Many people believe that boiler scale is merely “impurities adhering to the heat transfer surfaces” and consider it insignificant. In reality, however, scale poses significant hazards: not only does it reduce boiler thermal efficiency and increase operating costs, but it can also damage boiler components and lead to serious safety incidents. Below, we will explain the hazards of scale in detail—please be sure to take this seriously.
Hazard 1: Reduced boiler thermal efficiency and increased fuel consumption. Scale has a very low thermal conductivity—only 1/10 to 1/50 that of steel. Once scale adheres to heat transfer surfaces, it impedes heat transfer, preventing heat inside the boiler from being transferred promptly to the working fluid (water or heat transfer oil). To achieve the required temperature and pressure, more fuel must be consumed, thereby increasing operating costs. For example, a 1 mm layer of scale can reduce boiler thermal efficiency by 5%–10%. Over the long term, this results in significant fuel waste.
Hazard 2: Causes overheating, deformation, and pipe bursts in boiler components. When scale adheres to heat transfer surfaces, it causes localized overheating that exceeds the temperature tolerance of steel, leading to deformation and bulging of these surfaces (such as water-cooled walls and heating coils). In severe cases, this can result in pipe ruptures and bursts, triggering safety incidents. In steam boilers in particular, scale-induced pipe bursts can cause serious casualties and property damage.
Hazard 3: Accelerates corrosion of boiler components and shortens their service life. The presence of scale damages the metal surfaces of the boiler’s heat transfer surfaces, forming corrosion cells that accelerate metal corrosion. This leads to problems such as corrosion pits and perforations in the heat transfer surfaces, shortening the boiler’s service life. Additionally, impurities in the scale further exacerbate corrosion, increasing maintenance costs and may even necessitate the premature replacement of boiler components.
Hazard 4: Causes unstable boiler operation and affects energy supply. Scale clogs boiler pipes and blowdown ports, hindering the circulation of the working fluid. This results in significant fluctuations in boiler pressure and temperature, compromising the stability of the energy supply and, consequently, affecting production. Furthermore, scale flaking off may block pipes, interrupting circulation and causing malfunctions.
Hazard 5: Increases safety risks and causes safety incidents. Problems caused by scale, such as pipe bursts and corrosion-induced perforations, can lead to working fluid leaks. Leaks of high-temperature, high-pressure working fluid can result in safety incidents such as scalding and explosions. Additionally, scale blockages in pipes can cause a sudden rise in boiler pressure, exceeding the safety valve’s capacity and triggering explosions.
Note: The hazards of scale must not be overlooked. Proper water treatment and regular descaling should be performed to prevent scale buildup, ensuring the safe and efficient operation of the boiler and avoiding malfunctions and safety incidents caused by scale.
