Cover Story Part 2 Using Corrosion as a Process Variable Monitoring and analyzing historical corrosion data can provide insights not available from manual inspection and measurement techniques Jake Davies Emerson Automation Solutions IN BRIEF A VERY COMPLEX CHARACTERISTIC MEASURING AND MONITORING METAL LOSS THE VARIABILITY OF METAL LOSS A CASE IN POINT REAL-WORLD LESSONS LEARNED S 40 ome petroleum refiners looking for ways to improve profitability have lately turned to buying opportunity crudes from secondary sources. These crudes, while priced less than more premium feedstocks, often contain various contaminants, including solids and corrosive compounds. Such contaminants can damage processing equipment by corroding and eroding it from the inside out (Figure 1). In the worst case, a pipe wall may become progressively thinFIGURE 1. Unique corrosion issues can arise when petroleum refiners swap feedstocks ner over time until the pressure causes it to break open - hot hydrocarbons that are perhaps higher than the auto-ignition temperature can escape and mix with air, resulting in a potentially serious safety and environmental incident. This is an extreme case, but not without precedent in the global petroleum refining industry. Opportunity crudes presCHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM MARCH 2019http://WWW.CHEMENGONLINE.COM