Planned maintenance has begun on units at Exxon Mobil Corp’s 344,600 barrel per day (bpd) Beaumont, Texas refinery, a spokesman said on Saturday.

“Certain units have been shut down for planned maintenance,” said Exxon spokesman Patrick Trahan. “We have communicated with our customers and plan to meet all contractual obligations.”

Sources familiar with plant operations told Reuters on Friday that the refinery has shut a 110,000 bpd crude distillation unit for a revamp lasting between 60 and 70 days to prepare for an eventual expansion of the refinery.