United States
Environmental Protection
Agency
Office of Solid Waste
and Emergency Response
(5104)
EPA 55Q-F-9?-QQ2c
May 199?
f/EPA
LIGHTNING HAZARD TO
FACILITIES HANDLING
FLAMMABLE SUBSTANCES
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. Under CERCLA,
section 104(e) and Clean Air Act CCAA), EPA has authority to conduct chemical accident
investigations. Additionally, in January 1995, the Administration asked the Occupational Safety
and Health Administration fOSHA) and EPA to jointly undertake investigations to determine
the root causefs) of chemical accidents and to issue public reports containing recommendations
to prevent similar accidents. EPA has created a chemical accident investigation team to work
jointly with OSHA in these efforts. Prior to the release of a full report, EPA intends to publish
Alerts as promptly as possible to increase awareness of possible hazards. Alerts may also be
issued when EPA becomes aware of a significant hazard. It is important that facilities, SERCs,
LEPCs, emergency responders and others review this information and take appropriate steps
to minimize risk.
PROBLEM
Lightning strikes that hit equipment
and storage or process vessels
containing flammable materials
can cause devastating accidents at
refineries, bulk plants, processing sites,
and other facilities. This alert is designed
to raise awareness so industry can take
proper precautions.
In recent years, several accidents have
occurred where lightning has struck
facilities handling flammable
substances, resulting in explosions and
fires. In general, there was little or no
information on the lightning protection
used at these facilities, however, given
what is currently known about lightning,
these incidents may have been
preventable.
on 15-20 surrounding tanks to prevent
another explosion; even so, the fire
fatigued four nearby tanks. Although
the explosion and fire caused no deaths
or injuries, about 200 nearby residents
had to be evacuated.
In a 1992 incident, lightning struck a
fiberglass storage tank, setting off a series
of explosions that released toxic fumes
and spread thick smoke over town.
More than 1,000 people were evacuated,
and there were minor injuries, including
nausea, skin irritation, and shortness of
breath.
In a 1977 incident, lightning struck a roof
tank containing diesel fuel. Roof
fragments struck and ignited two other
gasoline tanks; the tanks and gasoline
were destroyed. Property and cleanup
costs were eight million dollars.
In a 1996 incident, lightning struck a
storage tank containing three to four
million gallons of gasoline, causing a
portion of the tank lid to shoot up and
come down on its side into the tank. The
gasoline stored inside did not spill out,
but there was a massive fire that burned
for 28 hours before being put out by
firefighters. Firefighters sprayed water
Lightning strikes cause more deaths,
injuries, and damage than all other
environmental elements combined,
including hurricanes, tornadoes, and
floods. The National Fire Protection
Association (NFPA) estimates there were
26,400 lightning-caused fires annually
between 1989 and 1992; property
damage during this time was estimated
Chemical Emergency Preparedness and Prevention Office
i Printed on recycled paper
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Lightning Hazard to Facilities Handling Flammable Substances
May 1997
to be in the billions of dollars. According to the
Insurance Information Institute, five percent of
all paid insurance claims were lightning-related.
While all types of facilities should evaluate their
lightning safety, storage tanks containing
flammable substances may represent a special
fire or explosion hazard in the event of a
lightning strike; a spark, that might otherwise
cause little or no damage, could ignite
flammable vapors, resulting in a fire or
explosion. Releases of toxic substances also have
occurred.
Lightning is a form of static electricity; it has
extremely high electrical potentials and energy
and can generate extremely high temperatures.
Lightning is a random, capricious event and not
well understood. What is known is that
lightning tends to strike the tallest object on the
ground in the path of its discharge. Parts of
structures most likely to be struck are those that
project above surrounding parts, vents, edge of
roof, wind sock, etc. The bolt generally follows
a conductive path to ground. Lightning may
enter a structure by striking it directly, by striking
a metallic object extending up and out from the
structure, by striking a nearby tree or other tall
object and moving horizontally to the structure,
or by striking overhead wires and being
conducted into the structure by power lines.
