United States United States
Environmental Protection Occupational Safety and
Agency Health Administration
EPA 550-F-15-003 June 2015
Chemical Safety Alert:
Safer Technology and Alternatives
Introduction
The Environmental Protection Agency (EPA) and the Occupational Safety and Health
Administration (OSHA) (EPA/OSHA) issue this Chemical Safety Alert as part of an
ongoing federal effort to improve chemical risk management, advance safety and
protect human health and the environment.1 Recent catastrophic chemical facility
incidents in the United States prompted the President to issue Executive Order (EO)
13650 - Improving Chemical Facility Safety and Security on August 1, 2013. Feedback
from industry, workers, community members and environmental organizations
emphasized the benefits of implementing safer technologies, including those, where
possible, that are inherently safer, as part of an integrated approach to reducing risks
associated with hazardous chemicals.
This Alert is one of several actions discussed in the May 2014 Report to the President -
Executive Order 13650 - Actions to Improve Chemical Facility Safety and Security, on
promoting the use of safer technologies. In the Report to the President, EPA/OSHA
committed to issuing this Alert. EPA/OSHA also committed to developing voluntary
guidance for facility owners and operators that will offer a more thorough examination of
alternative measures and safety techniques and how these might be applied to existing
processes to further reduce chemical and process risks. This Alert is intended to
introduce safer technology concepts and general approaches and establish the risk
management framework for the planned guidance document. The guidance will offer
more practical details and examples. Also, as mentioned in the Report to the President,
EPA and OSHA will not specify technology, design, or process selection for chemical
facility owners or operators.
This Alert explains the concepts and principles and gives brief examples of the
integration of safer technologies into facility risk management activities. Sources of
information on process hazard analysis and inherently safer approaches to process
safety are provided.
1 The statements in this document are intended as guidance only. This document does not substitute for EPA and
OSHA statutes or regulations, nor is it a regulation itself. It cannot and does not impose legally binding requirements
on the agencies, states, or the regulated community, and the measures it describes may not apply to a given situation
based upon the specific circumstances involved. This guidance does not represent final agency action and may
change in the future.
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Chemical Safety Alert - Safer Technology and Alternatives
June 2015
What Does "Safer Technology and Alternatives" Mean?
Safer technology and alternatives means the integration of a variety of risk reduction or
risk management strategies that work toward making a facility and its chemical
processes as safe as possible. Usually these strategies are applied to a chemical
process throughout its life cycle: from initial process and facility design, through initial
startup, to on-going operations. Development usually starts with a systematic hazard
identification using process hazards analysis
(PHA) tools like "What If or "HAZOP" (see
2008 CCPS). These tools work to identify
and assess chemical and process hazards.
Follow-on activities develop, refine, and
implement a hierarchy of hazard controls and
safeguards (see below) to reduce risks.
Hazard Identification and
Process Hazard Analysis (PHA)
First and foremost, you should
thoroughly know and understand ALL
of the hazards of the chemicals
present at your site (e.g., toxicity,
flammability, vapor pressure,
reactivity).
Next, you should thoroughly know and
understand ALL of the hazards
associated with how you process or
handle those chemicals (e.g., what
happens when the power goes off,
what happens when a tank overfills).
Armed with this information, you can now
figure out the best ways to manage these
hazards to prevent chemical incidents!
The first choice for managing chemical
hazards and risks is the use of Inherently
Safer Technology (1ST) or Inherently Safer
Design (ISO). 1ST and ISO are recognized
approaches embraced by chemical process
designers that are most effectively and
powerfully applied at the process design
stage. But they are increasingly applied by
process operators to existing chemical
processes.
What is the "Hierarchy of Controls"?
