UPDATE 2-Exxon expects little impact from Beaumont upset

HOUSTON, May 22 (Reuters) - Exxon Mobil Corp (XOM.N) said it expects little impact from a Friday coker malfunction to production at its 348,500 barrel per day (bpd) Beaumont, Texas, refinery a spokeswoman said.

"The refinery anticipates there will be minimal impact to production," said spokeswoman Kathleen Jackson.

Exxon took coker drum No. 6 out of service on Friday at the Beaumont refinery after a crack was discovered in the drum, which allowed pollution to escape from the unit, according to a notice filed with state pollution regulators.

A coker increases the amount of motor fuel made from a barrel of oil and converts gunky unrefinable residual oil into petroleum coke, a coal substitute, in giant drums that function under high heat and high pressure.

Five other drums continue to operate in the coking unit, Jackson said.

Coke drums are susceptible to cracking because of the conditions under which they operate. Cracked drums are either replaced altogether or repaired.

Jackson said no decision had been made on the method for fixing the cracked drum. (Reporting by Erwin Seba; Editing by Richard Chang)