Explosion on a hydrogen compressor of a silane manufacturer

An explosion occurred at a hydrogen compressor of a polysilicon plant. The head of the compressor was blown off and the released hydrogen exploded causing extensive damage to the building and to surrounding piping and equipment. The consequence was the release of Trichlorosilanes (TCS). This compound converts to hydrochloric acid (HCl) when released into the atmosphere.
It was estimated that approximately 1,784 pounds of HCL were released during the event (5000 pounds is the maximum legally allowed).
Two employees were light injured as a result of firefighting activities.

The compressor had been revamped by installing a new 24-inch head piston with a 24-inch piston. The new piston failed during operation.
The detailed series of events:
7 September, 3:47 PM equipment failure in the compressor room of the hydrogen recovery building. The piston in one of the cylinder failed and allowed hydrogen gas to enter an adjoining variable frequency drive room. The control room operator stopped the process and halted the flow of process gasses to the compressor.
7 September, 4:00 PM the hydrogen gas that had entered the variable frequency drive room was ignited by an electrical component, resulting in an explosion and subsequent fire. The company firefighter teams were deployed.
8 September, 4:00 AM, emergency response activities were completed.

The INITIATING CAUSE was the mechanical failure of the piston of one of the hydrogen compressor cylinders.
The administration in charge concluded that the incident was due to a “sudden and unavoidable failure of process equipment” and classified it as malfunction. In this case, the ROOT CAUSE would be the same as the immediate cause. However, the fact that the new piston failed after only 127 days of operation suggests that something went wrong during the manufacturing or design phase

piston, cylinder,compressor

The compressor had been modified few months before the incident, by replacing a piston of the compressor cylinders. The new piston had a diameter of 615 mm allowing to increase throughput in respect to the old 525 mm piston. The new piston failed after only 127 days of operation.

The sources are not agreeng on the number of affected people. Some report only 2 light injuries among firefighters, other speak of 13 people with light respiratory difficulties due to HCl.
The amount of hydrogen released is unknown.
Almost 800 kg of HCl were released, as consequence of the hydrogen explosion.

The administrative rules of the Tennessee Comprehensive Rules and Regulations defines a malfunction as any sudden and unavoidable failure of air pollution control equipment or process equipment, or for a process to operate in an abnormal and unusual manner. The evidence suggested that the September 7, 2017 incident was due to a sudden and unavoidable failure of process equipment.
Because the event meets the definition of a malfunction, and it is unlikely that public health or the environment were impacted due to the excess HCL and TCS emissions, the administration in charge recommended that no enforcement action be taken for the excess emissions resulting from the event.

Following the explosion, the facility suspended operations. It planned to re-install the old piston which had correctly functioned till the moment of its replacement.