Why hazard analysis?
Meera Nair finds out more
about one of the popular
methods - HAZOP (Hazard
and Operability study),
which is recognised
throughout the world as a
powerful hazard
identification technique
that can be applied to
industries handling
dangerous material
In 1984, the world was shocked
by the industrial disaster in
Bhopal, India, when the
accidental release of deadly methyl
isocyanate killed more than 2,500
people and injured over 200,000.
The fire and explosion catastrophe
in Mexico City is another example,
which killed more than 500
persons.Measures to prevent
major industrial accidents are
necessary not only in highly
industrialised countries but also in
countries where the infrastructure
to prevent and control them has
not been adequately developed.
Preparing a safety case
For most safety-critical systems, it
is not sufficient to build a safe
system; the system must be shown
to be safe. This generally involves
the preparation of some sort of
safety case and a process of
certification with a licensing
authority. The ability to assess the
safety of a system, from initial
identification of potential hazards
through to detailed evaluation of
the safety of an implementation, is
an essential prerequisite for
development and certification.
Universities today, offer courses
which address the issues of hazard
analysis and safety assessment,
presenting both `tried and tested'
methods currently employed in a
variety of industries and novel
concepts and techniques
developed in the latest research.
The courses also take a `whole
lifecycle' approach, emphasising
the integration of safety
assessment at all stages of system
specification and implementation.
The Hazard and Operability study
HAZOP as it is popularly known is
used in the petro-chemical,
offshore and other process
industries to identify and designout
hazards during the design
phase. It is really a structured
brain-storming session. A team is
gathered consisting of key
disciplines (electrical engineer,
process engineer, operator, safety
engineer etc - depending on the
system being 'HAZOP'ed'. A
HAZOP chairman or 'facilitator'
runs the session. The session is
based on a set of 'guide words'
('greater than', 'less than', 'more
than', 'none', etc. etc.) and a list of
parameters ('temperature',
'pressure', 'flow' etc.) then for each
section of the process (called
Nodes) all permutations of guide
words with parameters are
considered. For Example 'In the
separator vessel, what would
happen if the 'flow' was 'greater
than' 'x'?
By running through all
permutations of problems on all
sections of the process, the
assumption is that most potential
problems will be identified (and
designed-out or mitigated).
However the popular consensus
on this technique is that, it is a
very useful technique but it is
not perfect.
HAZOP is recognised
throughout the world as a
powerful hazard identification
technique that can be applied to
both new and existing processes.
Its use is now standard in
industries handling hazardous
materials. However, a major benefit
of HAZOP is the identification of
potential operational problems
....CONTD
