Accident investigation revealed deficiencies in EURENCO Vihtavuori Ltd´s identification of chemical risks

Fire damage at EURENCO Vihtavuori Ltd's gunpowder factory in Laukaa (Finland) was caused by the rapid combustion of vaporized ether. No specific reason for the fire was identified during the accident investigation conducted by the Safety and Chemicals Authority (Tukes), but it was presumably caused by static electricity or a hard bump that caused sparks. At the time of the accident, there were exceptionally high concentrations of highly inflammable ether in the atmosphere, which suddenly burst into flames. During the accident, which occurred in May 2012, two workers were injured, one of whom sustained severe burns. Tukes’ accident investigation detected deficiencies in the company's ability to assess chemical risks, implement changes and comply with  instructions.   

According to Tukes' investigation team, the fire was not caused by a single error, but rather by a combination of factors. All of the factors leading to the accident had already been present for several months.

The fire occurred during the gelatinization process in the factory, which is the first phase in gunpowder production. During gelatinization, the main raw material, nitrocellulose, is mixed with stabilizers and other chemicals to form a paste-like mass, with the help of ether and ethanol.

At the time of the accident, the two workers involved were filling a gelatinizing mixer with the powder mass, which had already been processed once and which consequently contained readily inflammable ether. The recycled powder mass had also been mistakenly placed in a non-conductive barrel, despite the fact that the mass should be handled in electrically conductive barrels.

Tukes detected deficiencies in the company's ether risk assessments. The company had not made sufficient efforts to minimize the volume of ether, and ether risks had mainly been regarded as an occupational hygiene problem. The ether concentration had also increased because the exhaust ventilation system had not been turned on while the mixer was being filled. In addition, the ether in the barrels used to transport the powder mass had not been identified as a risk.

Tukes' investigation group states in its report that EURENCO Vihtavuori Ltd has a well-documented management system, but it is not fully complied with. In major accident hazard industries, deviating from instructions is a serious deficiency.

The investigation team recommends that the following measures should be taken to avoid similar accidents:

• When identifying hazards and assessing risks, chemical safety should also be taken into account as strictly as explosives safety. The risk assessment group requires expertise in the field of chemical and production processes, and the workers at the site should be consulted.
• Established instructions should be followed. Regular training should be arranged and monitored to ensure that workers are aware of the instructions and are observing them. Important chemical and process safety instructions include the clarification of organizational responsibilities, identification and assessment of risks, management of change, work instructions, and the handling of emergencies.
• Changes affecting the organization, designated responsibilities, personnel or processes should be communicated effectively in order to ensure the continued functionality of the organization. Responsible persons within the organization, as well as those planning and implementing the changes must be familiar with change management procedures.
• Instructions on how to react to alarms must be specified. The reason for the alarm and the subsequent procedures should be documented. The number of alarms should be monitored and the reasons for recurring alarms should be addressed.

Investigation report abstract (pdf, 90 kb)

Further information:

• Taimo Tihinen, Chairman of the Investigation Team, tel. +358 29 5052 423
• Anne-Mari Lähde, Chief Engineer, tel. +358 29 5052 362
• [email protected]

Tukes supervises large-scale industrial handling and storage of hazardous chemicals and mine safety in Finland, among other supervisory duties and tasks.