At around 3.45 a.m., a spill of 2,600 litres of acetonitrile (flammable solvent) occurred during a product transfer operation in a pharmaceutical plant. When arriving at the operations room to close the bottom valve of the receiving tank and stop the transfer operation, the technician noticed a leak of liquid flowing down through the levels. Due to the flow of liquid, the technician could not enter the room to close the valve. The technician then activated the emergency shutdown switch in the control room and activated the manual call point, which triggered the internal emergency plan alarm and evacuation of the workshop. The facility was secured by opening a fire hose cabinet. The discharge valve leading to the Rhône was closed. The discharge was removed to the chemical sewer and then to the toxic waste basin of the wastewater treatment plant. The measurements performed confirmed a high concentration of VOCs in the workshop. The internal emergency plan was lifted at 5.25 a.m.

The spill was caused by a configuration defect in the transfer circuit between the receiving tank and the reactor. The technician responsible for setting up the circuit did not have the information. At the same time, the technician had made an alignment error. The adjacent branch connection had a reference similar to that of the usual line. The technician therefore incorrectly thought that the resulting transfer circuit complied with the manufacturing sheet. Finally, the technician performed a pressure test before transferring the product, which the technician determined was compliant, but test execution did not comply with the standards recommended for this workshop and did not make it possible to detect leaks in the line.

After the incident, the operator took the following actions:

• sharing of information on the current arrangements with the teams through a room posting;
• further raising of technicians’ awareness regarding pressure tests;
• test of the knowledge of production technicians and implementation of a specific training module on pressure tests;
• sharing of incident feedback;
• further technician training in performing pressure tests;
• ongoing development of a dedicated training module on pressure tests;
• in-house emailing of a newsflash giving feedback relating to this event, stressing that this pressure test is a key safety step.

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