United States
                Environmental Protection
                Agency	
Office of Solid Waste
and Emergency Response
(5104A)	
EPA 550-F-01-010
September 2001
www. epa. gov/ceppo
&EPA   Chemical  Accidents from  Electric

                Power Outages
 ^ C n pi A!    The Environmental Protection Agency (EPA) is issuing this Alert as part of its ongoing effort to protect human health and
 ^* ™ •          the environment by preventing chemical accidents. EPA is striving to learn the causes and contributing factors associated
                with chemical accidents and to prevent their recurrence. Major chemical accidents cannot be prevented solely through
                regulatory requirements. Rather, understanding the fundamental root causes, widely disseminating the lessons learned,
                and integrating these lessons learned into safe operations are also required. EPA publishes chemical safety Alerts to
                increase awareness of possible hazards. It is important that facilities, SERCs, LEPCs, emergency responders, and others
                review this information and take appropriate steps to minimize risk. This document does not substitute for EPA's
                regulations, nor is it a regulation itself. It cannot and does not impose legally binding requirements on EPA, states, or
                the regulated community, and the measures it describes may not apply to a particular situation based upon circumstances.
                This guidance does not represent final agency action and may change in the future, as appropriate.
                    Problem

                    Power   outages  and  restarts  could
                    potentially  trigger a  serious chemical
                    accident.

                          Electric power outages are often caused
                          by lightning, high wind, or ice storms,
                          as well as accidents at power plants
                    or transmission lines.  Hot weather power
                    demands could trigger rolling blackouts.
                    Although  planned rolling blackouts  can
                    cause process shutdowns or upsets, they are
                    preferable to power system overloads  and
                    failure,  or to low voltage brownouts which
                    can be destructive to electrical equipment.
                    The  recent energy  crisis  in California
                    illustrates the aggravation caused by power
                    outages. Power interruptions at  chemical
                    handling facilities are a particular concern
                    because of the possibility of a  chemical
                    accident.  Incident data from the National
                    Response Center (NRC) shows that during
                    2000 there were about 240 chemical releases
                    reported  due  to  an  electric  power
                    interruption;  only  a few were related to
                    planned rolling blackouts.  A number of
                    releases  were   associated  with  power
                    resumption and restart of operations  (see
                    Table 1).
         Accidents

         One  accident  occurred  when  power was
         interrupted and another during restart after
         power resumption.

         Gramercy, Louisiana, July 1999.  This plant
         converts bauxite to alumina in a series of steam-
         heated pressure vessels. A loss of power stopped
         all pumps including those that circulated process
         material through heat exchangers for cooling.
         However,  steam injection stayed on causing
         temperatures and pressures to increase.  Pressure
         relief valves and piping were blocked or choked
         with solid deposits  hindering their ability to
         relieve the increasing pressure.  Several vessels
         over-pressured and exploded.  The force of the
         explosion and release of highly corrosive caustic
         material injured 29 employees and extensively
         damaged the plant.

         Several  lessons  can  be  learned  from  this
         accident: Process operations must be evaluated
         for the consequences associated with  a  power
         outage to ensure that the process reaches a safe
         condition.   In this  case, if process flow and
         cooling pumps are critical to the safe state of the
         process  when  electric  power is  lost, then a
         backup power supply or steam driven spare or
         backup pumps should be evaluated. In addition,
         interlocks that  stop steam heating upon loss of
         flow or cooling should be considered. Finally,
         pressure relieving systems must be inspected
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CHEMICAL ACCIDENTS FROMELECTRICPOPFER OUTAGES
                                                                                             SEPTEMBER 2001
and maintained to ensure their  ability to function as
intended.

Richmond,  California, May 2001.  This  plant was
running normally when a truck struck a utility pole,
causing a power interruption and total plant shutdown.
Shortly thereafter, sulfur dioxide (SO2) and sulfur trioxide
(SO3) began to escape from a boiler exit flue. When
power was restored a short time later, a steam turbine that
is  required to  keep  the boiler exit flue under  negative
pressure  could   not  be   immediately  restarted.
Troubleshooting revealed that an automatically controlled
governor valve had  malfunctioned  and the turbine was
restarted.   During the time the turbine  could not be
restarted,  residents  near the plant  were  instructed to
remain indoors.  Around 50 to 100 individuals sought
medical attention following the release.

