4.4.1 INTRODUCTION
Chemical hazards are found in many areas on Das Island. Chemicals with hazardous qualities are used in the production processes and in construction and maintenance at various locations. The range of hazardous chemicals includes additives, reagents, by-products, wastes and those used in construction and maintenance processes such as lubricants, sealants, cleaners, protective coating, building/ insulation materials,
welding/soldering/bonding consumables, pesticides, etc.
Products that are purchased and brought to Das Island need to be carefully controlled.
4.4.2 DEFINITIONS Hazardous Substance.
This term is used to denote any of the following:
· Chemicals - elements and compounds or formulated mixtures of those in gaseous, liquid or solid state, packaged or in bulk.
· Explosives
· Radioactive substances
Hazardous substances can be classified by the effects they produce:
· Acute lethal effects
· Non lethal reversible effects
· Severe effects after prolonged exposure
· Irritancy affecting the skin and lungs
· Sensitisation causing long term allergic reactions.
· Carcinogenic, which may induce or increase the frequency of cancer
· Teratogenic, which is having a damaging effect on the embryo
· Mutagenic, which is alteration of the genetic programme of a person.
· Corrosive, that is capable of tissue damage by corrosion or burning.
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4.4.3 RESTRICTIONS
Unnecessary procurement, storage and handling of hazardous substances must be avoided or eliminated.
A hazardous substance must not be introduced to an ADGAS workplace unless:
· Its use, presence or production is essential and there is no alternative product or process available that is less hazardous but otherwise equivalent.
· An approved Material Safety Data Sheet (MSDS) is available to those handling or using the material, before exposure.
· All statutory and ADGAS requirements can be met for:
o safe handling and health protection o packaging
o labelling o transport o storage
o emergency procedures
o waste disposal and environmental protection
In particular, those directly handling possibly hazardous substances must not do so until they have satisfied themselves that they have identified the material, and if it is classified as hazardous, they have established the practices to be adopted.
4.4.4 FLAMMABILITY
An understanding of the following terms is important in the LNG industry:
Flash point - is the lowest temperature at which vapour is given off from a material in sufficient quantities that mixed with air will ignite in the presence of a flame or other direct ignition source but will not sustain combustion.
Flammable - having a closed cup flash point below 37.8°C .
Combustible - will continue to burn in air after the heat source has been removed Non Combustible - combustion ceases when the heat source is removed
Explosive Clouds/Mists - finely dispersed particles or droplets in air creating conditions for an explosion.
Auto-ignition Temperature - is the lowest temperature at which a substance will ignite and sustain combustion when mixed with air without the presence of a spark or flame.
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Explosive Limits - or flammable limit, relates to the range in which a mixture of vapour (gas, mist or powder) with air can burn on ignition. Gas and vapour concentrations are given in percent by volume in air and powdered substances in grams per cubic metre.
Lower Explosive Limit (LEL). The minimum percentage of a vapour which in air will support ignition. Lower percentages will not ignite.
Upper Explosive Limit (UEL): The maximum percentage of a vapour which in air will support ignition. Higher percentages will not ignite.
4.4.5 HEALTH HAZARDS
The form of exposure to harmful substances can be categorised in several ways depending on the means of contact, i.e. skin contact, inhalation, etc.
The effects of the substance can be categorised in varying degrees of either irritation to the body or toxicity (poisoning).
4.4.5.1 INHALATION
Irritation can range upwards from mild discomfort to laboured breathing and fluid in the lungs.
Toxic effects are measured on the LC 50 scale (lethal concentration), based on animal experiments. The level of toxicity is given in parts per million (PPM) concentration in air ranging from 10,000ppm and above as non toxic, with up to 100ppm as highly toxic. The lower figure represents the more dangerous level of toxicity.
Asphyxiation, caused by lack of oxygen and high background concentrations of inert gases (CO2 and N2) can cause suffocation due to impaired respiration. The minimal oxygen content in breathing air is 18% by volume at normal pressure.
Sensitisation may be caused in certain persons by repeated exposure causing an allergic type asthmatic bronchitis.
4.4.5.2 SKIN
Irritation degrees range from minor discomfort up to blistering or full depth skin loss as when in contact with strong acids and alkalis. Dermatitis may result from defatting of the skin from contact with organic solvents. Repeated contact may also cause allergic skin reactions.
Toxic effects result from a substance being absorbed through the skin. Degrees of toxicity are based on the LD 50 scale (lethal dose) given as mg/kg of body weight.
Toxicity ranges from 350mg/kg which is slightly toxic up to 50mg/kg or less in the highest range of toxicity.
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4.4.5.3 EYES
Irritation from contact with chemicals can range from mild discomfort up to permanent eye damage and loss of sight as with the effect of concentrated acid or alkali.
4.4.5.4 INGESTION
This is an unlikely route for the entry of occupational chemicals. Ingestion can occur however, in small and significant quantities by means of poor hygiene with meals, smoking, or from airborne particles swallowed and accumulating in the body.
Irritation can range from minor discomfort up to severe tissue loss and scarring in the mouth, throat and stomach caused by swallowing strong acid or alkali.
Toxic effects of various substances ingested are measured on the LD (Lethal dose) scale and given as mg/kg of body weight.
Degrees of toxicity range from slight toxicity at 500mg/kg and above, up to highly toxic at 50mg/kg or less.
The preceding information is based on the more acute forms of response to irritants or toxic agents. Long term effects are a separate study, but may result from exposure to common agents including dusts, welding, soldering and cutting fumes, smoke, solvents, paint polymers and cleaning agents and others.