Boiler scale is a hard, insulating deposit that forms on water-side surfaces of steam boilers when minerals in feedwater precipitate out under heat and pressure. As water is heated into steam, dissolved calcium, magnesium (from hard water), silica, and other impurities crystallize and cling to boiler tubes and drums. Over time these layers thicken, acting like insulation between the hot fire and the water. Even an “eggshell-thin” film of mineral scale (about 1/32″ thick) can cut thermal efficiency by 2–7%.
As shown above, heavy scale buildup can coat the entire interior of boiler tubes. Such deposits form because hard water chemistry (high hardness, alkalinity or dissolved solids) leads to precipitation of Ca/Mg salts on hot metal. When the water-side surfaces are coated with scale, the boiler must burn more fuel to achieve the same steam output. In fact, industry data confirm that scale dramatically drives up fuel use: for example, a mere 1/16″ of scale can cut boiler efficiency by over 12%, causing plants to spend double-digit percentages more on fuel. Over time these costs – plus increased wear and tear – add up. According to one study, even thin scale can raise annual fuel costs substantially, and heavy scaling in a large facility can translate into six-figure losses or more.
Facilities with robust maintenance programs avoid scale issues more effectively. Continuous improvement is key – for instance, many plants now use online hardness analyzers or send periodic samples to specialized labs for detailed ion profiles. Any sign of drifting hardness or pH should prompt immediate corrective action.
Miura Canada’s Water Treatment and Monitoring Solutions
Preventing scale is a specialized task, and many facilities partner with experts for turnkey solutions. Miura Canada offers integrated water treatment systems and maintenance services designed for steam boilers. Our approach layers automatic softeners (MW-U systems) with secondary anti-scalant feeders and even advanced RO units for high-purity needs.On the monitoring side, Miura Connect provides continuous data and alerts so that facility managers always know the boiler’s condition. Monthly reports help catch any deviation early, which is critical for facilities with multiple boilers or complex steam needs.
