In the chemical environments common in energy production plants, steel pipes and equipment can accumulate layers of iron sulfide, some of which are corrosion resistant and provide protection to the steel surface. Understanding how operating conditions affect steel surface layers can improve corrosion rate estimates, decreasing building and maintenance costs, and increasing the safety and reliability of operating plants. Chevron Energy Technology Company (Chevron ETC) is currently studying the link between operating conditions and corrosion properties at ALS to determine which corrosion layers form and in what order.