The long-term, economical, and safe operation of industrial boilers is impossible without proper water treatment. Minerals, dissolved gases, and contaminants present in raw water can cause serious problems in the boiler system, including scale formation, corrosion, foaming, and reduced efficiency. That’s why boiler feedwater treatment is not just recommended, but technically and economically mandatory.
What problems can untreated boiler feedwater cause?
- scale formation: calcium and magnesium ions deposit on heat exchange surfaces, reducing heat transfer and increasing energy consumption
- corrosion: dissolved oxygen and carbon dioxide initiate corrosive processes that weaken pipes and boiler shells
- foaming: dissolved solids and oil-based contaminants can lead to foam, which causes boiler water carryover into the steam system
- boiler damage: deposits and corrosion-related issues may result in cracks, leaks, or even boiler explosions
Main steps of water treatment for industrial boilers
- Mechanical pre-filtration
removal of suspended solids using mesh or automatic filters - Softening – Bluesoft water softeners
removal of calcium and magnesium ions via ion exchange (replaced by sodium) or chemical treatment to prevent scale - Reverse osmosis (RO) – leading brands: ARCTON and BLUECLEAR RO systems
removes dissolved salts, organics, and bacteria to produce high-quality boiler feedwater - Deaeration
removal of dissolved oxygen either mechanically (e.g. thermal deaerators) or chemically (oxygen scavengers) to prevent corrosion - Chemical conditioning
application of corrosion inhibitors, pH regulators, and phosphate-based stabilizers to maintain system stability
Monitoring water quality: the importance of the LSI index
In industrial boiler systems, the scaling or corrosive tendency of water can be predicted using a key indicator: the Langelier Saturation Index (LSI).
What is LSI?
The LSI is a calculated value that indicates whether water tends to:
- deposit calcium carbonate (as scale), or
- aggressively dissolve metals (causing corrosion)
Formula:
LSI = pH – pHs, where pHs is the pH at which water is saturated with calcium carbonate.
| LSI value | water behavior | consequence |
| > +0.5 | strongly scaling | risk of scale – heat loss, clogging |
| +0.2 to +0.5 | slightly scaling | acceptable, but requires monitoring |
| -0.2 to +0.2 | balanced, neutral | ideal boiler water |
| -0.2 to -0.5 | slightly corrosive | minor risk of metal damage |
| < -0.5 | strongly corrosive | high risk of pipe failure, boiler corrosion |
What affects the LSI?
- water pH
- calcium ion concentration
- alkalinity (carbonates)
- temperature
- total dissolved solids (TDS)
Important: LSI is not a standalone metric, but a guide that helps fine-tune water treatment when combined with regular lab testing and monitoring.
What are the benefits of proper boiler feedwater pretreatment?
✔️ reduced scale and corrosion formation
✔️ less downtime and lower maintenance needs
✔️ higher efficiency and lower operating costs
✔️ extended lifespan of boilers and piping
✔️ compliance with industrial and environmental regulations
Summary
Industrial boiler water treatment is not just a technical task – it is the foundation of cost-effective operation. By regularly monitoring the LSI index and using modern filtration, desalination, and chemical conditioning technologies, serious damage can be prevented and long-term, safe equipment performance ensured.
Operating a boiler at your facility? entrust the water treatment to professionals – this is where efficiency begins.
