101116 audun brandsæterlng safety
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Audun Brandsæter
16 November 2010
Safety Requirements for LNG ships
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Safety Requirements for LNG ships
16 November 2010
2
Topics
Ship design and features
How safe is LNG as an on-board fuel?
How safe is it to transfer between two ships?
Special Studies for risk identification and mitigation
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Safety Requirements for LNG ships
16 November 2010
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LNG Carriers
LNG has been traded and used in a large scale
for more than 50 years
with more than 350 LNG carriers; old ones, BIG ones and small ones.
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Safety Requirements for LNG ships
16 November 2010
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What is LNG?
Condensed natural gas
Volume reduced by factor 600 for transportation
LNG is a cryogenic hydrocarbon liquid.
- Contains mainly methane with traces of LPG, and Nitrogen
- SO2, CO2, H2O, C6+ and other contaminants removed to allow for cooldown without frost formation, lean
fuel.
- Normally stored at atmospheric pressure where it boils at -160 deg C
- Heat from surrounding will cause boil off. If boil off is contained the pressure and temperature will rise.
Alternatively the boil off can be reliquefied.
Density of LNG is appr. 420 kg/m3
Energy content of 1 m3 LNG corresponds to 0.65 m3 diesel
Natural gas is flammable (as all hydrocarbons)
Natural gas is non toxic
Cold natural gas is heavier than air. At approximately -100 °C it will be buoyant and rise.
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Safety Requirements for LNG ships
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LNG compared to other Hydrocarbon liquids.
- The combustion characteristics are less
severe than other hydrocarbons
- Ignition requires higher temperatures
compared to other HC
- The cold and dense gas close to the
release and directly above the boiling liquid
pool is too rich for ignition
- Diluted and flammable gas is buoyant
- Burning characteristics are less aggressive
than eg propane; detonations are highly
unlikely
- The cryogenic properties are particular
for LNG and requires attention
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Safety Requirements for LNG ships
16 November 2010
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The world’s ships on LNG fuel built to DNV class!*
… other LNG fuelled ships today …
DNV has proven rules for LNG fuelled engines since 2001
* LNG tankers excluded
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Safety Requirements for LNG ships
16 November 2010
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… and to come …
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Safety Requirements for LNG ships
16 November 2010
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DNV has contributed actively…
Rules for
Gas FuelledEngine
Installations
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Safety Requirements for LNG ships
16 November 2010
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Rules for Classification
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Safety Requirements for LNG ships
16 November 2010
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IMO - IGC CodeInternational Code for the Construction and Equipment of Ships
Carrying Liquefied Gases in Bulk
IMO - IGF CodeInternational Code of Safety for Gas-fuelled Ships
(at present: Interim Guidelines on Safety for
Natural Gas-fuelled Engine Installations in Ships)
SIGGTOGuidelines for LNG transfer
OCIMFGuidelines for Oil transfer, ship to ship oil bunker procedures
Onshore regulationsEU , NFPA, FERC…..
Port regulationsUSCG, local authorities
International and national regulations and guidelines
Flag State, e.g. NMD Regulations concerning.. cargo ships with natural gas fuelled internal combustion engines.
.. the construction and operation of gas-fuelled passenger ships
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Safety Requirements for LNG ships
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Safety principles
Two alternative system configurations may be accepted:
Inherently gas safe machinery spaces: Arrangements in machinery spaces are such
that the spaces are considered gas safe under all conditions, normal as well as
abnormal conditions i.e. inherently gas safe.
ESD protected machinery spaces: Arrangements in machinery spaces are such that
the spaces are considered nonhazardous under normal conditions, but under
certain abnormal conditions may have the potential to become gas hazardous. In
the event of abnormal conditions involving gas hazards, emergency shutdown
(ESD) of non-safe equipment (ignition sources) and machinery shall be
automatically executed while equipment or machinery in use or active during these
conditions shall be of explosion protected design.
