Carbon steel piping components in refineries throughout the U.S. are susceptible to highly
variable sulfidation corrosion rates. Carbon steel piping is manufactured to meet certain
specifications, including American Society for Testing and Materials (ASTM) A53B,17 ASTM
A106,18 and American Petroleum Institute (API) 5L.19 ASTM A53B and API 5L do not contain
minimum silicon content requirements for carbon steel piping,20 while ASTM A106 requires the
piping to be manufactured with a minimum silicon content of 0.10 weight percent. As a result,
manufacturers have used different levels of silicon in the carbon steel pipe manufacturing
process. Thus, sulfidation corrosion rates could vary depending on the manufacturing
specification for silicon content in the carbon steel installed in refinery processes. In the mid-
1980s, pipe manufacturers began to simultaneously comply with all three specifications, so most
carbon steel piping purchased since then for refinery operations likely has a minimum of 0.10
weight percent silicon content. However, over 95 percent of the 144 refineries in the U.S.,
including the Chevron Richmond Refinery, were built before 1985. Therefore, the original
carbon steel piping components in these refineries likely contain varying percentages of silicon,
so they may experience highly variable sulfidation corrosion rates.