A- OXYGEN SCAVENGERS
Oxygen scavengers are added to boiler water to remove oxygen and prevent corrosion. 20 Litre is sufficient to treat 5,000 L of boiler water, and can capture the oxygen content of 1,400 L of air. Oxygen scavengers adjust the pH of boiler water to between 8.5 and 9.0.

B- Sludge conditioners:
If the boiler is not maintained properly, suspended particles tend to settle at the lining of the system. If left untreated, it can drastically reduce the boiler efficiency. A sludge conditioner is often used to remove and clean the boilers. In some instances, it is also used to prevent and control scale formation.

C- Corrosion Inhibitors
One of the major issues that affect the operations of industrial boilers is an accumulation of salt deposits on the internal lining of the system. As a part of the equipment maintenance, scale and corrosion inhibitors are used. The common inhibitors are catalyzed sodium bisulphite, carbohydrazide, diethyl hydroxylamine, and cyclohexylamine. Oxygen scavengers also work well as scale and corrosion inhibitors.

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Corrosion Inhibitors fall in to four main types:-
1- Anodic Inhibitors
This type of corrosion inhibitor acts by forming a protective oxide film on the surface of the metal. It causes a large anodic shift that forces the metallic surface into the passivation region, which reduces the corrosion potential of the material. Some examples are chromates, nitrates, molybdates, and tungstate.
2- Cathodic Inhibitors
These inhibitors slow down the cathodic reaction to limit the diffusion of reducing species to the metal surface. Cathodic poison and oxygen scavengers are examples of this type of inhibitor.
3- Mixed Inhibitors
These are film-forming compounds that reduce both the cathodic and anodic reactions. The most commonly used mixed inhibitors are silicates and phospates used in domestic water softeners to prevent the formation of rust water.
4- Volatile Corrosion Inhibitors (VCI)
VCI are compounds being transported in a closed environment to the site of corrosion by the process of volatilization from a source. For example, in boilers, volatile compounds such as morpholine or hydrazine, are transported with steam to prevent corrosion in condenser tubes.

D- ANTISCALANT OR SCALE INHIBITOR
Antiscalants prevent precipitation of crystallized mineral salts that form scales inside boilers. In boilers, scaling is caused by impurities being precipitated out of the water directly on heat transfer surfaces or by suspended matter in water settling out on the metal and becoming hard and adherent. Scale deposition reduces system efficiency and makes the boiler unsafe to operate as well as causes tube failures, restrict circulation, overheating, reduce system efficiency, and compromise boiler system's reliability.