Safety Aspects of CNG and LNG Systems
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Transcript of Safety Aspects of CNG and LNG Systems
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Assignment Title:
Safety Aspects in Compressed Natural Gas and
Liquefied Natural Gas (LNG)
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Assignment ReportOn
Safety Aspects in Compressed Natural Gas and
Liquefied Natural Gas (LNG)
Submitted toProf. V.P. Sharma
Dept. of Petroleum EngineeringBy
Sr.no Name Admission Number
11. Kevin Lodha 15MT000273
12. Chandan Sahu 15MT000277
13. Vineet Tyagi 15MT000278
14. Krishan Patidar 15MT000282
15. Pranav Dubey 15MT000290
16. Yash Saragiya 15MT000294
17. Madhukar. S 15MT000296
18. M Afzal Akthar 15MT000306
19. Varun Patel 15MT000367
1stYear Masters of Technology
Department of Petroleum Engineering,
Indian School of Mines, Dhanbad, Jharkhand. India
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SERIAL NO. TOPIC PAGE
1. INTRODUICTION TO CNG 4
1.1 CNG SUPPLY CHAIN 4
2. DESIGN AND SAFETY OF CNG STATIONS 5
2.1 SAFETY FEATURES IN CNG COMPRESSORS 5
2.2 SAFETY FEATURES IN ELECTRICALCONNECTIONS
7
2.3 SAFETY FEATURES IN CASCADES 8
2.4 SALIENT FEATURES OF DISPENSERS 8
2.5 SAFETY FEATURES IN CONDUCTIVE HOSES ANDEARTHING
9
2.6STATION TUBING AND FITTINGS 9
2.7 FIRE PROTECTION SYSTEM IN CNG STATIONS 9
3 SAFETY PRACTICES IN OPERATION AND
MANAGEMENT OF A CNG PLANT
10
4 INTRODUCTION TO LNG 10
5 BRIEF OVERIVEW OF THE LNG VALUE CHAIN 11
6 SAFETY CONSIDERATIONS IN LNG OPERATIONS 12
6.1 PRIMARY CONTAINMENT 13
6.2 SECONDARY CONTAINMENT 15
6.3 SAFEGUARD SYSTEMS 16
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SERIAL NO. DESCRIPTION PAGE
1. CNG SUPPLY CHAIN. 4
2. CNG SUPPLY CHAIN HIGHLIGHTING
COMPRESSION STAGE.
5
3. GAS DETECTORS INSIDE COMPRESSOR. 6
4. FLAME DETECTORS INSIDE COMPRESSOR 7
5. CNG SUPPLY CHAIN HIGHLIGHTING CASCADE
STAGE.
8
6. CNG SUPPLY CHAIN HIGHLIGHTING
DISPENSER STAGE.
8
7. CONTINUOUS IMPROVEMENT OF LNG SAFETY
, ENVIRONMENTAL AND SAFETY
INFRASTRUCTURE
11
8. LNG VALUE CHAIN 11
9. CRITICAL SAFETY CONDITIONS IN LNG
STORAGE.
12
10. CONCEPTUAL DESIGN OF STORAGE TANKS. 14
11. SINGLE CONTAINMENT TANK 14
12. MEMBRANE TYPE STORAGE LNG SHIP. 15
13. DOUBLE CONTAINMENT TANKS 15
14. FULL CONTAINMENT TANKS 16
15. TANK SECTION OF A SPHERICAL MOSS
DESIGN
16
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1. INTRODUCTION TO CNG
CNG is made of Natural gas which is compressed to 250 Kg/cmg through reciprocating compressors
installed at Mother and On-Line CNG Stations for use as automotive fuel. CNG is dispensed to vehicles atmaximum 200 Kg/cmg pressure. CNG is artificially odorized using Ethyl Mercaptan.
Physical Properties of CNG:
Colourless
Non-toxic
Lighter than air
Non-corrosive
1.1. CNG Supply Chain:
The below diagram shows the typical stages in a CNG supply chain from supply end to consumer end.
Fig 1:CNG Supply Chain. Source:Indraprasta Gas Ltd.
PROPERTIESCNGs VALUES
CALORIFIC VALUE 10600 KCAL/KG
RELATIVE DENSITY 0.65 (AIR=1)
AUTOIGNITION TEMPERATURE 540 C
FLAMMABILITY LIMIT 5-15 % IN AIR
FLAME TEMPERATURE 1790 C
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2. DESIGN AND SAFETY FEATURES OF CNG STATIONS
The CNG Stations are designed as per Best National & International Codes and Standards.
