Pollution
Humain
Environnement
Economique

In a plastics production plant, a silane leak occurred on a transfer station. A container of phenyltrichlorosilane on a car was in place at the station, its 2 articulated arms ready for the transfer process by means of nitrogen pressure being connected at the level of the dome. The technician pressurised the container; shortly thereafter, 3 of the HCl detectors placed in the vicinity of the station activated an alarm that was immediately acknowledged by the technicians, who shut down the transfer station as an emergency measure (closure of transfer valves and container depressurisation). The internal emergency plan was triggered at 5:45 pm. The internal response unit shared among several local plants quickly arrived and covered the transfer operation retention basin with a foam and then the entire transfer zone in order to limit HCl dispersion. As a precautionary measure, the unit then set up water curtains on the side of the external circulation lanes and the buildings located onsite. According to the operator, the volume of this leak was less than 50 l of phenyltrichlorosilane, while the HCl emissions remained very limited (whitish cloud confined to the area adjacent to the transfer station and retention basin). Moreover, the lack of wind plus the water curtains made it possible to guarantee the absence of any effects beyond the site’s borders. Once the incident had been brought under control, the container’s connection arms were unhooked, and it was observed that the liquid arm connection joint had not been evenly clamped and got “stuck”, thereby explaining the pressurised liquid leak. In addition, just a single technician was present to launch the transfer operation. The chlorosilane that spilled on the ground was collected by a gutter surrounding the transfer station and connecting to a neighbouring retention pit, which was shared across several installations. The effluents collected (chlorosilane + foam) were pumped and channelled towards the site’s neutralisation station. The emergency response teams (composed of in-house fire-fighters and ancillary onsite fire-fighting resources) washed and cleaned the sector as well as the car. Upon their arrival, the Classified Facilities Inspectorate had been alerted, then once the incident had been handled, the operator issued a press release to the town hall, county prefecture and the local newspapers. Subsequently, the Inspectorate proposed that the Prefect request the operator to submit a detailed incident report, in analysing the cause(s) and sequencing, in addition to offering remedial actions to prevent a repeat occurrence. Moreover, the operator initiated an action plan relative to: the transfer operation guidelines (written reminder to qualified technicians of critical points in the guidelines), introduction of a sealant test prior to opening the car’s valves, training in jointing for technicians involved in the transfer process. Modification to the raised pit (compartmentalisation), schedule