The fire blaze erupted at the Reliance Industries plant at Patalganga Rasayani in Raigad, located around 51 km from here, on Sunday night when one of its units was activated after a month-long halt. There was a spark in a chemical stored in the unit which led to the fire in a boiler. It was a minor fire at a plant which was under maintenance. The fire was allowed to continue because of the need to do away with residual hydrocarbon. There have been no injuries.