Safety features of major sections in the supply chain are described below:
2.1. Safety Features in CNG compressors
Fig 2:CNG Supply Chain highlighting Compression Stage. Source:Indraprasta Gas Ltd.
2.1.1. Salient Features of Compressors
TYPE RECIPROCATING
CAPACITY 2501200 SCM/HR.
DISCHARGE PRESSURE 255 KGS./CM2G
DESIGN CODE API-11P, OISD 179, NFPA-37, ANSI, ASTM, NEC, NEMA,
INDIAN ELECTRICITY RULES AND INDIAN EXPLOSIVE ACT.
PRIME MOVER GAS ENGINE / ELECTRIC MOTOR
SAFETY FEATURES
PLC CONTROL WITH ALL SAFETY INTERLOCKS, CO2
FLOODING SYSTEM, LEL DETECTORS, UV/INFRARED
FLAME DETECTORS AND ESD SYSYTEM
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2.1.2. Brief Description of Safety features in Compressors
2.1.2.1. PLC Control
The unit is designed for fully automated, unattended operation.
Auto start, auto stop, alarm & trip on development of abnormal condition through PLC control.
The unit goes into a safe mode in case of any fault.
2.1.2.2. Safety Interlocks
Safety interlocks are provided in the PLC system to give Audio-Visual alarm & trip the unit whenever any of
these parameters crosses the High/Low limits:
High Discharge Pressure : Each stage
Low Pressure : Suction, Engine Lube Oil, Compressor Oil High Temperature : Each stage, Lube Oil, Coolant
Gas Leakage in the Package
Flame
Low Level : Lube Oil, Coolant
High Vibration
2.1.2.3. Lower Explosive Limit (LEL) & Flame Detectors
2 Nos. of LEL Detectors or more in each partition of the package are provided to sense gas leakage
2 Nos. of UV / IR flame detectors or more are provided in each partition of the package to senseflame.
The signals of each of these sensors will be continuously monitored by the PLC system. Upon
sensing presence of Gas or Flame, the PLC trips the unit, and isolates it from suction line, CNG
dispensers & the cascades.
In case a flame is sensed, the CO2 Flooding system is activated to immediately extinguish the fire.
Fig 3:Gas Detectors inside Compressor. Source:Indraprasta Gas Ltd.
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Fig 4:Flame Detectors inside Compressor. Source:Indraprasta Gas Ltd.
2.1.2.4. CO2Flooding Station
The compressor package is provided with a CO2flooding system, which is triggered by signal from
the UV/IR flame detectors.
On detection of flame, CO2is discharged to extinguish the fire.
2.1.2.5. Ignition System
The Natural Gas Engine is provided with a Breaker-less Ignition system. There is no distributor in the
system, which might be a potential source of spark.
All the wiring harness of the Ignition system are enclosed in grounded, metal shielded flexible
conduits, thus any leakage current does not generate spark.
The Ignition transformers are mounted on the spark plug, avoiding any high tension cable.
Engine Silencer is Residential / Hospital type with Exhaust Flame trap and Spool type Flexible
Connector.
2.1.2.6. Emergency Shut Down (ESD) System
The CNG compressor packages are provided with an Emergency Shut Down System.
The ESD system is activated by pushing a Mushroom Head type Emergency switch mounted in a
safe & accessible location.
The ESD system, when activated, brings the unit to an immediate halt.
Isolates the unit from Gas Suction Line.
Closes all the output priority valves, thus isolating the Compressor, Cascades & Dispensers from
each other.
2.2. Safety Features In Electrical Connections
All the Cables are terminated with Double compression Explosion -proof glands.
The Electric Motors are Explosion Proof, with Motor Protection relays, with Multiple safety
features.
All the instruments / sensors are intrinsically safe, suitable for hazardous area application.
Any Loose Wiring / Failure of any sensor / instrument takes the PLC to fail safe mode.
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2.3. Safety features in Cascades
Fig 5:CNG Supply Chain highlighting Cascade Stage. Source:Indraprasta Gas Ltd.
Pressure Relief Devices (PRD) are provided in the form of burst discs with fusible plug, to relieve the
excess pressure.
