Fire crews were called out to put out a fire in an industrial oven in Fulwood on Sunday night.
Crews from Preston and Penwortham raced to the Jonesco plastics manufacturing plant in Pittman Way around 11.31pm.
The fire had been controlled by the plant’s sprinkler system.
Lancashire Fire and Rescue Service said without the sprinkler system the fire would have spread to adjacent machinery and products stored in racking.
Firefighters spent two hours fighting the fire, which destroyed the oven and caused some smoke damage to the warehouse.