Fabricated metal products (e.g. ironing board frames and similar) are slung from an overhead chain conveyor and pass through a spray painting booth before entering a narrow and tall oven to bake the paint. The oven operates at a high temperature (100°C).
Occasionally the conveyor system breaks down due to chains missing the cogs which pull it or which guide it around corners etc. This happens about twice a week on average. Maintenance workers are called to fix the problem. They know that it is dangerous (because of heat stress) to enter the confined space of the hot oven and that they should wait until it has cooled down.
After the electric heaters are turned off the oven takes some three hours to cool down to what is
regarded as a reasonable temperature (based on comfort considerations) by the fitters. During
this time of course the production line comes to a complete stop – the whole factory depends on
it. Succumbing to pressures from the production people, the maintenance workers have
developed their own way of dealing with the problem. They put on woollen coveralls, gloves
and hat and quickly slip into the narrow entrance of the oven, having turned the heaters off. In
this way they are often able to quickly assess the reason for the stoppage and correct it before
feeling overcome by the heat. Correction usually involves working with arms above their heads
for minutes at a time (i.e. work on the conveyor chains and cog wheels) with some force being
exerted. Typically, problems are rectified within 15 minutes. When pressed, they admit that
over the last five years (the longest period of employment here of any of them) there have been
‘a couple’ of times when the person doing this work got out of the oven before completing it
because he was feeling overcome by the heat. The factory has been using this production
technology for 12 years and in that time there have been no deaths or serious emergencies
arising from the practice described above. The maintenance workers think this happens about
once a week on average.
Assessed by a safety purist, this is not an acceptable practice. There is no recognition of the
oven as a confined space and none of the required confined space controls are in place. There is
no formal or informal means of keeping in touch with the fitter who is doing the work. The
fitters are not in their youth and there is no real knowledge of their medical condition and how
they might be stressed by the extremely elevated temperatures. If one was to become
unconscious in the oven, either through heat stress or through falling down, some time might
pass before this was recognised. There is then the problem of getting him out – there is only one
suit of clothing and the narrowness of the space would make it hard for others to enter with a
stretcher etc. One can clearly see that this is a death risk.
The proposal is put forward to install a fan and air cooler, which would blow cold air through the
oven and reduce the time taken for the temperature to drop to a reasonable extent from 3 hours
to half a hour. It would, however, take the oven another half hour to get back up to temperature
after the work had been completed.
Because of the size of the oven a sizeable fan and cooler are required. It is estimated that the
cost of installation (wiring, motor, fan, ducting, supporting steelwork, controls, temperature
gauge, cooling system) would be about $125 000. Running and maintenance costs would be
minimal, as the unit would be seldom used and then only for short periods.
The financial manager says that the ‘cost’ of not producing saleable product for short periods is
the loss of profit resulting from having to make up production on overtime, as the factory can
sell all of its output. The sales value of production in the factory is $55000 per day. The profit
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