Texas City emergency manager Bruce Clawson says the two people who were injured in the incident Friday night were in good condition.
Valero Energy Co. spokesman Bill Day could not say whether there had been an explosion or a fire during the failure without further investigation.
The worker who died and one of the injured were Valero employees. Day says the other injured person was a contract worker who was taken to a hospital in Texas City.
After the boiler failed, Day says the plant continued operating and there was no environmental damage.
The refinery employs about 480 people.