Gas Cargoes

7/29/2019 Gas Cargoes

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LPG / LNG

A liquefied gas is the liquid form of a substancewhich at normal ambient temperatures &atmospheric pressure, would be a gas.

LPGthe generic term for propane, butane &

mixtures of the two.

LPG obtained from

Crude oil processing in refineries

Chemical plant by-products

LNG obtained from

Natural gas streams

Large oil fields


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Ship Types

LPG / Chlorine

Fully pressurisedSpherical tanks

Cylindrical tanks


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Ship Types

LPG / LEG / Chemical gases

Semi-pressurised ships

Spherical tanks

Cylindrical tanks

Lobe tanks


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Ship Types

LPG / LEG / LNG

Fully refrigerated ships

Spherical tanks

Membrane tanks

Semi-membrane tanks

Independent tanks

Integral tanks


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Semi-Refrigerated LPG


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Fully Refrigerated LPG


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Fully Refrigerated LNG


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Membrane Tank


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The Gas Carrier Codes


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The I nternational Code for the Construction

& Equipment of Ships Carrying Liquef ied

Gases in BulkIGC Code

Ships built after June 1986

Made mandatory by SOLAS Ch.VI I

International Certificate of Fitness


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The Code for the Construction & Equipmentof Ships Carrying L iquef ied Gases in Bulk

Gas Carrier (GC) Code

Ships built between 1976 & 1986 NOT mandatory

Implemented into national law by many

countries Charterers would expect compliance

Certificate of Fitness


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The I nternational Code for Existing Ships

Carrying Liquef ied Gases in Bulk

Existing Ship Code

Ships built before 1977

Completed in 1976 after GC Code written

IMO recommendation for older ships

Charterers / terminal expect compliance

Certificate of Fitness


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IGC Code - Ship Types

Type 1G

Designed with maximum preventative measures

Type 2G Designed with significant preventative measures

Type 2PG

As above but LOA < 150m, tanks designed for > 7 bar

pressure and above

550

Type 3G

Designed with moderate preventative measures


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Ship Arrangements

Gas-Dangerous Spaces

Spaces where gas-safe conditions are not assured

Enclosed spaces outside cargo area containing

cargo piping

Cargo containment systems and piping

Hold spaces

Pump rooms & compressor rooms


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Ship ArrangementsGas-Dangerous Zones

Zone on the open deck within 3m of: -

Cargo tank outlet

Vapour outlet

Cargo pipe flange

Cargo pipe valve

Entrances or vents to pump or compressor rooms


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Ship ArrangementsGas-Dangerous Zones

Open deck over cargo areas

3m fwd & aft of cargo areas on open deck

2.4m above weather deck

Within 2.4m of exposed cargo containment system

Spaces containing cargo pipes

Enclosed/semi-enclosed space opening into a gas

dangerous space or zone


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INERTING


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INERTING

GASSING UP li id f h


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GASSING UP - liquid from shore

GASSING UP f h


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GASSING UP - vapour from shore

COOLDOWN li id f h


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COOLDOWN - liquid from shore

LOADING ith t li


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LOADING - with vapour return line

LOADING ith t t li


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LOADING - without vapour return line

LOADED PASSAGE li


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LOADED PASSAGE - cooling

LOADED PASSAGE diti i


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LOADED PASSAGE - conditioning

DISCHARGING i h li


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DISCHARGING - without vapour return line

DISCHARGING ith t li


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DISCHARGING - with vapour return line

LIQUID FREEING


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LIQUID FREEING

BALLAST PASSAGE


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BALLAST PASSAGE

PURGING vapour from shore


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PURGING - vapour from shore

New cargo

vapour

Old cargo

vapour

INERTING to displace cargo apo rs


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INERTING - to displace cargo vapours

AERATION gas freeing


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AERATION - gas freeing


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HEALTH HAZARDS

TOXICITY

ANAESTHESIA

ASPHYXIA

FROSTBITE


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Health Hazards of Specific Cargoes