The various chemical and process hazards present in a chemical facility are managed
using a range of controls and safeguards. For example, properly designed and
maintained vessels, pipes, valves, and temperature and pressure instruments are
needed to safely store a toxic gas liquefied by pressure. The kinds of controls for
managing chemical and process hazards range from "inherent" to various layers of
"add-on" protections. Process safety experts generally prefer using the following
"Hierarchy of Controls" to manage chemical and process hazards:
1. Inherent: The first preference is to avoid hazards by using non- or less-
hazardous substances or materials (e.g., water may be inherently safer than an
alcohol used as a solvent in a particular process), minimizing the quantity of
hazardous substances, or simplifying or moderating process conditions to
eliminate or reduce the likelihood or severity of incidents. Although this approach
is best applied at the process design stage, there may be opportunities as
described below for existing chemical operations;
2. Passive: Protective hardware or structures added on to a process that provide
a risk reduction benefit with no action required by personnel and no motive power
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Chemical Safety Alert - Safer Technology and Alternatives
June 2015
or energy source required (e.g., secondary containment such as dikes and
sumps; blast barriers and shrapnel shields; pressure vessel vent rupture disks;
tank vent flame arresters);
3. Active: Safety features or engineering controls added on to a process that
require active operation of equipment to prevent or mitigate safety hazards (e.g.,
process control devices such as flow control valves and pressure sensors,
temperature, pressure and flow alarms, control interlocks (e.g. a vessel high level
alarm triggers a flow valve to close), emergency shutdown systems, vent and
relief valve scrubbers, vapor suppression systems, de-inventory systems that
require pumps); and
4. Procedural: Administrative systems that mandate maintaining safe process
conditions, operating procedures defining safe operating modes and the steps to
be followed to maintain those modes, training, emergency response procedures,
emergency warning and evacuation procedures.
What are Inherently Safer Approaches?
As noted above, it is preferable to avoid hazards in the first place. "What you don't have,
can't leak." (Trevor Kletz, University of Loughborough, UK). Here, in order of desirability,
are four inherently safer approaches designed to avoid or reduce chemical and process
hazards and brief examples that illustrate how they can be implemented:
Inherently Safer
Approach
Examples
1. Substitution
Use non-or less-
hazardous materials,
chemistry, and
processes. This
approach can
potentially eliminate
the underlying
hazard.
Replace a hazardous material with a less hazardous one:
* Replace gaseous chlorine with hypochlorite
Replace anhydrous gases stored under pressure (e.g., hydrogen fluoride and
hydrogen chloride) with acid solutions (e.g., hydrofluoric acid and hydrochloric
acid) that have a lower vapor pressure
Replace a flammable solvent with a water-based system
Processes that reduce or eliminate a hazard:
* Eliminate bulk oleum and sulfur trioxide storage by using sulfur burning
equipment onsite
Convert anhydrous ammonia refrigeration system to a system that uses a
less toxic refrigerant (e.g., glycol and ammonia) or an ammonia solution
2. Minimization
Use smaller
quantities of
hazardous materials;
reduce the size of
equipment operating
under hazardous
conditions such as
high temperature or
pressure.
Reduce hazardous material inventory in process:
* Use pipe or loop reactors vs. batch vessels
Use continuously stirred, flow-through systems vs. batch reactor vessels
Adjust reactant ingredient quantities to minimize runaway reaction magnitude.
Reduce quantity of hazardous substances stored as feed or product
inventory:
* Implement "produce to consume" processes (e.g., eliminate storage of
chlorine gas by generating chlorine and consuming it as it is produced)
Generate feedstock on-site at the consumer location
Implement "just-in-time" deliveries of feed or product (e.g., use of 100-150
pound cylinders instead of 1-ton containers to supply a process)
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Chemical Safety Alert - Safer Technology and Alternatives
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3. Moderation
Reduce hazards by
dilution, refrigeration,
or process
alternatives that
operate at less-
hazardous
conditions.
