| The Center for Chemical Process
Safety, an industry-sponsored organization affiliated with the American
Institute of Chemical Engineers, offers this useful guidance in its
publication, Guidelines for Technical Management of Chemical Process Safety
(1989):
In any operation, situations will arise that were not foreseen when the
operating procedures were developed. At such times, personnel may want to
conduct operations in a way that differs from, or contradicts, the process
technology or the standard operating procedures.
To assure that these deviations from normal practice do not create
unacceptable risks, it is important to have a variance procedure, or to have
incorporated the same means of control into other management systems. The
variance procedure will require review of the planned deviation, and
acceptance of the risks it poses. The variance procedure should require
- the explanation of the deviation planned;
- the reasons it is necessary;
- the safety, health, and environmental considerations;
- control measures to be taken;
- and duration of the variance.
Variances should require the approval by a suitable level of management,
based on the process risks involved. Also, they should be documented to
assure consistent understanding by all affected individuals and departments
of what specific departure from normal practice is to be allowed.
A formal hazard analysis may be appropriate depending on the complexity
of the change or variance. A hazard analysis for the Equilon situation would
have likely determined the limitations of the temperature readings and that
it was unsafe to open the drum. It would have also identified the possible
release of a large volume of very hot liquid as a significant risk |
"To assure that
deviations from normal practice do not create unacceptable risks, it is
important to have a variance procedure, or to have incorporated the same
means of control into other management systems.”
|
