The blaze occurred about 9 p.m. Wednesday at the Equinox Chemicals Plant in Albany.
A 37-year-old worker, Jason Pate, sustained second- and third-degree burns over 60 to 70 percent of his body.
Investigators said Mr. Pate was operating a machine when two gasket seals ruptured and ignited a tank filled with acetylene.
Company officials suspended production temporarily until they finish an internal investigation.