At a silo site, the operator contracted a firm to replace and dispose of the dust removal system filter. The silo was emptied and the installations turned off. A hot work permit was filed. When the subcontractor’s employee began to open the silo by means of flame cutting the filter’s second metal wall, the filter sleeve in back of the wall ignited when exposed to the flame. Another employee present tried to extinguish the outbreak using a fire hose from a cabinet installed nearby for this specific risk. Bothered by the heavy smoke released, he had to abandon the attempt. First responders were called at the same time. On-site fire-fighters with backup successfully contained and then controlled the blaze in just over 1 hour. They ensured complete extinction by monitoring for an extra hour.