CHEMICAL HAZARDS ON CHEMICAL TANKERS- CAPT AJIT VADAKAYIL
Personal Protective Equipment - The items listed are those recommended by (a) manufacturers, either in technical bulletins or in Material Safety Data Sheets, (b) the Chemical Manufacturers Association, or (c) the National Safety Council, for use by personnel while responding to fire or accidental discharge of the chemical. They are intended to protect the lungs, eyes, and skin. Safety showers and eyewash fountains are considered to be important protective equipment for the handling of almost all chemicals; they are not usually listed.
Symptoms Following Exposure - These are brief descriptions of the effects observed in humans when the vapor (gas) is inhaled, when the liquid or solid is ingested (swallowed), and when the liquid or solid comes in contact with the eyes or skin.
Treatment for Exposure - “First-aid” procedures are recommended. They deal with exposure to the vapor (gas), liquid, or solid and include inhalation, ingestion (swallowing) and contact with eyes or skin. The instruction “Do NOT induce vomiting” is given if an unusual hazard is associated with the chemical being sucked into the lungs (aspiration) while the patient is vomiting. “Seek medical attention” or “Call a doctor” is recommended in those cases where only competent medical personnel can treat the injury properly. In all cases of human exposure, seek medical assistance as soon as possible.
Threshold Limit Value – Time Weighted Average -The Threshold Limit Value Time Weighted Average (TLV-TWA) is usually expressed in units of parts per million (ppm) - i.e., the parts of vapor (gas) per million parts of contaminated air by volume at 25oC (77oF) and one atmosphere pressure. For a chemical that forms a fine mist or dust, the concentration is given in milligrams per cubic meter (mg/m3). The TLV is defined as the concentration of the substance in air that can be breathed for five consecutive eight-hour workdays (40-hour work week) by most people without adverse effect (American Conference of Governmental Industrial Hygienists, “Threshold Limit Values for Substance in Workroom Air, Adopted by ACGIH”). As some people become ill after exposure to concentrations lower than the TLV, this value cannot be used to define exactly what is a “safe” or “dangerous” concentration.
No entry appears when the chemical is a mixture; it is possible to calculate the TLV for a mixture only when the TLV for each component of the mixture is known and the composition of the mixture by weight is also known.
Threshold Limit Value - Short-Term Exposure Limits - The parts of vapor (gas per million parts of contaminated air by volume at 25oC (77oF) and one atmosphere pressure is given. The limits are given in milligrams per cubic meter for chemicals that can form a fine mist or dust. The values given are the maximum permissible average exposures for the time periods specified.
Threshold Limit Value – Ceiling Value – The parts of vapor (gas per million parts of contaminated air by volume at 25oC (77oF) and one atmosphere pressure is given. The limits are given in milligrams per cubic meter for chemicals that can form a fine mist or dust. The values given are for a concentration that is not to be exceeded at any time.
Toxicity by Ingestion - The Grade and corresponding LD50 value are those defined by the National Academy of Sciences, Committee on Hazardous Materials, “Evaluation of the Hazard of Bulk Water Transportation of Industrial Chemicals, A Tentative Guide,” Washington, D.C., 1972. Data were also collected from other sources and converted to the appropriate Grade before entry in this manual. The term LD50 signifies that about 50% of the animals given the specified dose by mouth will die. Thus, for a Grade 4 chemical (below 50 mg/kg) the toxic dose for 50% of animals weighing 70 kg (150 lb) is 70 X 50 = 3500 mg = 3.5 g, or less than 1 teaspoonful; it might be as little as a few drops. For a Grade 1 chemical (5 to 15g/k g), the LD50 would be between a pint and a quart for a 150-lb man. All LD50 values have been obtained using small laboratory animals such as rodents, cats, and dogs. The substantial risks taken in using these values for estimating human toxicity are the same as those taken when new drugs are administered to humans for the first time.
Toxicity by Inhalation – Similar to the Toxicity by Ingestion entry, except that the route of exposure is inhalation instead of ingestion. Units and definition of units are the same.
Chronic Toxicity - Where there is evidence that the chemical can cause cancer, mutagenic effects, teratogenic effects, or a delayed injury to vital organs such as the liver or kidney, a qualitative description of the effect is given.
