The 18" ductile pipe in this system was lined with Protecto 401, a ceramic epoxy designed for lining ductile iron pipe and fittings. Protecto 401 is resistant to sewer liquids and gases and resists undercutting from exposed edges. A 24" cement lined ductile iron sewer pipe, installed at the treatment plant where the 18" line discharged, was exposed to the same environment. Partially full sewers produce hydrogen sulfide which forms sulfuric acid and attacks all cementious linings. The concentration of hydrogen sulfide in this system increased the rate of attack on this cement lined pipe.

Protecto 401 lined ductile coupon cut from crown of the pipe 4' south of replaced manhole. No effect on pipe or lining from sewer liquids or gases (some edge damage on coupon caused by abrasive cutting.)

Cement lined ductile iron pipe cut from treatment plant. No effect below flow line, severe corrosion above flow line.