aluminum.

Contaminants in water are not completely insoluble in boiler water. They reach the surface in soluble form, then precipitate during evaporation. The presence of calcium and magnesium salts is believed to be the main cause of boiler scaling. High concentrations of silica affect the alkalinity of boiler water. Scale usually consists of carbonates, bicarbonates, and sulfates. It forms gradually in concentrated form, reducing heat transfer efficiency. It should not be overlooked that it is difficult to completely remove scale. Chemical treatments can't fully eliminate it.

Different types of scale have different characteristics. Carbonate deposits are usually granular or porous. Sulfate deposits are denser, with smaller bonded crystals. High silica deposits are very hard. They have tiny crystals. This leads to the formation of dense scale in boilers. These different scale characteristics affect heat transfer to varying degrees. They increase the risk of boiler operation. Effective scale removal and prevention require considering factors such as water quality, temperature, and chemical treatment.

Causes of boiler scaling

Boiler scaling is a complex problem involving many factors. Its formation is closely related to several factors. The following are some of the main reasons that may lead to boiler scaling:

Feed water quality: The quality of feed water is one of the main causes of boiler scaling. Low-quality feedwater can form scale and deposits in the boiler. This is especially true for those containing high levels of hardness and iron. Boiler manufacturers strongly recommend pretreatment of feedwater. This includes water quality analysis. It also involves removing suspended or dissolved solids through filtration. It also involves softening or desalination processes.

Contaminated Condensate: Condensate forms when steam returns to a liquid state and is used to reduce make-up water and fuel costs. However, if condensate is contaminated or improperly treated, it can contribute to boiler scaling.

Boiler Pressure: The pressure at which a boiler is operated directly affects scale formation. Boiler manufacturers often recommend operating within the ideal chemical characteristics and pressure range. This ensures that the boiler will perform optimally

Boiler design: Different boiler designs may have different effects on scaling. Certain designs may be more susceptible to fouling. Boiler design and efficiency may be one of the main factors contributing to fouling.

Irregular Boiler Maintenance: Irregular maintenance and negligence of feedwater treatment can lead to scaling. Boiler systems need regular inspection, cleaning, and maintenance to work properly. Neglecting maintenance can harm both the boiler and the process plant.


Boiler scaling is a serious problem that can negatively affect boiler performance and equipment life. Neglecting scaling may lead to an insulating effect that slows down heat transfer. This affects thermal efficiency and may even cause steam boiler piping to overheat and rupture. Therefore, taking effective preventive measures is key to ensuring efficient boiler operation for a long time.


EPCB, a company with superior technology and specialized manufacturing experience, has achieved a prominent position in boiler manufacturing. EPCB is committed to providing high-quality boiler products. Its products meet international standards and focus on innovation and high performance. EPCB achieves this through continuous research, development, and technological upgrades. This ensures that customers' needs for reliable, efficient, and safe boilers are met. EPCB's products are designed and manufactured with active consideration of water treatment and other factors to minimize the possibility of scaling. This helps prevent boiler scaling.


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