* Hydrocracking unit was undergoing preparation for work
* Plans for overhaul announced in January
* Second HCU to be overhauled at refinery (Adds other unit included, unit descriptions)
HOUSTON, Feb 28 (Reuters) - Valero Energy Corp’s (VLO.N) refinery in Corpus Christi, Texas, began planned work in its west plant on Saturday, according to a notice filed with Texas pollution regulators.
The 315,000 barrel per day (bpd) refinery had been doing preparatory work for a planned shutdown and overhaul of its 36,000 bpd hydrocracking unit in the west plant.
The maintenance was expected to be completed on March 14, according to the notice filed with the Texas Commission on Environmental Quality.
In January, Valero announced it planned an 18-day overhaul of the west plant HCU.
Also in January, Valero performed a planned overhaul of the 15,000 bpd east plant hydrocracker at the Corpus Christi refinery.
A catalytic reformer unit was included in the maintenance, according to the filing.
A hydrocracker uses hydrogen to make motor fuel from oil, especially cheaper heavy, sour crude. A reformer makes high-octane blending components for use in gasoline. (Reporting by Erwin Seba; Editing by Leslie Adler)