The Chevron Richmond Refinery 4-sidecut piping circuit containing the 52-inch component that
failed was constructed of ASTM A53B carbon steel, which had no minimum specification for
silicon content. Post-incident testing of samples of the 4-sidecut piping from the Chevron
Richmond Refinery identified silicon content ranging from 0.01 weight percent to 0.2 weight
percent. Of 12 samples taken from the 8-inch and the adjacent 12-inch 4-sidecut line, six had a
silicon concentration of less than 0.10 weight percent. The 52-inch pipe component that ruptured
on the day of the incident had a silicon content of only 0.01 weight percent. The elbow
component directly upstream of the 52-inch component that failed had a silicon concentration of
0.16 weight percent, showing considerably less thinning.