AWWA ACE68557 ✓ Most Recent

The Florida Everglades has been used for conducting accelerated external corrosion testing of iron pipe for over 70 years. It contains some of the most corrosive soils in the world, and is classified by AWWA C105 as a "uniquely severe environment". The Everglades test site utilized in this study not only contains extremely low soil resistivities of less than 200 ohm-cm, but also contains tidal brackish water table fluctuations and high MIC (microbiologically influenced corrosion) activity. This paper reports on the findings of a five year study in this environment to evaluate different types of electrical resistance (ER) probes and to compare corrosion rate results obtained from actual pipe buried in this type of soil. The study evaluated five different types of ER probes (standard steel ER probes with machined test surfaces from three different manufacturers, specially manufactured ductile iron ER probes with a machined test surface, and specially manufactured ductile iron ER probes with an as-cast annealing oxide/peen pattern surface). As the most commonly utilized method of external corrosion protection for ductile iron pipe is polyethylene encasement, corrosion rates were also examined utilizing probes under the encasement and probes buried in the Everglades "muck" adjacent to the test pipe. Comparative results are given in graphs and tables. Includes 16 references, figures. See more