In a medical prosthesis factory, a tank had been drained during a test on a new chemical cleaning line. During this process, a solution of hydrofluoric acid (HF) and a hydrogen peroxide (H2O2) was released. The product leaked through an oven that was not equipped with a retention basin. Roughly 240 litres of product spilt onto the ground over an area of 40 m².

The staff (300 people) evacuated the site, and the power was switched off. Seven employees who had inhaled vapours were attended to by the emergency services. The sewers were blocked. The spilt product was absorbed, recovered in a plastic bin and then handed over to a specialised company for processing. Recovery operations were carried out with chemical suits.

The line trials were carried out in the presence of an external service provider. A prevention plan for the intervention was drawn up, detailing the measures to be taken in the event of an incident. Nevertheless, the investigation carried out by the facility operator, and its subcontractor highlighted the following points:

• the design of the new line was incorrect (connection of the oven to a drain circuit),
• the sectional valve of the drain system had been closed the day before by the subcontractor (human error).

These 2 causes blocked the flow of the product and caused it to rise to the level of the oven.

Following the events, the operator compiled an assessment of the possible ways of impro, among which include:

• the acceptance of the line by a third party expert before re-testing,
• testing with water,
• an increase in the stocks of absorbent materials,
• inspection of the gas detection (HF) facility.

Finally, it was noted that the following preventive measures were proven to be effective:

• absorbent materials and anti-pollution kit to combat the spread of the product,
• shut-off devices on the water networks,
• organisation and training of personnel in chemical risks (rapid evacuation of personnel).