Tubercles typically form on what type of pipe material?

Tubercles typically form on ductile iron pipes due to the combination of factors that promote corrosion and biofilm development. Ductile iron is a type of cast iron that is known for its strength and ductility, yet it is still susceptible to corrosion processes when exposed to water and various contaminants in a distribution system.

The formation of tubercles is often associated with localized corrosion, where minera deposits build up over time. This occurs particularly in older water systems where protective linings may have broken down. Tubercles can negatively impact water quality and flow by creating irregularities in the interior pipe surface, leading to increased friction losses and potential points for biofilm growth.

In contrast, materials like PVC and copper are less prone to tuberculation. PVC is non-corrosive and typically doesn’t encourage tubercle formation due to its smooth surface and resistance to corrosion. Copper can develop some oxidation but operates under different corrosion mechanisms compared to ductile iron, usually resulting in patina rather than tubercles.

Understanding the condition of ductile iron pipes is essential for water treatment operators to manage and mitigate issues associated with tuberculation effectively.