Incident of the air valve nut of the hydrogen booster K-4001/1 falling into the cylinder and causing cylinder damage

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Incident of the air valve nut of hydrogen booster K-4001/1 falling into the cylinder and causing damage to it. Incident name: Incident of the air valve nut of hydrogen booster K-4001/1 falling into the cylinder and causing damage to it. Time of occurrence: 10:34 on October 16, 1995. Sequence of events: At 10:34 on October 16, 1995, Shen Dayi, the operator in charge of the compressor, heard unusual noises coming from the compressor room; he immediately went there and found that the operating booster K-4001/1 was producing mechanical impact sounds and there was a significant leak of hydrogen. He promptly activated the emergency shutdown mechanism to stop the unit, thereby preventing an accident. At the same time, other crew members also rushed to the scene to close the inlet and outlet valves of the unit, opened the glass windows for ventilation to prevent hydrogen buildup that could lead to fires or explosions, and started the backup unit. A post-inspection revealed that the back cap of the air valve nut on the east side of the K-4001/1 outlet had fallen into the cylinder, causing cylinder collision. The collision caused a tear in a flange weld on the compressor’s liquid removal line, and the crankcase was split over a length of approximately 400 mm; thanks to the timely shutdown, a major accident was avoided. Cause analysis: Immediate cause: The back cap of the air valve nut on the east side of the K-4001/1 outlet fell into the cylinder, resulting in cylinder collision. Precautions 1. The maintenance of the unit must ensure quality ； 2. If abnormal mechanical impact noises are detected in the unit, an emergency shutdown should be carried out immediately, followed by starting the backup unit. If the backup unit cannot be started right away, the procedure for shutting down the pressurizer in hydrogenation operations shall be followed. 3. In the event of a hydrogen leak, the inlet and outlet valves of the unit should be closed to cut off the gas supply, and ventilation measures should be taken to prevent the accumulation of flammable gases ； Knocking and similar actions are prohibited to prevent the creation of ignition sources.