(Adds details about refining center operations and outages, background about 2012 explosion, paragraphs 2-7)
By Marianna Parraga
HOUSTON, April 9 (Reuters) - Venezuela's largest refining center is working at 67 percent capacity, a slight decline compared to January even though state-run PDVSA restarted two of its crude distillation units in recent months, according to an internal document seen by Reuters on Wednesday.
The 955,000 barrel per day (bpd) Paraguana Refining Center (CRP), which includes the Amuay and Cardon refineries on Venezuela's western coast, has had frequent operational problems since a big explosion in 2012 that killed more than 40 people.
The complex was working at 70 percent capacity in January. But with a crude distillation unit running partially, the flexicoker undergoing unplanned maintenance and another 10 units halted, its output declined to 643,000 bpd as of March 27, the document said.
The document said the 645,000 bpd Amuay refinery, the world's fourth largest, has five operational units out of service, including the 72,000 bpd flexicoker. Also, distillation unit No. 3 was runnning less than 10,000 bpd of crude, compared to normal processing of 87,000 bpd.
Amuay's crude distillation unit (CDU) No. 4 was restarted in January, PDVSA workers said, and CDU No. 3 was restarted in February, after several problems since December.
According to the document, the 310,000 bpd Cardon refinery stopped its alkylation and isomerization units on March 4 for major planned maintenance. Another four operational units at that refinery were also out of service by the end of March.
The 16,000 bpd Bajo Grande refinery at Zulia state, also connected to the CRP, is working partially while repairs are done to a pipeline going to one of its docks. High inventories were reported at that refinery. (Reporting by Marianna Parraga; Editing by Terry Wade and David Gregorio)