HOUSTON: Royal Dutch Shell Plc shut the gasoline-producing residual catalytic cracking unit (RCCU) at its 227,400 barrel-per-day (bpd) Norco, Louisiana, refinery on Friday, sources familiar with plant operations said on Monday.

The 112,000 bpd RCCU, which converts residual crude oil into unfinished gasoline, was shut to repair a leak, the sources said.

A Shell spokesman did not have information immediately available about operations at the Norco refinery on Monday morning.

The RCCU repairs led Shell to issue a notice to nearby residents on Thursday that the Norco refinery and chemical plant complex would using the safety flare system because of maintenance on a unidentified unit.

Safety flares are used to burn off hydrocarbons that cannot be processed normally because of unit shutdowns or startups.

The RCCU, unlike the more common fluidic catalytic cracker (FCC), uses residual crude oil from distillation units to make unfinished gasoline. FCCUs use gas oil as their feedstock.