ExxonMobil's 637,400 b/d Beaumont, Texas, refinery experienced a process upset involving a hydrocracker unit, the company reported in an environmental filing.

The incident began at 12:26 p.m. on Sunday and lasted about an hour, according to the report filed with the Texas Commission on Environmental Quality.

Refinery operators said in the report filed Sunday that they expected to meet all contractual commitments.