A storage bin overheated at a malting plant. On 14 August, technicians spotted a clog in a storage bin whilst 40 t of malt was being transferred from it to the malt silo for loading onto a train. The malt was not flowing well. A thermal imaging camera indicated a temperature of 25–30 °C, which was similar to that in the neighbouring bins. The temperature was monitored. On 16 August, attempts were made, without success, to transfer the malt to the silo by scraping the malt. At around 4:00 p.m., the malt at the centre of storage bin dropped, proving that it had heated up. The temperatures measured ranged between 60 and 80 °C and unusual odours were detected. The operator called the firefighters and suppliers to inert the storage bin. However, because the lower explosive limit (LEL) had been exceeded and given the delivery times, inerting could not take place. All the power supplies were cut. Foam was poured from the storage bin’s top and its bottom was sprayed. A worker received a minor injury to one finger. The neighbourhood was evacuated, rail traffic was halted for nearly 2.5 hours and the N151 highway was closed for five hours. After the temperature and the LEL concentration had dropped, the malt was emptied on 17 August from 1:00 a.m. to 3:00 p.m. The employees resumed work on the same day. Because the neighbouring storage bins were affected by the cooling operations (water and foam), a total of 130 t of malt was lost. A specialist company cleaned the buildings and the courtyard.

The malt overheated due to its characteristics and the extremely hot weather (nearly 40 °C for several days). This specific type of malt, which is used little at the plant, has a higher moisture content than other malts (7% instead of 4–5%). Its colouring is darker. Its higher sugar concentration caused it to caramelise along the outer edges during kilning. The operator noticed clumps at the degerming outlet. The heating time is six hours longer than for traditional malts. The temperature of the malt is not checked when it leaves the kiln to be loaded into the silo. At the time of the incident, the malt had been in the storage bin for 10 days. According to the safety report, temperature probes are not necessary because the malt remains in the storage bins for no more than 48 hours.

This type of malt is not produced whilst outdoor temperatures remain high. The operator took the following measures:

• the malt is turned during the drying stage to prevent it from aggregating;
• temperature sensors were fitted in the six bins designated for holding special malts;
• a production monitoring sheet complete with specific monitoring and production instructions for this type of malt was created;
• a procedure for controlling kilning operations and giving the actions to take if non-uniform layers and a high moisture content are found was written;
• carbon dioxide granules (for inerting the bins) were obtained;
• malt must be transferred after 48 hours in the bins.

The inspection authorities for classified facilities required the operator to carry out a risk analysis before commencing operations to produce any specific malt. The site’s emergency response plan was revised. First responders must be trained and instructed in implementing it, particularly regarding shutting off the site’s water supplies.