HOUSTON (Reuters) - Valero Energy Corp was repairing a coker feed tank at its Port Arthur, Texas, refinery shortly before the residual crude oil inside burst into flames on Tuesday, sources familiar with plant operations said on Friday.
Tank 108, which partially melted from the heat of the burning residual crude inside, was initially damaged last week by a malfunction, the sources said.
A Valero spokeswoman did not reply to a request for comment on Friday.
The coker and small crude distillation unit (CDU) remained shut on Friday at the 335,000 barrel per day (bpd) Port Arthur refinery, which was days away from restoring production after being shut three weeks earlier by Tropical Storm Harvey.
It was unclear what role the damage or repair work, if any, may have played in causing the blaze, the sources said.
Also unknown on Friday was how long the 75,000 bpd CDU and the 100,000 bpd coker will remain shut, the sources said.
Trade sources said they expected at least a two-week shutdown of the two units, cutting production at the Valero refinery.
No injuries were reported due to Tuesday’s blaze, which was extinguished about an hour and a half after it broke out, the sources said.
CDUs do the primary refining of crude oil in a refinery and provide feedstock to all other production units.
Cokers convert residual crude oil from distillation units into feedstock for motor fuels or petroleum coke, which can be used as a coal substitute.
Reporting by Erwin Seba; Editing by James Dalgleish