The Weekly Reflektion 42/2023

Normalisation of deviance in some form has been around for a long time, however the terminology became well known through Diane Vaughan’s studies on the space shuttle Challenger disaster in 1986. Normalisation of deviance is particularly dangerous when practices that have a potential to be deadly, become established at a facility or in an organisation. Normalisation means these practices are accepted and unless someone speaks up and gets them stopped, they continue until an incident, accident or disaster occurs. Some companies become aware of the dangers of such practices before someone is hurt. Others are not so lucky.

Do you have practices that could turn out to be fatal?

June 9th, 2009 at the Conagra Slim Jim Plant near Garner,North Carolina, there was a catastrophic explosion that resulted in the deaths of 3 people and injured 71. Febuary 7th, 2010 at the Kleen Energy Power Plant in Middleton, Connecticut, there was a devasting explosion that killed 6 people and injured 50. Two deadly blasts 8 months and hundreds of miles apart. The tragic accidents at these two plants had the same cause. Both incidents involved the practice of using natural gas to flush through pipework to clean out debris or to remove air before the pipework is taken into service. 

In this Reflektion we will look at the Conagra Slim Jim plant explosion. The accident occurred during the commisioning of a new gas-fired industrial water heater. A newly installed pipe(the blue pipe in the figure above) that supplied the heater, had been leak tested with air and the air was to be removed before start up. The operator purged through the original pipe (the grey pipe in the figure) to an outside location. The new pipe was however still full of air. The operator then opened a valve at the heater and started to purge air out of the pipe with natural gas. This vented gas into the enclosed area around the heater. There were no specific requirements on routing the gas to a safe location. After a while the operator tried to start the heater and was unsuccessful. He believed there was still air in the pipe and continued purging and he did not use a gas detector to measure the gas content of the atmosphere. There as no smell that would indicate there was gas coming through the system. Natural gas supplies are normally spiked with mercaptans that give the gas a sulpurous odour to help people detect leaks. Unfortunately new carbon steel pipework adsorbs mercaptans until the surface is saturated. This effect is called ‘odour fade’ and may explain why the operator did not smell any gas even though gas was building up in the area. It is estimated that this the purging continued for two and a half hours and there are indications that the operator was distraced by other tasks. The gas concentration eventually reached the lower explosion limit and ignited. The ignition source was never confirmed although there were several possibilities. The investigation eventually concluded that it was most likely faulty electrical equipment.

Hydrocarbon gas should be contained at all times and should only be intentionally released if there is no viable alternative. In this case the gas must be released to a safe location where an explosive mixture cannot occur. While this may seem obvious, it is obviously not so obvious. 

When deadly practices become normalised then it really is only a matter of time before there is a serious incident and someone gets hurt or killed.  

Reflekt AS