(Adds Motiva declines to comment in paragraph 4, background inparagraphs 5-6)
HOUSTON, June 30 (Reuters) - Motiva Enterprises completed planned maintenance on hydrotreaters and repairs on a200,000 barrel-per-day (bpd) crude distillation unit late lastweek at its 600,000-bpd Port Arthur, Texas, refinery, sourcesfamiliar with refinery operations said on Monday.
The CDU, called VPS-4, is one of three units at the refinerythat does the initial refining of crude oil coming into therefinery and provides feedstock for all other units.
The largest CDU, the 325,000-bpd VPS-5, was in operation butat slightly reduced production levels while the hydrotreaterwork was under way.
A Motiva spokeswoman declined to discuss operations at therefinery.
The hydrotreating units remove sulfur from motor fuels andother refined products to comply with U.S. environmentalregulations.
The Motiva Port Arthur refinery is the largest in the UnitedStates. Motiva is 50-50 joint venture between Royal Dutch ShellPlc and Saudi Aramco. (Reporting by Erwin Seba; Editing by Lisa Shumaker and JanPaschal)