During routine startup of a chemical reactor an
overpressure occurred that resulted in a steam release
and severe burn injuries to the operator.
Several potential root causes for the release were
An OHSA investigator had concluded that the steam was
produced due to the heat of mixing of purge water
with sulfuric acid that had not been flushed from the
reactor after the last batch production.
According to this theory, the chemical manufacturer was responsible for causing the accident.
However, our thermodynamic analysis demonstrated that
it would not have been possible for the heat of mixing
to generate the steam. In fact, this scenario would
have resulted in temperatures no higher
Our investigation discovered that an outside contractor
had improperly connected a process line to a heat exchanger
during scheduled routine maintenance. This resulted in
one of the reactants being introduced to the reactor at
an elevated temperature. Thus, the outside contractor
(not the chemical manufacturer)
was responsible for the root cause of the accident.