The vent of relief devices of individual cylinders is combined into a common manifold & released to
atmosphere at a safe location.
CNG cylinders are hydro-tested every 5 years.
2.4. Salient Features of Dispensers
Fig 6:CNG Supply Chain highlighting Dispenser Stage. Source:Indraprasta Gas Ltd.
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2.4.1. Safety Features in Dispensers
Over fill protection
ESD Manual
Break Away Coupling with Auto cut off Device when exceeding 200 Kg/cm2
2.4.2. Design Codes:
CODENFPA 52, NGV 4.2/A.G.A. 1-93, ANSI/NGV1,NGV 4/A.G.A.,AG901,IS 5572, IS 5571, OISD 179
AND OISD 113
2.5. Safety Features in Conductive Hoses and Earthing
The filling Hoses of CNG Dispensers are Electrically Conductive & designed as per ANSI / NGV 4.2
Static charge is carried to dispenser body, and does not produce spark during engagement and
disengagement of filling nozzle with Vehicle receptacle.
The dispensers are Earthed to dissipate the Static Charge, and leakage current if any.
2.6. Station Tubing and Fittings
All the High Pressure Tubing at CNG stations is made of Stainless Steel, which does not corrode.
All the tubing Connections are Double Ferrule type.
All tubing & fittings are procured from internationally reputed vendors.
2.7. Fire Protection Systems in CNG stations
A)Fire Fighting Arrangements as per OISD-179:
EQUIPMENT DCP-75 Kg DCP- 10 Kg CO2 4.5 Kg
COMPRESSOR 1 1 -DISPENSER - 1 -
CASCADE - 1 -
LCV POINT - 1 -
ELECTRICAL PANEL - - 1
B)As Per CCOE Guidelines : 6 Nos. Fire Buckets at each CNG Station
C) Additional Safety Measures By IGL: CO2 Flooding systems for compressors are installed as
Standard Safety measures.
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3. SAFETY PRACTICES IN OPERATION AND MANAGEMENT OF A CNG PLANT
Preventive Maintenance of Equipment
Regular Testing and Calibration
CNG is odorized for easy detection in case of leakage Portable & fixed Gas Detectors for Checking Leaks
Compressor Area Fenced
Installation of Safety Guards for Dispensers
Safety & Operational Training to all staff
Safety Manual with all safety & emergency information.
Safety Work Permit System followed.
Display of Safety Film on CNG.
Use of required Personal Protective Equipment
Safety Committee for worker participation.
Safety Audit / Safety Inspection conducted. Accident Reporting, Recording, Investigation & Analysis
Safety Awareness and Campaign conducted.
CNG refuelling is done with no passengers in the vehicle
Ignition keys of vehicles are removed before refuelling
4. INTRODUCTION TO LNG
LNG has been transported and used safely in the U.S. and worldwide for roughly 40 years. U.S. has thelargest number of LNG facilities in the world, scattered throughout the country and located near
population centers where natural gas is needed.
Analysis of data on LNG safety and security indicates an excellent safety record. This strong safety
record is a result of several factors:
First, the industry has technically and operationally evolved to ensure safe and secure
operations. Technical and operational advances include everything from the engineering
that underlies LNG facilities to operational procedures to technical competency of personnel.
Second, the physical and chemical properties of LNG are such that risks and hazards are easily
defined and incorporated into technology and operations. Third, a broad set of standards, codes and regulations applies to the LNG industry to further
ensure safety. These have evolved through industry experience worldwide and affect LNG
facilities and operations everywhere. Regulatory compliance provides transparency and
accountability.
As long as safety and security standards and protocols developed by the industry are maintained and
implemented with regulatory supervision, the transportation of LNG is considered safe. It is in the best
interest of the industry, regulators and the general public that this goal be achieved so that the benefits of
natural gas can be realized for consumers.
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Fig 7:Continuous Improvement of LNG Safety , Environmental and Safety Infrastructure
5. BRIEF OVERVIEW OF THE LNG VALUE CHAIN
The major components of the value chain include the following:-
Natural gas production, the process of finding and producing natural gas for delivery to a processing
facility.
Liquefaction, the conversion of natural gas into a liquid state so that it can be transported in ships.
Transportation, the shipment of LNG in special purpose ships for delivery to markets. Re-gasification, conversion of the LNG back to the gaseous phase by passing the cryogenic liquid
through vaporizers.
