101116 Audun BrandsæterLNG Safety

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Audun Brandsæter

16 November 2010

Safety Requirements for LNG ships

© Det Norske Veritas AS. All rights reserved.


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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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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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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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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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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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… and to come …



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DNV has contributed actively…

Rules for

Gas FuelledEngine

Installations





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Rules for Classification



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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 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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Some examples…





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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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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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RA results - example



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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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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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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 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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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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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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Safeguarding life, property

and the environment

www.dnv.com

101116 Audun BrandsæterLNG Safety

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