Lightning strikes vary in frequency depending
on location. In general, according to the National
Severe Storm Laboratory (NSSL), the U.S.
mainland has a decreasing amount of lightning
toward the northwest. Over the entire year, the
highest frequency of cloud-to-ground lightning
is in Florida between Tampa and Orlando. There
are also high frequencies along the Gulf of
Mexico coast westward to Texas, the western
mountains, the Atlantic coast in the southeast,
and inland from the Gulf. Regions along the
Pacific west coast have the least cloud-to-ground
lightning.
Proper lightning protection provides a
controlled path for the current to follow
back to earth and minimizes the
development of hazardous potential differences.
It may not be possible to completely eliminate
the possibility of damaging accidents caused by
lightning, a random phenomenon. However,
steps can be taken to minimize them. Facilities
should determine an adequate level and type of
protection and then regularly maintain and
inspect the protection systems.
A low impedance path (e.g., lightning rod to
ground) should be offered to prevent the
lightning current from taking other possible
destructive routes. Most metals are good
electrical conductors for low impedance paths
and unaffected by electricity flow. This path
must be a continuous path from the ground
terminal to the air terminal (lightning rod). This
requires that metal parts be interconnected or
bonded so that they maintain the same electrical
potential. This prevents side-flashes or sparks
over disconnected metal parts. Potential gaps
between metallic conductors should be avoided
especially where flammable vapors may escape
or accumulate.
For tanks holding flammable substances,
protection devices, such as air terminals
(lightning rods), bonding and appropriate
grounding systems, conductors (connects air
terminals to grounding system), masts, overhead
ground wires, and other types of protection,
should be considered. The National Lightning
Safety Institute (NLSI) recommends that
connector bonding should be thermal, not
mechanical, where possible. The NLSI also
recommends frequent inspection and resistance
measuring of mechanical connectors. The
configuration of the grounding system is
important and depends upon soil conditions,
building construction, and the presence of other
underground conductors. Grounding systems
can be created with driven ground rods, plates,
and perhaps a counterpoise (a buried cable
encircling the site). Materials adequate to
withstand lightning strikes should be used;
specifically, use of low impedance materials (e.g.
metals) is essential. The grounding system
should be designed for a target resistance of five
ohms/meter resistance or less.
Testing, inspection, and electrical continuity
measurement should be a part of maintenance.
Grounding cables connected to tanks should not
be painted over, corroded, or contain items such
as dirt or bugs that will create a path for
lightning other than to ground. When checking
tanks, put the ohmmeter - the electrical
resistance meter - from cable to tank and note
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Lightning Hazard to Facilities Handling Flammable Substances
May 1997
the reading. The reading should be very low; a
high reading requires cleaning of the
connections.
Some tanks used for storage of flammable
substances may be self-protecting from damage
from lightning and may need no additional
protection; such tanks would include metallic
structures that are electrically continuous, tightly
sealed to prevent the escape of liquids, vapors,
or gases, and of adequate thickness to withstand
direct lightning strikes.
Besides starting fires, lightning can also disrupt
control systems and electrical circuitry more
than two miles away. This can result in
corrupted data, false signals, or immediate or
delayed destruction of sensitive electronics that
could cause an upset or release in your process.
Ordinary fuses and circuit breakers are not
capable of dealing with lightning strikes. Surge
protection for sensitive electronics (such as
process-control circuitry and related PC boards,
computers, and other equipment) should be
used. There are many types and manufacturers
of surge-suppression equipment. The most cost-
effective device should be carefully selected to
handle the currents and voltages expected from
a severe strike. Surge suppressors should be
installed where they can be inspected easily and
replaced when damaged by a severe strike.
Several codes and standards for lightning
protection may be consulted for specific
guidance; examples of such standards are cited
in the next section. Additional information also
may be available from various organizations and
publications.
ON
PROTECTION
Some references that may contain
information about the hazards of lightning
resulting in explosions and methods of
minimizing these hazards are listed below.
Regulations potentially applicable to facilities,
and codes and standards that may be relevant
are also listed below.