Distribution and delivery of natural gas through the national natural gas pipeline system and
distribution to end users.
Fig 8:LNG Value Chain
Storage is a major focus for safety and security. Once natural gas is liquefied, it is stored before shipment
or loaded directly into the ship. LNG ships are required to have double hulls by regulation (International
Maritime Organization) to facilitate safe transportation by sea. LNG receiving terminals and re-
gasification facilities store LNG before it is re-gasified for pipeline transportation.
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6. SAFETY CONSIDERATIONS IN LNG OPERATIONS
The LNG industry is subject to the same routine hazards and safety considerations that occur in any
industrial activity. Risk mitigation systems must be in place to reduce the possibility of occupationalhazards and to ensure protection of surrounding communities and the natural environment. As
with any industry, LNG operators must conform to all relevant national and local regulations, standards
and codes.
Beyond routine industrial hazards and safety considerations, LNG presents specific safety considerations.
In the event of an accidental release of LNG, the safety zone around a facility protects neighbouring
communities from personal injury, property damage or fire. Indeed, during the past four decades, growth
in LNG use in worldwide has led to a number of technologies and practices that will be used in the
U.S. and elsewhere in the world as the LNG industry expands.
Generally, multiple layers of protection create four critical safety conditions, all of which are integrated
with a combination of industry standards and regulatory compliance, as shown.The four requirements for safety primary containment, secondary containment, safeguard
systems and separation distance apply across the LNG value chain, from production, liquefaction
and shipping, to storage and re-gasification. (We use the term containment in this document to
mean safe storage and isolation of LNG.)
Fig 9:Critical Safety Conditions in LNG Storage.
Primary Containment: The first and most important safety requirement for the industry is to
contain LNG. This is accomplished by employing suitable materials for storage tanks and other
equipment, and by appropriate engineering design throughout the value chain.
Secondary Containment: This second layer of protection ensures that if leaks or spills occur, the
LNG can be contained and isolated. For onshore installations dikes and berms surround liquid
storage tanks to capture the product in case of a spill. In most of installations a reinforced concrete
tank surrounds the inner tank that normally holds the LNG. Secondary containment systems are
designed to exceed the volume of the storage tank. As will be explained later, double and full
containment systems for onshore storage tanks can eliminate the need for dikes and berms.
Safeguard Systems:In the third layer of protection, the goal is to minimize the release of LNG andmitigate the effects of a release. For this level of safety protection, LNG operations use systems
such as gas, liquid and fire detection to rapidly identify any breach in containment and remote and
automatic shut off systems to minimize leaks and spills in the case of failures. Operational systems
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(procedures, training and emergency response) also help prevent/mitigate hazards. Regular
maintenance of these systems is vital to ensure their reliability.
Separation Distance: Federal regulations have always required that LNG facilities be sited at a safe
distance from adjacent industrial, communities and other public areas. Also, safety zones are
established around LNG ships while underway in U.S. waters and while moored. The safe distances
or exclusion zones are based on LNG vapor dispersion data, and thermal radiation contours andother considerations as specified in regulations.
Industry Standards/Regulatory Compliance : No systems are complete without appropriate
operating and maintenance procedures being in place and with insurance that these are
adhered to, and that the relevant personnel are appropriately trained. Organizations such as
the Society of International Gas Tanker and Terminal Operators (SIGTTO), Gas Processors
Association (GPA) and National Fire Protection Association (NFPA) produce guidance which
results from industry best practices.
The four conditions described above for safety, along with industry standards and regulatory
compliance, are vital to continuing the strong LNG industry safety performance. They are essential if
LNG is to play an increasing role in the U.S., both for energy security and to protect the flow of
economic benefits from LNG to our society as a whole.
6.1. Primary Containment
6.1.1. General Primary Containment in LNG Tanks
International standards and rules define containment with respect to types of structures and
technologies in use. We use the term containment in this document to mean safe storage andisolation of LNG. Safe use of LNG, or any cryogenic substance, requires an understanding of how
materials behave at cryogenic temperatures. For example, at extremely low temperatures, carbon steel
loses its ductility and becomes brittle. The material selected for tanks, piping, and other equipment that
comes in contact with LNG is critical. The use of high nickel content steels, aluminium, and stainless
steels is costly but necessary to prevent embrittlement and material failures. High alloy steels
composed of nine per-cent nickel and stainless steel typically are used for the inner tank of LNG storage
tanks and for other LNG applications.
