The Westlake Chemical facility in the Sulphur-Carlyss area will experience flaring for the next several hours, a company spokesman said.
Joe Andrepont, senior community affairs representative for Westlake Petrochem, said the flaring could continue through Friday night and into Saturday morning.
No shelter-in-place was issued, and there were no injuries or any off-site impacts.
Several KPLC viewers said the flaring began Thursday night and was louder and larger than normal.
Andrepont said workers had to do a minor repair on an ethylene unit. To do that, they had to shut the unit down.
"When a unit goes down, you flare for safety," Andrepont said. "You go to the flare again for safety when you bring it back up."
According to the EPA, a flare is an important safety device, particularly at processing plants. In an emergency situation where equipment or piping becomes over-pressured, special valves on the equipment automatically release gas through piping to flare stacks. In the absence of safety flares, plants would be at higher risk for fires and explosions.
Flaring is also very common when shutting down or starting up a unit, the EPA said.
"We apologize for any inconvenience this may have caused our neighbors," Andrepont said.
Calcasieu OEP Director Dick Gremillion confirmed that his office has not received any report of off-site impact.