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Safety Requirements for LNG ships
16 November 2010
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Some examples…
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Safety Requirements for LNG ships
16 November 2010
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Documentation / Assessment requirements by NMD
Regulation 644 concerning cargo ships with natural gas fuelled internal combustionengines, § 8 Documentation:
- A formal safety assessment shall be undertaken for any new or altered concept,which is required to document a safety level which is at least equivalent to a new,
comparable diesel-engine vessel.
Regulation 1218 concerning the construction and operation of gas-fuelledpassenger ships, § 7 Risk Analysis:
- The safety level of a gas-fuelled passenger ship shall at least be equivalent to thesafety level of a new diesel-powered ship.
Formal Safety Assessment / Risk Analysis
Explosion Assessment / Explosion Analysis
New:
Circular letter RSV-14-2010 opens for the use of IMO Interim Guidelines asalternative to above Regulations.
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Safety Requirements for LNG ships
16 November 2010
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Assement structure
Concept
Risk Analysis
Design
Risk Analysisincl. Explosion analysis
Updated Design
Risk Analysisincl. Explosion analysis
Updated 3rd Party
Consequence and
Risk Assessment
Third Party
Consequence and
Risk Assessment
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Safety Requirements for LNG ships
16 November 2010
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RA results - example
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Safety Requirements for LNG ships
16 November 2010
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Fatality risk per 1 billion passenger·km
5,60
0,86
3,88
1,15 1,45
0,18
0
1
2
3
4
5
6
Personbil Flyinnenriks
rute
Fly(inkludert
allekategorier
flyging)
Tog Tog (Åsta-ulykken
inkludert)
Trikk/T-bane
D r e p t e
p e r m
r d
p k m
Ferries in
Norway
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Safety Requirements for LNG ships
16 November 2010
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Ongoing QRAs for gas fuelled vessels
Offshore supply vessels:
Island Offshore / Rolls Royce, STX Brevik
DOF, STX Søvikneset – H738
Solstad, STX Langsten – H755
Eidesvik / Wärtsilä Norway, Kleven
Coaster:
Nordnorsk skipskonsult, 70 m general cargo vessel
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Safety Requirements for LNG ships
16 November 2010
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Ship-to-Ship transfer of LNG
A technology development project called “LNG bunkering Ship to ship” is ongoing
with the aim of developing a concept for transfer of LNG (liquefied natural gas),
between two ships.
Challenge: rapid bunkering operation, in proximity to urban areas w/ simultaneous
cargo and passenger handling.
Covering both the operational bunkering process and technical solutions.
Bunkering operation shall not affect the retention period in port.
Establishing a safe and time efficient bunkering procedure of LNG transfer from ship
to ship.
To pave the way for establishing an international standard and accompanying
guideline for safe and time efficient bunkering of LNG
A recognised standardized way of performing LNG-bunkering is believed to be an
important contributor to a safe operation.
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Safety Requirements for LNG ships
16 November 2010
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Safety issues for LNG
Releases can lead to
- frost burns and personnel injuries
- brittle fractures and structural failure for exposed
steel
- flammable clouds
- fires and explosions
- RPT (Rapid Phase Transition or “cold
explosions”)
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Safety Requirements for LNG ships
16 November 2010
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Safeguards against LNG releases
Safeguards against releases comprise
- Operational Procedures
- Strict requirements to the integrity of the containment to avoid release
- Personnel protective equipment
- Protection of exposed structures
- Fire and gas safeguards comparable with other hydrocarbons.
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Safety Requirements for LNG ships
16 November 2010
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Technically no obstacles and it is safe
LNG technology safe and well proven
- Half a century of LNG tanker operation
- Used as marine fuel since 2000, now in some 20 ships
- Ongoing research to further improve technical and economical aspects- Even higher efficiency - thus reduced emissions - possible
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Safety Requirements for LNG ships
16 November 2010
22
Safeguarding life, property
and the environment
www.dnv.com