Operation at conditions that reduce the potential for and magnitude of
vapor release in the event a leak occurs:
* Reduce temperature or pressure at which a process operates
Use a semi-batch reactor rather than a batch reactor to reduce peak
temperature/pressure in a runaway reaction scenario
Store gas as a refrigerated liquid in a low pressure vessel instead of at
ambient temperature in a pressure vessel
4. Simplification
Eliminate
unnecessary
process or
chemistry
complexity to reduce
the likelihood of
controls and
safeguards failing to
operate properly on
demand.
Standardize equipment and/or control systems to simplify operator training
and operations to reduce the potential for human errors
Reduce the number of process vessels or other components handling
hazardous materials
Reduce the number of interconnections to reactors to minimize inadvertent
flow paths
Use fully welded construction to eliminate/minimize the potential for flange
leaks
Locate pipelines to minimize collision impact
Minimize the length of hazardous material piping runs; eliminate "dead legs"
Eliminate situations where rapid operator intervention is required to prevent
accidents or spills
What Should You Do First?
1. Know Your Chemicals
Your first step should be to thoroughly know and understand ALL of the
physical and chemical properties of the substances present on your site. Is the
chemical volatile? Is it toxic? Will it generate a dense gas cloud if it gets
released? What happens if it is accidentally mixed with water or something
else handled at the site? Is if flammable? What happens if there's a fire?
2. Know Your Processes
Next, thoroughly know and understand ALL of the hazards of the ways in
which the substances at your site are handled and/or processed, including
those that just temporarily sit in a warehouse. What happens if the power goes
off? What happens if a storage tank overfills? What happens if the temperature
rises in the reactor? What happens if the compressor generates too much
pressure? What if there's a fire? What happens if a forklift punctures the
container?
There are many tools to help you gather and understand chemical and process hazards
such as "What If?" and "HAZOP." These tools help you step through the many ways
things can go wrong and to understand the potential consequences when something
does go wrong (see CCPS 2008).
Armed with this information, now you can figure out ways to manage and control these
hazards and to reduce risks as low as possible.
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Chemical Safety Alert - Safer Technology and Alternatives
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What are Some Approaches to Safety / Risk Management?
Here is a flow chart you can use to take steps to find ways to address the chemical and
process hazards you identified above. Please note: there is no "silver bullet" or "one
size-fits-all" solution. You may not be able to eliminate all chemical and process
hazards. In some cases, there may not be practical inherently safer alternatives, and in
other situations, an inherently safer approach will only reduce part of the potential risk
associated with the use of a hazardous material or process. You may find you need to
use multiple "layers of protection" (see below) at various points to make your site safer.
At each point in this flow chart, you should examine whether any of the alternative
opportunities you might choose is achievable, practical and cost effective and that it
doesn't inadvertently transfer risks elsewhere that could either be unmanaged or less
desirable. For example, reducing chemical inventory too low could trigger the need for
more frequent supplier shipments at odd hours, increasing the potential for a release
during transfer operations.
Inherent
What hazards can be
avoided?
Passive Layers of
Protection
Active Layers of
Protection
Substitute
Can other chemicals be
used? Can process be
changed?
Minimize
Can the amount of
chemical be reduced?
Simplify
Can the process be
streamlined?
Moderate
Can conditions be
changed?
Procedural Layers of
Protection
Figure 1
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Chemical Safety Alert - Safer Technology and Alternatives
June 2015
What are "Layers of Protection"?
The hierarchy of controls concept helps classify safeguards by their reliability, with
inherently safer approaches generally being highly reliable while administrative
safeguards tend to be less reliable in preventing harm. However, controlling risk almost
always requires using multiple approaches. The concept of layers of protection
acknowledges that individual safeguards are not totally reliable or effective, and thus
multiple safeguards ("layers") may be needed to minimize the chances of an initial fault
propagating to a full blown incident with potential for harm. This is often illustrated using
the "Swiss Cheese" model for incidents (see Figure 2). In this model, each safeguard
layer has the potential to fail, with highly reliable safeguards (e.g., "inherent" ones)
having relatively few
"holes", and less reliable »Swiss cheese" Incident Model
safeguards (e.g.,
"procedural") having
more. While no single
layer can adequately
control the hazard,
having a sufficient
number of adequately
reliable safeguards can
greatly reduce the
chance of all of the
"holes" lining up so that
an incident actually
occurs.
