Hydrocarbon Processing - April 2022 - GP-30

LNG
causing weakening of the container
walls and catastrophic failure.
Fortunately, this is considered a low
probability event for LNG due to
LNG tank design with insulation
layers and storage at atmospheric
pressures with well-designed
pressure relief systems.
FIG. 4. Application of vapor dispersion water sprays and Purple-K dry chemical.
spill of LNG on water generates significantly
more, with as much as ~5,000 ft3
/
min of vapor generation.
For emergency response purposes,
spills are classified as land/water and confined/unconfined.
LNG facility design
includes countermeasures for confining
LNG spills for containment and, therefore,
for vaporization rate stabilization.
Unconfined spills are always producing
vapor at the maximum rate at the leading
edge of the spill where fully warm surfaces
are encountered. These spills spread
in a particular way as they flow downhill
as a liquid, but create a vapor plume that
travels downwind, creating a potentially
broad and rapidly expanding vapor cloud.
LNG vapors produce a plume that can
travel a significant distance before diluting
to a point within the flammable range,
and extreme amounts of radiant heat can
be produced if ignition occurs. LNG vapors
burn at ~2,426°F (~1,330°C), which
is approximately 1.3 times the temperature
of burning gasoline. In addition to
the fire hazard, cryogenic LNG and vapors
will cause severe frostbite if they
contact human skin.
Any LNG facility emergency response
plan will include " LNG spill with/without
fire " cases. This is the primary aspect
that makes LNG facilities different from
other industrial process locations. For the
LNG spill without fire case, cryogenic
fluid contact with both personnel and
equipment/structures poses great concerns.
Unique " rules " for fighting an LNG
fire include:
* Targeting an LNG fire with
water will only increase the
rate of vaporization and make
the fire bigger.
* A condition called rapid phase
transition (RPT) can occur with
30 MARCH/APRIL 2022 | GasProcessingNews.com
LNG, resulting in large " nonburning
explosions " of vapor that
break the sound barrier and make
a loud " pop " noise, so it is
important not to " puncture " the
surface of boiling LNG or " break "
the cushion barrier as it rapidly
boils and moves across a surface.
* LNG fires are fought similarly to
liquefied petroleum gas (LPG)
fires, by isolating hydrocarbon
sources (closing valves) and
bleeding down or blowing down
the pressure behind the leak or spill.
It is preferrable to let the fire burn
itself out rather than extinguish it
and have it potentially re-ignite.
* Dry chemical, such as Purple-K,
and high-expansion foam are
important tools for fighting
LNG fires (FIG. 4). Foam will not
extinguish the fire, but it covers the
surface, lowers the vaporization rate
and allows a more controlled burn
with less radiant heat. Dry chemical
does not stick to the surface of
LNG and smother the fire like in
typical liquid hydrocarbon spills-
it inhibits the chemical chain
reaction, preventing the continuous
burning of the gases even though a
flammable range is present.
* Due to the immense heat released
from an LNG fire, it is important to
consider positioning cooling water
sprays and water application (fire
streams) on adjacent equipment
and structures, if possible.
* A condition called boiling liquid
expanding vapor explosion
(BLEVE) can occur when a fire
impinges on a container, such as a
pressure vessel or even a blockedin
pipeline holding the fluid,
* Rescue emergencies at LNG
facilities are similar to any facility;
however, because many LNG
facilities include a marine terminal,
water rescue is added to trench and
high-angle rescue scenarios.
Takeaways. Successfully resolving an
emergency in an LNG facility begins
with a thorough understanding of the
applicable LNG regulations, continues
with thorough and exceptional planning
for potential emergencies, requires deliberate
measures to stay prepared and
ready for a real emergency, and ends with
successful execution based on preparation
and training.
While each facility operator must
choose how it will ensure these successful
outcomes, an excellent option is to contract
a specialist, third-party organization
with a sole focus on emergency response.
These organizations not only maintain
personnel preparedness through initial
and recurrent training, but also continually
inspect emergency equipment and
systems in the LNG facility to be sure
they are equally as ready to perform as the
personnel. This is an investment that will
pay dividends when needed most. GP
LITERATURE CITED
1
U.S. Department of Transportation, " Pipeline
and hazardous materials
(PHMSA), " 49 CFR Part 193, 2022.
2 Code of Federal Regulations, 33 CFR, Part 127,
" Waterfront facilities handling liquefied natural gas
and liquefied hazardous gas, " February 2022.
Assistant Fire Chief RILEY MAXSON
has 17 yr as an Industrial Firefighter
with 12 yr of experience instructing
industrial emergency classes. He
heads the RTFC Training Academy,
which provides emergency
response training, including LNG,
to clients both domestically and globally.
MAURY HUDSON has 30 yr of
hydrocarbons processing
experience with more than 15 yr
in LNG, where he helped place
RTFC for emergency response
in two USGC LNG export facilities.
He consults for various industry
clients, including LNG facilities.
safety administration
http://www.GasProcessingNews.com
Hydrocarbon Processing - April 2022

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