Oxygen corrosion in boiler systems is one of the most common and damaging issues industrial and commercial facilities face. Left untreated, oxygen corrosion can lead to severe and costly equipment damage, characterized by distinct pitting patterns.
Understanding Oxygen Corrosion in Boilers
Oxygen naturally dissolves in water supplies, reaching maximum saturation levels determined by temperature. At elevated feedwater and boiler temperatures, even trace amounts of dissolved oxygen can significantly accelerate corrosion, causing extensive damage much faster than at ambient conditions.
Key Areas Susceptible to Oxygen Corrosion
While the entire preboiler, boiler, and postboiler system is potentially at risk, corrosion typically first appears in specific areas:
- Economizer: Oxygen corrosion commonly begins here due to rapid temperature increases. Other vulnerable spots include deaerator storage sections and feedwater lines, though these areas are often challenging to inspect.
- Steam Drum: Maximum corrosion occurs at the steam/water interface in the steam drum, where oxygen is released. Oxygen that does not react at this stage flashes over with the steam.
- Condensate Lines: Oxygen corrosion is frequently visible here, becoming significantly more severe in the presence of carbon dioxide, a common contaminant in condensate returns.
While these areas are easier to monitor, understanding the risk throughout your entire system is essential.
Effective Strategies for Controlling Oxygen Corrosion
Controlling oxygen corrosion effectively requires a two-fold approach: mechanical deaeration and chemical deaeration.
Mechanical Deaeration
Mechanical deaerators heat water and vent dissolved gases, reducing oxygen content by more than 99% to parts-per-billion concentrations. Even these minute levels can be problematic, requiring supplementary chemical treatment for complete protection.
Proper mechanical deaeration is critical to any successful boiler water treatment strategy, improving both operational efficiency and reducing the risk of downtime and costly maintenance.
Chemical Deaeration
Chemical deaeration is essential for eliminating residual oxygen from boiler feedwater. Selecting the appropriate chemical oxygen scavenger depends on several critical factors:
- Sulfite-Based Scavengers: Commonly used due to cost-effectiveness, rapid reaction speed, and ease of handling. However, sulfites are generally unsuitable for boiler pressures above 900 psig.
- Non-Sulfite Scavengers: These alternatives minimize dissolved solids and are ideal for high-pressure systems, often providing dual benefits of scavenging oxygen and protecting metal surfaces from general corrosion.
- Desuperheating Applications: When feedwater is used for desuperheating, low-solids non-sulfite oxygen scavengers are preferred to prevent deposits in the superheater.
Customizing Your Boiler Water Treatment Plan
Choosing the right oxygen control program requires a thorough understanding of your boiler's specific operating conditions, including any periodic system shutdowns. Boilers stored in wet or dry conditions remain susceptible to corrosion, emphasizing the need for comprehensive protection.
Watertech’s dedicated technical engineers collaborate closely with you, conducting detailed site evaluations to develop tailored, effective solutions that boost efficiency, enhance safety, and ensure compliance.
Partnering with Watertech: Your Trusted Expert
At Watertech of America, Inc., protecting your boiler system means safeguarding your operations. Our expertise combines advanced chemistry, innovative equipment, personalized service, and remote monitoring technologies like WTLink, ensuring optimal system performance and longevity.
Ready to safeguard your boiler from oxygen corrosion? Contact Watertech today for an expert site evaluation.