More Reliable
Safeguard
Gaps/Failures
Initiating
Event
\
Less Reliable
Incident!
Safeguards
(Protection Layers)
Figure 2
Facilities typically utilize as many layers as necessary to adequately control their
process hazards, with preference given to more reliable safeguards. Thus an
atmospheric storage tank containing a highly hazardous chemical might contain the
minimum amount of material needed for the process to operate reliably (inherent -
minimization), have secondary containment provisions (passive), use multiple level
alarms and controls to detect and react to potential overfills (active), and utilize
operating and maintenance procedures to reduce the likelihood of an overfill or leak
occurring and to ensure that safeguards operate properly when called upon. By
ensuring that an adequate number of reliable safeguards are in place and functional,
the facility can confidently manage the risks associated with the storage tank.
What's Next?
As noted above, this Alert is designed to introduce approaches and concepts
associated with safer technology and alternatives; future guidance will offer more
practical details and examples. In the meantime, you can certainly start to learn more
about process hazards analysis (see 2008 CCPS), the hierarchy of controls and layers
of protection. The second edition of the Center for Chemical Process Safety (see 2009
CCPS) guideline document Inherently Safer Chemical Processes - A Life Cycle
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Chemical Safety Alert - Safer Technology and Alternatives
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Approach (CCPS 2009) is one of the most detailed references, with numerous
examples and case studies related to inherently safer applications. More recent
publications continue to contribute new ideas, tools, and examples in the inherently
safer arena (See Appendix A).
Ultimately, it is up to you to understand your facility's risks and what you need to do to
protect your workers, the public, the environment and your capital assets. As described
in the CCPS "Business Case for Process Safety" (see
http://www.aiche.org/ccps/about/business-case) diligence by owners and operators to
adopt good process safety management practices and to do things the right way, every
day, enjoy the positive benefits of better operations and continuous improvement.
Finally, the various agencies involved in chemical safety and security are working with
industry to collect, develop and publicize best practices, including approaches for
consideration of inherently safer alternatives to existing controls and safeguards (see
https://www. osha.gov/chemicalexecutiveorder/LLIS/index.html).
Appendix A - References
Reference
1978Kletz
1985Kletz
2008 CCPS
2009 CCPS
2010 CCPS
OSHA
2012 Hendershot
Bibliography
Trevor Kletz, "What You Don't Have, Can't Leak," Chemistry and
Industry, (May 6, 1978).
Trevor Kletz, "Inherently Safer Plants," Plant Operations Progress,
(New York: American Institute of Chemical Engineers, 1985).
Center for Chemical Process Safety, American Institute of Chemical
Engineers, Guidelines for Hazard Evaluation Procedures, Third
Edition (New York: John Wiley & Sons, 2008).
Center For Chemical Process Safety, American Institute of Chemical
Engineers, Inherently Safer Chemical Processes - A Life Cycle
Approach, Second Edition (New York: John Wiley & Sons, 2009).
Center for Chemical Process Safety, The American Institute of
Chemical Engineers, Final Report: Definition for Inherently Safer
Technology in Production, Transportation, Storage, and Use, (July
2010),
http://www.aiche.org/ccps/documents/definition-inherently-safer-technology
"Transitioning to Safer Chemicals: A Toolkit for Employers and
Workers," https://www. osha.gov/dsg/safer chemicals/index, htm I
Dennis C. Hendershot, "Inherently Safer Design: The Fundamentals,
Chemical Engineering Progress (January 2012),
http://www.aiche.org/resources/publications/cep/2012/ianuarv/inherently-
safer-design-fundamentals
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