INGENIEUR
storage tank resulting in an escape of unleaded
petrol and the formation of a cloud of flammable
vapour that ignited. The causes which were
uncovered during the investigation highlighted the
failure of multiple levels of protection due to:
●●
inappropriate procedures in testing and
operation,
●●
failure to pass critical design knowledge
down the supply chain of safety systems,
●●
lapses in maintenance and fault reporting,
and
●●
poor interface design.
The initial failures leading to the accident were
a combination of a stressful working environment,
and undocumented filling and handover
procedures. Similar to the Bhopal accident, it was
shown here that major accidents often result from
interaction among components – caused by the
occurrence of a variety of flaws and deficiencies,
together forming a ‘bedding’ for the accident to
happen [7].
The accidents which have been discussed have
to be linked with changes driven by competition,
cost pressure, management methods and
human behaviour. The complexity of the process
installations and technologies are observable but
are not dominant in causing the accidents [7]. The
accidents can be linked to;
●●
poor management,
●●
weak competency,
●●
extreme operating conditions,
●●
focus only on reducing cost and saving time,
but at the same time loss of knowledge and
expertise,
●●
complex safeguarding and control systems,
and
●●
slipping maintenance and unclear
responsibilities,
All these produced conditions in which risk
awareness slowly declined. It can be seen that
due to such scenarios which can be linked to the
complex causation mechanism, process safety
incidents will still happen.
Process Safety Management
Operations supported by multiple layers of
protection may result in increased security for
employees, the public and increased profits. It is
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JUNE 2013
important though to acknowledge that not all the
layers totally cov er the entire potential risk. Each
of the layers has its own weaknesses as previously
mentioned e.g. complex control systems, slipping
maintenance, low reliability of safeguards etc.
However, together, the whole suite of layers offers
a thick blanket of protection. Nonetheless it is
not enough to have these layers of protection
and to design systems to reduce the risks. It is
also important to consider how these layers of
protection and consequent chemical process
safety, can be managed.
The promulgation of 29 CFR 1910.119
Pro c e s s S afe t y M anagement (P SM) of
Highly Hazardous Chemicals Standards by
Occupational Safety and Health (OSHA) US
applies the principles of management systems
to the safety of chemical processes [8]. The
bulk of PSM Standards contains general
requirements which are performance based
and not site - specific. The PSM standard
emphasises the management of hazards
through a comprehensive programme that
integrates technologies, procedures, and
management practices. The standard has
14 elements that are fundamental to running
a safe chemical operation. These include
procedures to;
●●
ensure employee participation,
●●
train employees and contractors,
●●
ensure mechanical integrity of equipment,
●●
manage change procedures,
●●
investigate incidents,
●●
plan for and respond to emergencies,
●●
audit for compliance.
Requirements to establish the PSM on-site
include information on the chemicals, equipment
and technology of the process, hazard analysis,
written operating procedures for the facility, and
detailed documentation of data collected to
assure for mechanical integrity.
The challenge with PSM is that it is not an
easy standard to understand or implement. But
as processes become more complex and the
number of operational conditions to be controlled
becomes more overwhelming, the PSM standards
offer a systematic and structured approach to
identification, prevention, and mitigation of risks
associated with hazardous chemicals to ensure
safe operation.