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Anyone familiar with boiler water treatment knows that oxygen pitting can be an issue. Accordingly, hydrazine has been a normal part of water treatment programs for highand low-pressure boilers in power plants and many other industrial facilities
However, in treating one problem, hydrazine raises another concern: worker health. Cortec® provides a balancing solution by fighting pitting corrosion with S-15, a safer alternative to hydrazine.
The Consequences of Oxygen Pitting
But why is oxygen pitting a problem in the first place? Dissolved oxygen, which is particularly abundant in high-pressure steam boilers with a regular influx of highly-oxygenated water, readily oxidizes steel, leaving small pits in the metal surface. Over time, this is a serious threat to the integrity of boilers. Long term, it can damage boiler tubes and create leaks. In the short term, corrosion products can clog the system and cause condensate returns and steam traps to malfunction, leading to inefficiencies or repairs. The risk increases with a rise in temperature and pressure. Preventing damage is therefore critical to ensuring good service now and for as long as possible in the future.
Hydrazine: Not a Friendly Option
Traditionally, hydrazine has been used to scavenge oxygen and thereby decrease the chance of metal oxidation. The problem is that hydrazine is a highly toxic compound. Facilities therefore ought to consider other options for corrosion protection in operating boilers where oxygen pitting is a concern.
Total Replacement for Hydrazine Programs
Fortunately, Cortec® Corporation has developed S-15, a lower-toxicity alternative that can completely replace hydrazine programs. S-15 combines volatile neutralizing amines with an oxygen scavenger / metal passivator. This formula works in three main ways. First, it neutralizes acidic species and increases pH, creating an alkaline environment that reduces the risk of acidic corrosion. Second, this alkaline environment allows the oxygen scavenger/passivator to act more quickly to reduce oxygen in the water. Third, S-15 passivates areas that have already started to rust by converting hematite (soft red rust) to magnetite (hard black rust). S-15 also works in the vapor-phase as the boiler water evaporates into steam, carrying S-15 to protect surfaces above the water level, as well as those in direct contact with it.
Other Benefits of S-15
S-15 is easy to feed into the deaerator, feedwater tank, or steam drum. It can also serve as a building block for custom water treatment formulations. S-15 is thermally stable and highly efficient at inhibiting corrosion from oxygen and carbon dioxide. It can be recycled with condensate water and is typically effective at a very economical continuous dose of 2-5 ppm. S-15 does not leave solid residue in boiler systems or compromise steam quality.
Stay One Step Ahead of Pitting and Hydrazine Concerns
Regardless of local hydrazine restrictions, the availability of a safer option demands attention. By choosing S-15 as a building block for your next water treatment formulation or as a main part of your boiler maintenance strategy, you can stay one step ahead of both oxygen pitting and hydrazine concerns. Contact Cortec® to learn more about the benefits and use of S-15 to prevent oxygen pitting in boilers.