As above,  equipment or procedures critical to safe
shutdown, continued operation, or restart conditions must
be identified, maintained, tested, and kept in a ready-to-
operate state.  The plant installed backup power systems
to keep the steam turbine running through a power outage.
In addition, preventative maintenance on the steam turbine
valves has been enhanced to  ensure that  these valves
operate properly when needed.
  Table 1.  Some chemical release causes reported
  to the NRC during 2000:

  • Fueling pump automatically restarted when
  interrupted power was restored;
  • Power outage during product transfer caused
  tank and secondary containment overflow;
  • Power outage to computer control system during
  startup caused release from pressure relief;
  • Utility company's hot weather power reduction
  caused plant's excessive flaring;
  • Power loss caused shutdown and valves did not
  close;
  • Scheduled power outage caused flaring; and
  • Power outage caused shutdown of pollution
  control device and release of material.
Hazard Identification

Find potential weak spots early or ultimately they will
find you!

When power is lost for any reason, pumps stop pumping,
compressors stop running, stirrers quit mixing, lights go
out, and  instruments  and controls  may  malfunction.
These equipment outages may lead to tank overflows,
runaway chemical  reactions,  temperature  or pressure
increases or decreases, all of which could lead to a spill,
explosion, or fire. Even if there is no immediate release,
there may be a delayed reaction caused by thermal shock
or  other  factors  that  can  compromise  equipment
mechanical integrity during subsequent operation.  When
power is restored even after a brief interruption,  some
equipment may  automatically restart before process
operations are ready while others may need to be reset and
manually restarted.

The first task  is  to  identify and  rank  the process
operations or equipment that pose the most  serious
potential for fire, explosion, or hazardous material release
in the event  of utility interruption.  A good tool that can
help  identify and  rank critical  equipment and the
consequences to the process  upon loss of power is a
formal process hazard analysis (PHA) within a sound
process safety management system (PSM).  For example,
the Hazard and Operability (HazOp) or What-If analysis
techniques coupled with good employee participation is a
particularly  strong  combination for identifying hazards
and failure mechanisms associated with power failure and
restart. These tools and approaches can help you create
a list of process equipment (pumps, valves, instruments)
and to note  exactly what happens to each device  when
power fails or  is  restored.   Don't forget to include
equipment that may be indirectly affected; for example,
pneumatic devices  that  quit  when  air pressure  falls
because  an  electric-powered   compressor   stops.
Equipment  should  "fail-safe;" in other words,  when
electric power or another utility (e.g. air or water) is lost,
the equipment and process   should  come to  a  safe
condition. And when power is restored, devices should
keep the process in a safe condition until it is ready  to
resume normal operations. Table 2 shows an example list
of some devices and possible fail-safe and restored states.
                                                      Be sure to consider power dips, brief interruptions, and
                                                      losses to only some equipment in your hazard evaluation
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CHEMICAL ACCIDENTS FROMELECTRICPOPFER OUTAGES
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as unexpected and unusual circumstances may occur. For
example, some equipment may continue operating while
others trip out.

Most chemical facility operators have developed sound
contingency plans for responding to various types of plant
utility interruptions, including electric power  outages.
After a power failure  is over, evaluate how the process
equipment and people  responded to the situation to
identify hazards and potential negative consequences that
were not previously recognized.  In some cases the type
and magnitude of the disruption that occurred when power
was interrupted was not fully anticipated. In other cases
the problem was caused by adverse actions that took place
when power was restored.  Power failure contingency
plans should be regularly reviewed, updated and tested.
Table 2
Sample Equipment List and Fail-Safe Modes
Device
Reactor Feed
Pump
Reactor Steam
Heat Valve
Cooling Water
Feed Valve
Reactor Vent
Valve
Reactor Mixer
Transfer Pump
Status When
Power Fails:
Off
Closed
Full open
Full open
Off
Off
When Power is
Restored:
Off - manual
restart
Closed until
reset
Open per temp.
control
Open per
pressure control
Off - manual
restart
Off - manual
restart
Problem  Reduction

What actions should be taken to help neutralize the
impact of the hazards identified above?

