70
December
2014
HYDROCARBON
ENGINEERING
management, sharing learning etc. it is highly likely that
new risks will arise between periodic reHAZOP studies. So
reHAZOP acts as a necessary ‘safety net’ to catch new
risks. Experience shows that the studies always find new
risks, often significant ones.
On top of identifying new risks as they arise a further
area of good practice is to update the original HAZOP
record to create an ‘evergreen’ risk assessment that
provides the live view of operating risks. This evergreen
record makes future reHAZOPs and other safety reviews,
such as thorough reviews of offshore safety cases, much
more efficient as the information is readily available for
review.
Expected outcomes from
HAZOPs
The purpose of a HAZOP is to identify hazards, not to
engineer solutions. An effective HAZOP team will focus
on addressing the hazards and not try to design the
solution to the problems identified.
Best practice suggests that HAZOP recommendations,
as well as being risk ranked, should be classified with the
expected outcome. There are two main reasons for this:
to assess the potential resource requirement to close out
these actions; and to assist in prioritising. As an example,
simple updates of operating procedures may require
minimal effort for significant gains in risk reduction.
ABB Consulting generally uses nine categories to
classify HAZOP recommendations:
n
n
Information need.
n
n
Procedure review/update.
n
n
Design check.
n
n
Hardware changes including instrumentation.
n
n
Safety integrity level (SIL) determination.
n
n
Maintenance procedures, inspection and testing.
n
n
Risk assessment or specialist review.
n
n
Piping and instrumentation diagram (P&ID) check/
update.
n
n
Training.
For the purposes of this article and the ease of
comparison with the final outcomes, the expected
outcome from the HAZOP team recommendations have
been allocated against one of four categories:
clarification study, design review, documentation check/
update and modification required.
A typical spread of recommendations, against the
above classification, can be seen in Figure 1.
Outcome from
recommendations
With reference to Figure 1, the review of actual outcomes
(i.e. after completing study recommendations), compared
with expected outcomes, initially identified that a
reasonable number of recommendations (10%) had
actually been rejected.
There are legitimate reasons why a HAZOP
recommendation may subsequently be rejected, the analysis
may contain material factual errors, the recommendation may
not be necessary to protect personnel, or the equipment may
be out of service.
In order to better understand the impacts of the
actual outcomes, from implementing recommendations,
these outcomes have been allocated against one of six
categories as follows:
n
n
Document updates.
n
n
Major modification: hardware change, outage
requirement, pressure relief verification.
n
n
Minor modification: set point changes, field tagging,
minor repair.
n
n
Procedural changes.
n
n
Rejected.
n
n
No further action required.
A typical distribution of recommendations, against
this classification, can be seen in Figure 2.
From Figure 2 one can see that half of the originally
recommended actions ultimately required further work
to close out the action. The other half were closed out
with no further work required. The major benefit
resulting from this category will be an increased
awareness and understanding by the operations team and
HAZOP team members who raised the concern in the first
instance.
Notably, approximately 31% of the original
recommended actions resulted in the need for
modifications, of which approximately 19% were major.
The percentage of recommendations actually
resulting in document upgrades was the same (7%) as
predicted by the HAZOP team, however, the actual
distribution of these was different from expected.
Conclusion
Based on this analysis one can see that significant effort
is involved both in carrying out a HAZOP and then
subsequently closing out all arising actions. Also, 50% of
the recommended actions required further work before
they could be closed out.
The benefits of reHAZOP studies are illustrated by the
identification of significant numbers of new hazards.
These new hazards arise for a variety of explanations, all
of which occur frequently in the hazardous process
industries.
It is important to note that the risks identified during
HAZOPs are not reduced until the action is ultimately
closed out.
Further benefits from HAZOPs include an increased
general awareness of the process safety aspects of the
facility, which is beneficial when assessing future
modifications or incident investigations and in support of
regulatory compliance.
References
1. BS IEC61882:2001, Hazard and operability studies –
Application Guide.
2. IChemE, HAZOP Guide to Best Practice 2nd Edition.
3. USA Occupational Safety & Health Admi
ni
stration Standard
1910.119, Process safety management of highly hazardous
chemicals.
