che_december-2024 - 36

present, people present
❍
❍
Delayed ignition case, people
may be present
Immediate ignition gas, people
may be present
Step 3 - How likely is it to occur
in the absence of safeguarding? If
in doubt, " go big or go home " and
assume an occurrence of an event
taking place anywhere from once per
year to about once every 10 years.
For the compressed-gas cylinder example,
we will assume a leak from a
faulty gas-cylinder valve connection
with people present and absolutely
no safeguarding in place. Note, the
proviso of " in the absence of administrative
and engineering safeguards "
is a requirement for a number
of best practices, such as those
required by the U.S. Dept. of Labor's
standard, OSHA CFR 29 1910.119
- Process Safety Management of
Highly Hazardous Chemicals, and
is used so that safeguards are not
credited more than once, and that
the focus is on the worst case, not
the most likely, less harmful case.
This legislation contains requirements
for preventing or minimizing
the consequences of catastrophic
releases of toxic, reactive, flammable
or explosive chemicals. These
releases may result in toxic, fire or
explosion hazards.
Should an LOPC occur with people
present, and there is no gas detector
available, no odorant in use
and no ventilation, then as according
to the SDS, without ignition, the
released methane could displace
the air in the room and the oxygen
concentration could be reduced
below 19.5 vol. %, compared to
a normal concentration of about
21 vol. %, which could then result
in the asphyxiation of any and all
people present during the time of
the release.
Step 4 - What are the consequences
that could occur for
all risk receptors? These consequences
may include adverse impact
on people (loss of life, injury
or illness), the environment (harm
to air, water and soil, both on and
off the physical site) and finances
(damage to property or assets,
loss of revenue or negative reputational
impact). Some potential risk
outcomes are listed below for the
compressed-gas cylinder hazard
36
scenario:
* Asphyxiation - Fatalities and
equipment damage, as well as production
outages and potential environmental
release
* Flash fire - Fatalities or burns
and equipment damage
* Explosion - Fatalities and
equipment damage
* Jet fire - Fatalities or burns and
equipment damage
Step 5 - What is the level of risk
in the absence of safeguards?
Note, to confirm all of the below
considerations for the risk receptors,
it is necessary to fully develop
an approved corporate risk assessment
matrix (RAM).
* Safety - High, unacceptable
without safeguards
* Environment - Low, unacceptable
without Safeguards, regardless
of the risk
* Economics - Medium, unacceptable
without
safeguards,
regardless
of the risk
* Reputational risk - Cannot be
developed without corporate guidance
via an approved RAM.
Step 6 - What can you do to
eliminate or mitigate the harm
and reduce the level of risk?
Below
are
some
recommended
practices to address the hazard
and risk associated with the compressed-gas-cylinder
scenario.
* Develop operating and maintenance
procedures, complete with
training
* Use gas only with odorant
* Move any burn to an inherently
safe location, like outside of
the building
* Control access to the area
* Employ gas detection and appropriate
heating, ventilation and air
conditioning (HVAC) systems
* Explore the potential use of nonfired
equipment
* Specify flame-resistant PPE
* Check for leaks and pressuretest
all equipment prior to use
* Explore the use of a burner
management system (BMS)
Step 7 - How much will it cost to
achieve significant and realistic
safeguarding? This cost should look
at not only financial resources, but
also employee time and effort, to determine
if the cost will be proportional
or disproportional to the reduced
level of risk. For example, if it will cost
$1 million to mitigate a risk that is only
costing $10,000, is this recommendation
a valid one for the organization
to undertake? Or, alternatively, if the
mitigation requires a number of team
meetings and expenses to design,
acquire, install and maintain, and the
likelihood and the consequences do
not change, is the of value to your
organization to adopt even more
work of low, or questionable value?
Below are some specific questions
to consider.
* How much will it cost to reduce
your risk from High/Unacceptable
to Medium/Acceptable with safeguards,
or even to Low Risk?
* Will the costs to achieve
an acceptable level of risk be
within budget? If so, and management
approves and supports
your review, then you can
begin establishing an " As Low as
Reasonably Practicable " (ALARP) assessment
on your hazard reviews and
analysis procedures.
■
Edited by Mary Page Bailey
References
1. Center for Chemical Process Safety (CCPS) " Guidelines
for Hazard Evaluation Procedures, " American
Institute of Chemical Engineers (AIChE), 3rd Ed.,
April 2008.
2. Pitblado, R. and Turney, R., " Risk Assessment in the
Process Industries, " IChemE, February 1996.
3. Crowl, D. A. and Louvar, J. F., " Chemical Process
Safety: Fundamentals with Applications, " Prentice
Hall, 3rd Ed., January 2011.
4. U.K. Health & Safety Executive, Managing risks and
risk assessment at work, https://www.hse.gov.uk/
simple-health-safety/risk/print.htm.
5. R. E. Knowlton, " An Introduction to Hazard and Operability
Studies - The Guide Word Approach, " Chemetics
International Co., 1992.
6. U.S. Dept. of Labor, OSHA 29 CFR 1910.119, Process
Safety Management of Highly Hazardous
Chemicals, Sept. 2014.
Author
Bill Timbers, P.E., P.Eng. is an
engineering consultant specializing
in risk management,
safety management,
process
operational
excellence and business consulting
(Email:
bill@timbersconsulting.
com). He holds degrees in chemical
engineering and applied
chemistry, and has completed advanced
graduate studies related
to risk and occupational health and safety at the University
of Alberta, the University of Houston and the London
School of Economics. Timbers is a registered professional
engineer in both Texas and Alberta, and has
worked for many years in the chemical industry in project
management and production and process
engineering roles.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
DECEMBER 2024
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