Monitoring and Mitigation of

Government retains for itself, and others acting on behalf, a paid-up, nonexclusive, irrevocable worldwide license and said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The purposes of this project are to (1) minimize the environmental discharge of hydrocarbons and treatment chemicals due to failures resulting from sustained localized pitting corrosion, (2) reduce the use of toxic treatment chemicals used by field operators to prevent those failures, and (3) identify treatment approaches that reduce the use of toxic chemicals. The approach in this project has been to develop an on-line, real-time method to monitor sustained localized pitting so that treatment chemicals (e.g., biocides and chemical inhibitors) can be applied only when needed. In addition, field operators need to know whether pitting corrosion is due to microbiologically influenced corrosion or other chemical corrosion mechanisms so that they can appropriately apply either biocides or corrosion inhibitors only if needed using minimal treatment applications. Argonne National Laboratory (ANL) has been developing an instrument that can be used by field operators to allow them to make such decisions in real-time while minimizing toxic discharges and treatment chemical use. This instrument has also been used as a tool to evaluate less toxic treatment approaches. Many unexpected failures in pipelines and storage vessels can be traced to sustained localized pitting (SLP) corrosion. Detecting such pitting is often difficult because standard corrosion probes can only measure generalized corrosion, not the localized corrosion that can drill holes into metal. Argonne used both laboratory and field experiments to design a corrosion probe that detects rapid SPL corrosion by taking electrochemical noise measurements. Argonne researchers have reexamined electrochemical noise (ECN) analysis of localized corrosion by using hardware, signal collection, and signal processing designs that are different from those used in conventional ECN analysis techniques. The new data acquisition system was designed to identify and monitor the progress of SLP by analyzing the power spectral density (PSD) of the trend of the corrosion potential noise level (PNL). The results of the PSD analysis consistently demonstrated that the trends of PNL contain information that can be used to differentiate between SLP corrosion and general corrosion mechanisms. The degree of linear slope in the low-frequency portion of the PSD analysis was correlated with the SLP corrosion process. Laboratory metal coupons, as well as commercial corrosion probes, were …