Motiva Enterprises (MOTIV.UL) is scheduled to shut the large crude distillation unit (CDU) and large coker at its 626,000 barrel-per-day (bpd) Port Arthur, Texas, refinery by Monday, people familiar with the company’s plans said on Friday.

Motiva will shut the 350,000 bpd VPS-5 CDU and the 110,000-bpd DCU-2 coker for planned overhauls of the units expected to take 45 days to complete, said the three sources.

A Motiva spokesperson did not reply to a request for comment.

In November, Motiva moved the overhaul’s scheduled start from March to January to avoid DCU-2's having an unplanned shutdown because of failing equipment.

VPS-5, the largest of three CDUs at the refinery that break down crude oil into feedstocks for all other units, also needs equipment repaired and replaced, the sources said. The addition of VPS-5 in 2012 more than doubled the capacity of the refinery, the nation's largest.

VPS-5 feeds residual crude oil to DCU-2, which converts it into either motor fuel feedstocks or petroleum coke, which can be a substitute for coal.

A sulfur recovery unit will also be shut for work while the CDU and coker are shut, the sources said.