Shell prepares to shut Norco refinery hydrocracker for overhaul -sources

(Adds details on unit, length of shutdown)

HOUSTON, Jan 19 (Reuters) - Royal Dutch Shell Plc (LSE: 0LN9.L - news) is preparing to shut the hydrocracking unit over the weekend at its 225,800 bpd Norco, Louisiana, refinery, said sources familiar with plant operations on Friday.

"Shell (LSE: RDSB.L - news) routinely plans maintenance on its assets in an effort to ensure we continue to operate in a safe and reliable manner," said company spokesman Ray Fisher, who declined to discuss planned maintenance at the Norco refinery.

The 40,000 bpd hydrocracker is scheduled to be shut for at least a month for the work, the sources said.

Hydrocrackers use hydrogen, high heat and pressure along with a catlyst to convert gas oil to motor fuels, primarily diesel.

(Reporting by Erwin Seba; Editing by James Dalgleish, Grant McCool)