This incident occurred at Flixborough, U.K., and involved a plant manufacturing caprolactum, with cyclohexane as one of its raw materials. The incident occurred during noon hours, on 1 June, 1974, a saturday (which was a half working day) and it is due to this reason that there were very few people on site. One of a series of reactors for cyclohexane had been taken out for repairs, and a makeshift connection had been provided in its place. This makeshift bypass pipe could not withstand the high pressures it was subjected to, and quickly failed, allowing boiling cyclohexane to release into the atmosphere. It is believed that about 125 tonnes leaked out, and as the liquid was already boiling, it immediately flashed to vapour. A large vapour cloud of approximately 40 tonnes of cyclohexane formed, and soon ignited (the exact source of ignition is not clear). The resultant explosion resulted in large scale damage to the works, a large number of secondary fires, and the death of approximately 28 people. One of the most important effects of this incident was that the effects of the explosion were felt in adjacent neighbourhoods, causing serious injuries and property losses.

The damage was intense in the works, and ultimately affected around 15 acres of the site. Fires were severe, and affected large stocks of flammable liquids, in the storage area. The initial explosion also damaged the fire water system, rendering it unusable.

At its peak, the firefighting operation involved more than 50 fire tenders, and more than 200 personnel. The last fires were finally put out after around 11 days.

Flixborough Disaster-effects and consequent safety upgradation

The Flixborough Disaster became synonymous with the fallout of the industrial activity, and brought to the fore, the immense destructive effects of flammable chemicals. The other important effect of this incident was that it also affected the nearby communities, which till then believed that they were in no way concerned with what goes on in these industrial premises. However, with this incident the world became rudely aware of the fact that incidents in the industry were capable of causing damage to community, outside its premises also. This had a very important bearing on the future of industrial activity, as some major changes were effected after this incident.

The sheer destructive power of a vapour cloud explosion was witnessed for the first time by the industrial world and the loss of 28 lives, a very high number for most developed nations, was viewed very seriously by the authorities. Primarily, it forced industry personnel to carefully re-evaluate the properties of the different chemicals being handled in industrial premises, and the processes in which they were involved. Risk analyses of industrial activities began to be carried out in earnest, and it became mandatory under law to carry out such studies before the setting up and during operation of industries. As the incident was precipitated by probably a 'not too well thought out' modification in the plant, it also brought about stricter operating and maintenance procedures and practices. For the first time, industries began setting up 'Off- site' Disaster plans in conjunction with civic authorities, to take care of possible effects of incidents on neighbouring communities. Most commonwealth countries were affected by this incident, and as the standards and codes of these countries are also based on Britain's, they too modified and incorporated these changes to ensure better industrial safety.