DEVELOPMENT AND APPLICATION OF DUCTILE IRON PIPE ELECTRICAL RESISTANCE PROBES FOR MONITORING UNDERGROUND EXTERNAL PIPELINE CORROSION

摘要

The development and testing of low-profile ductile iron electrical resistance corrosion probes are presented. Included are field and laboratory evaluations relating to the corrosion behavior of ductile iron with and without the annealing oxide coating as well as carbon steel in the same testing environments. Also included are corrosion rate reduction and corresponding cathodic protection parameters, and the corrosion protection performance of the annealing oxide with and without standard asphaltic shop coatings. The metal loss, corrosion rate, electrochemical noise and calculated corrosion rate values are compared with pre-exposure probe measurement surface characteristics. At the conclusion of the laboratory testing, physical inspection of the probes were compared with the corrosion rates integrated over the period of the testing. The results presented demonstrate the viability of low-profile ductile corrosion probes as well as quantify the corrosion protection provided by the annealing oxide and asphaltic coatings.