For more information consult the following:
Section 112(r) of the Clean Air Act focuses on
prevention of chemical accidents. It imposes on
facilities with regulated substances or other extremely
hazardous substances a general duty to prevent and
mitigate accidental releases. Accident prevention
activities include identifying hazards and operating
a safe facility.
EPA's Risk Management Program (RMP) Rule [40
CFR 68] is intended to prevent and mitigate
accidental releases of listed toxic and flammable
substances. Requirements under the RMP rule
include development of a hazard assessment, a
prevention program, and an emergency response
program.
The Occupational Safety and Health Administration
(OSHA) has the Process Safety Management
Standard, which includes regulations on fire
prevention.
Occupational Safety and Health
Administration
Phone: (202) 219-8151 - Public Information
Web site: http://www.osha.gov
Codes
The American Petroleum Institute (API) has
standards relevant to lightning protection at facilities.
American Petroleum Institute
1220 L St NW
Washington DC 20005
Phone: (202) 682-8000
Web site: http://www.api.org
Relevant API standards include:
API RP 2003 — Protection Against Ignitions
Arising Out of Static, Lightning, and Stray-
Currents, fifth edition, 1991.
API PUBL 2210 — Flame Arrestors for Vents of
Tanks Storing Petroleum Products, second
edition, 1982.
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Lightning Hazard to Facilities Handling Flammable Substances
May 1997
The National Fire Protection Association (NFPA) has
lightning and flammable/'combustible liquid cades.
National Fire Protection Association
1 Batterymarch Park
P.O. Box 9101
Quincy, MA 02269-9101
Phone: (617) 770-3000
Customer Service: 1 (800) 344-3555
Web site: http://www.nfpa.org
Relevant NFPA codes include:
NFPA 30 — Flammable and Combustible
Liquids Code. 1996.
NFPA 70 — National Electric Code, 1996.
NFPA 77 — Static Electricity. 1993.
NFPA 780 — Lightning Protection Code, 1995.
NFPA 921 — Guide for Fire and Explosion
Investigations, 1995.
NFPA 1600 — Disaster Management. 1995.
Underwriters Laboratories Inc. (UL) has standards
for product safety.
Underwriters Laboratories Inc.
333 Pfingsten Rd
Northbrook, IL 60062
Phone: (847) 272-8800
Web site: http://www.ul.com
Relevant UL standards include:
UL 96 - Lightning Protection Components, 1994.
UL 96A - Installation Requirements for
Lightning Protection Systems, 1994.
UL 198G - Fuses for Supplementary Overcurrent
Protection. 1988.
UL 467 - Grounding and Bonding Equipment,
1993.
UL 525 - Flame Arresters. 1993.
UL 1077 - Supplementary Protectors for Use in
Electrical Equipment, 1994.
to
The Lightning Protection Institute (LPI) has
endorsed official programs since the 1970s for the
certification of properly installed lightning protection
systems.
Lightning Protection Institute
3335 N. Arlington Heights Rd, Suite E
Arlington Heights, IL 60004
Phone: 1 (800) 488-6864 or (847) 577-7200
Web site: http://lightning.org
Relevant LPI standards include:
LPI-175 - Lightning Protection Systems Standard
of Practice
The National Lightning Safety Institute's (NLSI)
mission is to improve lightning safety through various
activities including establishing specific audit and
certification protocols, as well as engineering site
survey programs.
National Lightning Safety Institute
891 N. Hoover Ave.
P.O. Box 778
Louisville, CO 80027
Phone: (303) 666-8817
Web site: http://www.lightningsafety.com
A list of firms providing lightning protection
technologies can be obtained locally through the
Internet by using the search terms ''lightning and
protection", and through LPI, NLSI, or the
United Lightning Protection Association
(ULPA).
United Lightning Protection Association
P.O. Box 22683
Lake Buena Vista, FL 32830
Phone: 1 (800) 668-ULPA (8572)
The ULPA does not currently have a web page.
UL1449 - Transient Voltage Surge Suppressors,
1996.
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Lightning Hazard to Facilities Handling Flammable Substances
May 1997
FOR MORE INFORMATION...
CONTACT THE 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
VISIT THE CEPPO HOME PAGE ON THE WORLD
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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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