Several engineering design features ensure the safety of LNG storage tanks (see Figure) .LNG typically is
stored in double-walled tanks at atmospheric pressure. The storage tank is a tank within a tank, with
insulation between the walls of the tanks.
In single containment tanks, the outer tank is generally made of carbon steel, it provides no protection
in the event of the failure of the inner tank it holds the insulation in place. The inner tank, in contact
with the LNG liquid, is made of materials suitable for cryogenic service. It has a flat metallic bottom and a
cylindrical metal wall both built of materials suitable for cryogenic temperatures (usually nine percent
nickel steel).
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Fig 10:Conceptual design of storage tanks. Source:Shell
Pre-stressed concrete and aluminium have also been used for inner tanks. The inner tank bottom rests on
a rigid insulation material, such as foam glass. The strength of the total tank must withstand the
hydrostatic load of the LNG. This hydrostatic head determines the thickness of the inner tank side walls.
The tanks also have an insulation layer with a flat suspended deck supported by an outside domed roofvapor barrier or outer tank (often made of carbon steel). All new tank piping designs are through the roof
of the tank to avoid siphoning of the full content of the tank in case of piping failures.
Fig 11:Single Containment Tank
6.1.2. Primary containment in LNG ships
Engineering design for safety also applies to LNG ships. An on-board containment system stores the LNG,
where it is kept at atmospheric pressure (to keep air from entering the tank) and at -256oF (-160oC).
Existing LNG ship cargo containment systems reflect one of three designs. As of September 2006:
Spherical (Moss) design accounts for 44 percent of the existing ships,Membrane design account for about 51 percent, and
Self-supporting structural prismatic design account for about 5 percent.
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Ships with spherical tanks are most readily identifiable as LNG ships because the tank covers are visible
above the deck. Many ships currently under construction, however, are membrane type ships. The
membrane and prismatic ships look more like oil tankers with a less visible containment tank structure
above the main deck.
The cargo containment systems of membrane-type LNG ships are made up of a primary container (Fig
below) , a secondary containment and further insulation.
Fig 12:Membrane Type Storage LNG Ship.
The primary container is the primary containment for the cargo. It can be constructed of stainless steel,
invar (36 percent nickel steel). The most common cargo insulation materials include polyurethane,
polyvinyl chloride foam, polystyrene and perlite. Nitrogen is placed in the insulation space. Because
nitrogen does not react with other gases or materials, even minor leaks can be detected by
monitoring the nitrogen-filled insulation space for the presence of methane.
6.2 Secondary Containment:
Secondary containment provides protection beyond the primary containment. This applies both to storage
tanks at receiving/re-gasification terminals as well as LNG ships. A dike, berm or dam impoundmentusually surrounds a single containment tank located onshore in order to contain any leakage in the unlikely
event of tank failure. This system allows any released LNG to be isolated and controlled. The dikes are
designed to contain 100 percent to 110 percent of tank volume and to be high enough so that the
trajectory of a leak at the upper liquid level in the tank will not over-shoot the edge of the dike. Single
containment tanks require larger land areas for LNG storage facilities because of the larger potential spill
area of the dike impoundment.
6.2.1. Double containment Tanks : A double containment tank is designed and constructed so that both
the inner tank and the outer tank are capable of independently containing the refrigerated liquid. The
inner tank contains the LNG under normal operating conditions. The outer tank or wall is intended tocontain any LNG leakage from the inner tank and the boil-off gas. The majority of LNG storage tanks
built recently around the world is designed as double or full containment tanks.
Fig 13:Double Containment Tanks
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6.2.2. Full containment Tanks:Similar to a double containment tank, a full containment tank is designed
and constructed so that both the inner tank and the outer tank are capable of independently containing
the stored LNG. The inner tank contains the LNG under standard operating conditions. The outer tank or
wall composed of approximately three feet of concrete is one to two meters away from the inner tank. The
outer tank supports the outer roof and is intended to contain the LNG. The tanks are designed in
accordance with international LNG codes (EMMUA 147,EN 1473). The full containment tank is lesssusceptible to damage from external forces.
