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


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.

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,
                                                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

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

   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
1. Substitution
  Use non-or less-
  hazardous materials,
  chemistry, and
  processes. This
  approach can
  potentially eliminate
  the underlying
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
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
*  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)	

   Chemical Safety Alert - Safer Technology and Alternatives
                                                        June 2015
3. Moderation
  Reduce hazards by
  dilution, refrigeration,
  or process
  alternatives that
  operate at less-
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
  process or
  complexity to reduce
  the likelihood of
  controls and
  safeguards failing to
  operate properly on
   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
   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
  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.

Chemical Safety Alert - Safer Technology and Alternatives
                                      June 2015
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.
   What hazards can be
     Passive Layers of
     Active Layers of
                                 Can other chemicals be
                                 used? Can process be
                        Can the amount of
                        chemical be reduced?
                                  Can the process be
                         Can conditions be
Procedural Layers of
                                   Figure 1

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
       More Reliable
              Less Reliable
        (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

Chemical Safety Alert - Safer Technology and Alternatives
June 2015
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
2008 CCPS
2009 CCPS
2010 CCPS
2012 Hendershot
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
"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),