Ammonia TLV 25 ppm

Effects of L iquid Effects of Vapour

On Eyes Permanent damage

Frostbite

Irritationburning

Frostbite

On Skin Severe chemical burnsFrostbite

IrritationburningFrostbite

Skin Absorption Not absorbed

I ngestion Very harmful

Inhalation Convulsive coughing

Lung damage

Heart failure & cessation of

breathing


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Butadiene TLV 10 ppm


On Eyes Moderate irritation

Can cause damage

Moderate irritation

On Skin Moderate irritation

Superficial frostbite if

contact prolonged

May cause frostbite

Skin Absorption No hazard

I ngestion No known hazard

Inhalation Respiratory tract irritationHeadache, dizziness,

anaesthesia

Impairs central nervous system

Liver disorder

Carcinogenic


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Chlorine TLV 0.5 ppm


On Eyes Severe chemical & coldburns in small amounts

Severe irritation & burning

On Skin Severe chemical & coldburns even through normal

clothing

Severe irritation & burning

Skin Absorption Toxic & corrosive acidsformed with skin moisture

I ngestion Not pertinent

Inhalation Coughing, choking, sneezing,copious salivation, excitement

Bronchitis, teeth erosion,

inflammation of mucuous

membranes


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Sulphur Dioxide TLV 2 ppm


On Eyes Severe burns

Frostbite

Irritation & inflammation

On Skin Severe burns to moist areas

Frostbite

Irritation of moist skin in high

concentrations

Skin Absorption Not absorbed

I ngestion Severe internal burning

Inhalation Burning of respiratory tract

Severe choking

Oedema

Dizziness

Fatal respiratory paralysis


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First-Aid Treatment

Cargo Data Sheets Medical First Aid Guide

First-Aid Equipment IGC CodeChapter 14

stretcher

resuscitation equipment

antidotes

CARGO DATA SHEETS


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CARGO DATA SHEETSEmergency (first-aid) Procedures

AMMONIA PROCEDURES

L iquid in Eye DO NOT DELAY

Flood with fresh water or solution of distilled water & 2.5%

borax and 2.5% boric acid

Continue flooding for at least 30 minutes

Obtain medical assistance as soon as possible

L iquid on Skin DO NOT DELAY

Remove clothing & flood area with water for at least 15

minutes. Apply wet compress of distilled water & 2.5%

borax and 2.5% boric acid. Do not rub. Immerse frost-bitten

area in warm water until thawed. Obtain medical assistanceas soon as possible.

Vapour I nhaled REMOVE VICTIM TO FRESH AIR

Remove clothing. Mouth warm and still. Obtain medical

assistance as soon as possible.


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REACTIVITY

Cargo may react with:- Water

Air Itself

Other cargoes

Other materials


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REACTIVITY

Reactions may result in:- Toxic vapour emission

Heat generation Explosion

Corrosion


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REACTION WITH WATER

Hydrate Formation HYDRATE

crushed ice or slush-like substance

May be caused by:- high dew point of purge vapours

water in cargo system prior to loading

water dissolved in the cargo (some LPGs) May cause seizure of pumps & equipment failure


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REACTION WITH AIR

Formation of unstable oxygencompounds

May cause explosion Inert gas blankets

Shippers inhibitor added


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SELF-REACTION

Polymerisation Initiated by small quantities of other cargoes

Catalyst may be presence of certain metals

Heat produced which accelerates reaction

Butadiene

Isoprene

Vinyl chloride monomer (VCM)

Some cargoes cannot be inhibited Ethylene oxide

Propylene oxide


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REACTION WITH OTHER CARGOES

Separate piping system

Separate ventilation system

Separate refrigeration system Compatibility charts consulted

Cargo data sheets consulted

Effective purging prior to change of cargo


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REACTION WITH OTHER MATERIALS

Materials in cargo system

Poor quality purge vapours

Consult cargo data sheets Effective stowage plan

High quality IG (CO2 content)

Prevent contamination with machinery oil


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CORROSIVITY

Some cargoes & inhibitors may be corrosive

Cargo systems & human tissue at risk

Cargo system materials as per IMO Codes Refer to cargo data sheets

Documents

Gas Cargoes