Corrosion of Ductile Iron Drain Piping

[KenRad]

I have a system of floor drains that serves a cafeteria. All drain piping is ductile iron. This week, we had a P-trap that developed a hole in the side of it, and began to leak over a production line. When we removed the trap and inspected it, there was an area about 2" x 2" that could be pushed in with your finger.

Does anyone have any idea what would cause drain piping to do this? The system is only 15 years old. This particular drain line is 3", and serves a number of softdrink dispensers. To my knowledge, there has never been any drain chemicals put into the system.

Thanks in advance!

---KenRad

 

[Metalguy]

Did you observe any small pits near the area? As I see this, you either have an oxygen-driven corrosion problem, a possible acidic environment (I think Cokes are acidic), or a possible MIC problem. Were there any deposits on the ID, and what did they look like? Any bad odors from the drain?