Fig14:Full Containment Tanks
6.2.3. Secondary containment in ships:For LNG ships, regulations concerning a secondary barrier depend
on the type of construction of the storage tanks. It may be complete secondary containment mechanism
for membrane design ships that is equivalent to the primary barrier. In the case of ships with independent
tanks, such as the spherical and structural prismatic design systems, the secondary barrier is a splash
barrier with a drip pan at the bottom from which accumulated liquid evaporates. Materials used to
construct the secondary barrier include aluminium or stainless steel foil, stainless steel and invar.
Fig15:Tank section of a Spherical Moss design
6.3. Safeguard SystemsAll LNG facilities are designed to comply with spill containment requirements. They have extensive safety
systems to detect LNG releases using a number of gas detectors (for methane), ultraviolet or infrared fire
detectors, smoke or combustion product detectors, low temperature detectors and detectors to monitor
LNG levels and vapor pressures. Closed-circuit television systems monitor all critical locations of LNG
facilities. Emergency shutdown systems can be activated upon detection of leaks, spills, or gas vapors.
While there are different types of designs for LNG facilities, health, safety and environmental (HSE)
considerations are generally similar. Various codes and standards (see Industry Standards and
Regulation section) ensure that the chances of a release are minimal, as is its volume if a releaseoccurs.
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LNG transfer linesare designed to prevent releases. Should there be a failure of a segment of piping at an
LNG facility, a spill of LNG or leak of gas vapor could occur. An LNG spill from a transfer line is very unlikely
due to the design requirements for equipment, such as use of proper materials of construction, minimal
use of bolted flanges and rigorous testing of LNG piping. Gas and fire detectors throughout the facility
activate alarms and foam systems to ensure rapid dispersion or containment of gas vapors and any fire
hazard.Fire detection sensors at LNG facilities would sound an alarm and immediately begin a shutdown
procedure. Foam, dry chemical and/or water would be dispersed immediately from automated
firefighting systems. If there is an ignition source, then a pool fire would develop at the liquid LNG release
point. LNG vapor burns with very little smoke. The LNG quickly evaporates due to the heat of the
surroundings and the flame. If a release of LNG goes unignited for a period of time, then a vapor
cloud can form. If ignited, a vapor cloud burns back to the source of the release. The speed of burn
depends on conditions such as the size of the release and weather conditions.
Safeguard system in LNG Ships: LNG ships are designed with a double hull. This design provides optimum
protection for the integrity of the cargo in the event of collision or grounding as well as separate ballast.Separate from the hull design, LNG ships have safety equipment to facilitate ship handling and cargo
system handling. The ship-handling safety features include sophisticated radar and positioning systems
that enable the crew to monitor the ships position, traffic and identified hazards around the ship. A
global maritime distress system automatically transmits signals if there is an on-board emergency
requiring external assistance. The cargo-system safety features include an extensive instrumentation
package that safely shuts down the system if it starts to operate outside of predetermined parameters.
Ships also have gas and fire detection systems, and nitrogen purging. In case fire occurs on a ship, two 100
percent safety relief valves are designed to release the ensuing boil off to the atmosphere without over-
pressurizing the tank.
LNG ships use approach velocity meters when berthing to ensure that the prescribed impact velocityfor the berth fenders are not exceeded. When moored, automatic mooring line monitoring provides
individual line loads to help maintain the security of the mooring arrangement while alongside. When
connected to the onshore system, the instrument systems and the shore-ship LNG transfer system acts as
one system, allowing emergency shutdowns of the entire system from ship and from shore.
LNG ships and facilities have redundant safety systems, for example, Emergency Shutdown systems
(ESD). A redundant safety system shuts down unloading operations when the ship or unloading facility is
not performing within the design parameters.
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7. References
1] Sharma, Alok. Safety in CNG/PNG Operations. Indraprasta Gas Limited.2] Rajeev, B. Safety in Natural Gas Processing. PETROFED Seminar, Safety in Hydrocarbon Sector
Drilling to Dispensing, New Delhi, Aug 12, 2010
3] General Safety Design and Features, Arrow Energy.
4] Foss, Michelle. LNG Safety and Security, Centre for Energy Economics, November 2006
5] Mishra, Ambrish. Safety and Regulatory Structure for CNG, CNG-H2 Vehicles and Fuels in India.
Dec 10-11
6] Recommended Practices for CNG Fueling Station Design, Construction and Operation, NGV
Technology Forumn.