In a chemical plant, fire broke out on a conveyor belt being disassembled and placed in an upper position within a bulk storage unit for fertilisers and ammonium nitrates. The internal emergency plan was activated: the neighbouring firm providing the site’s fire protection services came to the premises and controlled the blaze within 40 min. The intervention of external responders, called in as backup, was not required. The warehouse’s smoke extractors were turned on, yet the nitrogen oxide detectors were left off. No consequences were recorded on stored products since the conveyor was located away from the storage zones. Property damage focused on the 5 linear meters of burned belt. Work conducted at hotspots (oxygen-propane cutting torch) caused this accident: the same morning, subcontracted technicians had been assigned to remove this former conveyor belt, which was in disuse for several years and whose materials were neither fire-resistant nor antistatic. When these technicians were offsite for a lunch break, the fire ignited. The Classified Facilities Inspectorate noted several irregularities, including a lack of subcontractor certification for hotspot works, procedural flaws during establishment of the hot work permit (preliminary hazard analysis, task safety analysis, mandatory precautions to remove all inflammable materials or products from the workplace, scheduling of inspection rounds following the works, etc. were not completed), and the absence of a fire network grid.