Using the results of the hazard evaluation, make sure that
all process operations and equipment will reach a fail-safe
mode upon loss of power. Make sure that devices you
expect to  operate  upon loss of power  are  inspected,
maintained,  and  tested  as  part of  your  equipment
preventative maintenance program. And make sure that
operating procedures and training address these hazards.
Prepare plans and checklists and consider backup power
systems to maintain critical services as described below.

Other actions that should be taken to prevent, prepare for,
and respond to chemical emergencies triggered by power
failure and resumption  can  be addressed by  four
categories:   (1)  preparing  for an  emergency  forced
shutdown   such as  with a rolling  blackout  or  an
approaching electrical storm; (2) preparing for immediate
actions from an unexpected power  loss; (3) restarting
when power is  restored;  and (4) equipment to enhance
continuity of critical services.

1. Emergency Forced Shutdown. Sometimes there may
be a warning or brief notification, perhaps only a few
minutes, that a rolling blackout or other outage (steam,
instrument  air,  cooling water) is about to occur. Many
companies   have  developed  an Emergency  Forced
Shutdown Plan (EFSDP). This Plan addresses only those
priority actions that need to be taken immediately if a
power outage is imminent. The objective is to make the
best use of the short time available to bring the plant to a
safe shutdown condition  and avoid unnecessary upsets
that may be driven by a loss of power. The Plan should
also address follow-up steps that could be taken if time
permits and further steps to secure the unit or process
after the outage.  Finally, the Plan should also include
"load  shedding" steps  to shut  down  less  important
operations,  and thus  conserve power,  steam, cooling
water, or instrument air for the most critical operations.
This Plan should be well thought out, reviewed with  all
involved employees, and periodically tested.

2.  Power Outage:  Immediate Action  Steps.    As
described above, when power dips or is interrupted
unexpectedly,   equipment  should  reach  a fail-safe
condition as specified and designed by you as a result of
your hazard evaluation. Consider developing a checklist
or other tools  for employees to use  to ensure that safe
conditions are reached.  As described  above, the checklist
might show the fail-safe mode for critical equipment and
steps such as closing valves  in reactor feed lines or fuel
supplies  to fired  heaters,  starting auxiliary  power
generators,  and switching to steam or diesel driven backup
pumps or compressors for critical services. In addition,
steps  need  to  be taken  to ensure that there isn't  an
unintended  action when power is restored and to get ready
for restart.   Table 3 shows some lists of equipment and
other checks that may need to be performed after a power
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CHEMICAL ACCIDENTS FROMELECTRICPOPFER OUTAGES
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outage.

Immediately following a brief interruption, there may be
a strong desire to quickly get the process back on-line.
Rushing to put a unit, process, or certain equipment back
on-line may compound  problems associated  with  the
outage as described below.

3. Restarting When Power is Restored. When power
is restored, there are a number of steps that should be
taken to ensure the process (1) remains in a safe mode  and
(2) it is ready to return to operation.  Also, if the process
remained on-line  using  backup  systems, it  must be
returned to normal  operation.   As mentioned  above,
facilities may want to develop plans,  procedures,  and
checklists for restarts or restoring backup services.

Since  power  outages  are  often very short,  consider
developing preplanned warm restart procedures for certain
units, processes or equipment. A warm restart procedure
addresses the unique circumstances that might  arise  if a
unit is not completely shutdown before power is restored
and the unit restarted.

Be sure  that  other necessary support utilities (steam,
instrument  air,  cooling  water, flare gas system,  fire
fighting systems, etc.) have been returned to service  and
are fully operational before restarting operations.
  Table 3.  Sample Check Lists of steps that may
  need to be performed following a Power Outage:

  i/' List manually operated switches that may need
  to be moved to the "off position;
  i^List valves that need to be checked for proper
  position;
  i^List utilities such as steam, instrument air,
  nitrogen blanketing, cooling water, flare system,
  fuel system, radio telephone, pager
  communications, etc. that need to be verified for
  operability;
  i/'Check backup power generators, fire fighting
  systems, and other emergency response equipment
  for operability;
  i/Verify feedstock inventory and availability of
  product storage free space;
  %/List instrument controls, alarms, detection
  devices, automatic shutdown or trip out devices that
  must be reset or have operability verified;
  i^List automatic startup power consuming
  equipment that should be shut down for safety and
  to minimize load demand when power is restored;
  and
  i^List upstream and downstream and other affected
  parties to be notified of shutdown.
Caution: After a very brief outage, there may be a
temptation to quickly restart certain process operations
to  avoid the  hassle  of warm  restart  or complete
shutdown and  restart procedures.   Explosions and
accidental releases have occurred when, for example,
fired heaters and furnaces were restarted without proper
purges or following all prescribed safety steps.  Some
equipment must be brought completely down and purged,
then put back into service following prescribed steps.
The warm restart procedure must address the process
equipment that must first be stabilized and checked out
before restarting, even for a brief outage.

4. Continuity of Critical Services.  As described above
in the Hazard Identification section, if there is critical
equipment that needs to operate to ensure the safe state of
the process or work area, facilities should install backup
power supplies and services. Services such as emergency
pumps, lighting, alarms, and instruments and controls,
particularly computer operated distributed control systems
(DCS)  may  need to  operate  using  backup  power
generators or uninterrupted power supplies (UPS). Steam
or diesel driven pumps should be considered to maintain
critical  flows while  a process  is  shutting  down  or
otherwise dealing with the power outage. And as with all
critical  equipment and procedures, they  should be
maintained, tested, and verified for operation regularly.

Caution: Backup power generators must be selected and
installed by a qualified electric service contractors or
facility personnel. It is particularly important to avoid
improper switching which can lead to power being fed
back into the regular power system.  This feedback can
cause  equipment damage  and injury.   The utility
company should be notified of the installation of any
backup generators.

Recent experiences at large, well established organizations
as well as small and medium size operations have verified
that a greater awareness of the hazards of power failure
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CHEMICAL ACCIDENTS FROMELECTRICPOPFER OUTAGES
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and restart is necessary, especially with thunderstorms
and greater electricity demands in hot weather or ice
storms in freezing weather.  Facilities should re-examine
and ensure that all hazards are identified and addressed
and that equipment, procedures and staff are developed,
maintained, and ready  so that chemical accidents are
prevented and those that do occur are mitigated.

Education     and     Training

Resources

Here are some useful resources for additional information
on power failure and backup power:

Recommended Practice for Emergency and Standby
Power  Systems  for   Industry  and   Commercial
Applications.
The Institute of Electrical and Electronics Engineers,
Inc., (IEEE).
IEEE Operations Center
445 Hoes Lane, P.O. Box 1331
Piscataway, New Jersey 08855-1331 USA
732981 0060
Fax: 732 981  1721
http://www.ieee.org

Caterpillar Alban Engine Power Systems

Describes capacity ranges of portable power generating
equipment and some typical applications.

http://www.dcat.com

National Fire Protection Association (NFPA)
codes include:

NFPA 70 - National Electric Code (latest edition)
NFPA 1600 - Disaster Management (latest edition)
National Fire Protection Association
1 Batterymarch Park
P.O. Box 9101
Quincy, MA 02269-9101
617-770-3000
Customer Service: 800-344-3555
http://www.nfpa.org

Occupational Safety and Health Administration
(OSHA)
Process Safety Management (PSM)
202-219-6151
http://www.osha.gov

Mine Safety and Health Administration (MSHA)
Kaiser Aluminum accident investigation report,
including photographs, Gramercy Works Alumina
Plant Explosion, July 5,  1999.
http://www.mhsa.gov
   For More Information.
      Contact EPA's Emergency Planning and
        Community Right-to-Know Hotline

         (800) 424-9346 or (703) 412-9810
               TDD (800) 553-7672

   Monday-Friday, 9 AM to 6 PM, Eastern Time

                      444

          Visit The CEPPO Home Page:
            http://www.epa.gov/ceppo/
                                             NOTICE

      The statements in this document are intended solely as guidance. This document does not substitute for
      EPA's or other agency regulations, nor is it a regulation itself. Site-specific application of the guidance
      may vary depending on process activities, and may not apply to a given situation. EPA may revoke,
      modify, or suspend this guidance in the future, as appropriate.

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