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Case No.5

Chemical burns to skin by contact with high-concentration raw liquid phenol while taking countermeasures against abnormal reactions in the synthesizing reaction process for phenol  

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[Circumstances of Incident]

This accident occurred in a phenol resin manufacturing plant, where the phenol resin synthesis process included: mixing raw phenol with acid in a reaction vessel; adding formalin while heating the raw material; and adding denaturant prior to completing the reaction process by steam heating. Phenol resin is then produced by dehydration.

A team consisting of a supervisor and four workers was scheduled to work from 11:00 in the evening to 8 o'clock the next morning. Trouble occurred during phenol reaction process. As temperatures in the reaction vessel rose to an excessive level due to operational mistakes by workers, cooling operations were started. However, other mistakes in the cooling process resulted in foam resin (an intermediate product) adhering to pipes and a wide range of other equipment. Although the foam resin was removed, there was another serious mistake by the supervisor. When the supervisor ordered the cover of a check valve to be opened for cleaning at around 10:30 in the morning, dehydration liquid spouted from the valve. Four workers who were engaged in this emergency operation were injured when their skin was burned by the high-concentration phenol.  


The direct causes of this accident may be attributed to the supervisor's erroneous instructions to clean the check valve instead of cleaning a strainer contaminated by foam resin due to trouble during the phenol resin synthesis process. Dehydration liquid containing high-density phenol spouting from the valve injured four workers

Although the supervisor and four workers knew about the presence of the check valve, but had no knowledge of its structure and functions. This is why they mistook the valve as the strainer.
Moreover, while workers were wearing protective masks and rubber gloves, their clothing was made of cotton rather than impermeable protective fabric. As a result, they sustained injuries on their necks, bodies, arms and legs.

The indirect causes of this accident relate to the following:
(1) An instruction book covering this operation indicated no clear instructions on vacuum adjustments, leading to rapid increases in the temperatures in the reaction vessel due to a worker's erroneous operations. Thus vacuum cooling is required to correct the situation.
(2) When proceeding with the vacuum cooling, workers mistakenly switched over to "dehydration piping" as they normally do during the resin transport process, thus requiring the cleaning of the strainer and other equipment.

[Type of business] Inorganic/organic chemicals manufacturing
[Type of accident] Contact with hazardous substances, etc.
[Number of victims]Four injured (involving absence from work)