API 571 Certification (Corrosion & Materials) Practice Test

Carbon steel (CS) demonstrates the lowest resistance to sulfuric acid corrosion compared to the other materials listed. This is due to its composition, which lacks sufficient chromium or nickel content to provide a protective oxide layer against aggressive environments such as sulfuric acid. When exposed to sulfuric acid, carbon steel can undergo rapid corrosion, leading to substantial material loss and potential failure.

On the other hand, stainless steels like 316L SS contain higher amounts of chromium and nickel, which enhance their corrosion resistance, especially in acidic environments. High Silicon Cast Iron offers improved corrosion resistance due to the presence of silicon, which can form a protective silicate layer. Alloy C-276 is specifically designed to resist a wide range of corrosive media and is particularly strong against sulfuric acid. Therefore, carbon steel, due to its susceptibility to acid attack, stands out as having the lowest resistance among these options.