A gas boiler exploded in a facility manufacturing concrete elements for construction. After having detected the smell of gas the previous day, the operator called upon the services of a boiler maintenance company that had sealed a small leak at the gas heating device on the morning of the accident. Since the smell persisted, the operator subsequently had a gas supply company intervene urgently. The explosion occurred before the gas company arrived. The company’s heating system was damaged resulting in an internal operational loss. The operator planned to set up gas detectors along with an automatic cut-off valve in the boiler room. The natural gas supplier was also consulted for direct connection to the natural gas network instead of a gas tank to supply the boiler.