OREANDA-NEWS. February 16, 2015. Production on a large crude distillation unit (CDU) at Exxon Mobil Corp's 344,600 barrel-per-day (bpd) Beaumont, Texas, refinery has been reduced due to thinned piping, said two sources familiar with operations at the plant.

The sources did not know by how much production was reduced on the 240,000-bpd Crude B Unit, which is the larger of two CDUs doing the initial refining of crude oil coming into the refinery and providing feedstock for all other units, the sources said.

In addition to the CDU, a 45,000 bpd coking unit, a 16,000 bpd alkylation unit, a 4,200 bpd dewaxing unit and 5,000 bpd gas treating unit, are operating at reduced levels due to thinned piping at the refinery.

An Exxon spokesman said operations were normal at the refinery.

Thinned piping was one of the causes of a large fire in 2012 at Chevron Corp's refinery in Richmond, California, according to the US Chemical Safety Board.

A coker increases the amount of refinable material in a barrel of oil and converts residual crude to petroleum coke, a coal substitute.

An alkylation unit converts refining byproducts into octane-boosting gasoline additives. A dewaxing unit removes undesirable elements from distillate feedstocks. A gas treating unit removes pollutants from gases produced in crude oil refining.