Vapor (Gas) Irritant Characteristics - The most appropriate of five statements listed below is given. Source: National Academy of Sciences, Committee on Hazardous Materials, “Evaluation of the Hazard of Bulk Water Transportation of Industrial Chemicals, A Tentative Guide,” Washington, D.C.,1972.)
(1) Vapors are non irritating to eyes and throat.
(2) Vapors cause a slight smarting of the eyes or respiratory system if present in high concentrations. The effect is temporary.
(3) Vapors cause moderate irritation such that personnel will find high concentrations unpleasant. The effect is temporary.
(4) Vapors are moderately irritating such that personnel will not usually tolerate moderate or high concentrations.
(5) Vapors cause severe irritation of eyes and throat and can cause eye and lung injury. They cannot be tolerated even at low concentrations.
Liquid or Solid Irritant Characteristics - The most appropriate of the following five statements is given (same source as 5.8 above):
(1) No appreciable hazard. Practically harmless to the skin.
(2) Minimum hazard. If spilled on clothing and allowed to remain, may cause smarting and reddening of skin.
(3) Causes smarting of the skin and first-degree burns on short exposure; may cause second-degree burns on long exposure.
(4) Fairly severe skin irritant. May cause pain and second-degree burns after a few minutes' contact.
(5) Severe skin irritant. Causes second- and third-degree burns on short contact and is very injurious to the eyes.
Odor Threshold - This is the lowest concentration in air that most humans can detect by smell. The value cannot be relied on to prevent over-exposure, because human sensitivity to odors varies over wide limits, some chemicals cannot be smelled at toxic concentrations, odors can be masked by other odors, and some compounds rapidly deaden the sense of smell.
IDLH Value - The Immediately Dangerous to Life and Health Value - This concentration represents a maximum level from which one could escape within 30 minutes without any escape-impairing symptoms or any irreversible healtheffects. The concentrations are reported in either parts per million (ppm) or milligrams per cubic meter (mg/m3).
OSHA Permissible Exposure Limit – Time Weighted Average – Similar to the definition of the TLV-TWA above, except that this limit has been promulgated by the Occupational Safety and Health Agency.
OSHA Permissible Exposure Limit – Short Term Exposure Limit – Similar to the definition of the TVL-STEL above, except that this limit has been promulgated by the Occupational Safety and Health Agency.
OSHA Permissible Exposure Limit – Ceiling – Similar to the definition of the TVL-Ceiling above, except that this limit has been promulgated by the Occupational Safety and Health Agency.
EPA AEGL – Acute Exposure Guideline information from the Environmental Protection Agency for the specific compound listed in the manual.
Transportation of bulk chemicals do not only require special hardware, but also special crew training, both theoretical and practical, in order for them to understand the characteristics of the various chemicals and be aware of the potential hazards involved in handling them.
Detailed hazards of particular substances are provided in MSDS and in publications such as the, ICS Tanker Safety Guide (Chemicals). The purpose of the following is to provide broad guidance on these hazards, particularly those impacting on health.
Chemical cargoes may present a fire hazard which will be determined by the flashpoint, boiling point, flammability limits and auto-ignition temperature of the product. The marine pollution hazard will be dependent on several factors that include bioaccumulation and the attendant risk to aquatic life or human health or causing tainting to seafood. In addition, release into the marine environment may cause damage to living resources, hazard to human health and consequent reduction of amenities.
The air pollution hazard posed by release into the atmosphere may be categorised by the emergency exposure limit (EEL) of the substance.
Most of the chemicals present more than one hazard to health, for example, it may:
• Be corrosive.
• Be poisonous.
• Produce toxic vapours.
• Pose an asphyxiation hazard.
• Result in long-term damage to eyes or the nervous system.
• Have long-term carcinogenic effects.
Toxicity may be described as the ability of a substance to cause damage to living tissue, impairment of the central nervous system, severe illness or, in extreme cases, death when inhaled, ingested, or absorbed by the skin. The amounts required to produce these results vary widely with the nature of the substance and the time of exposure to it. Toxicity is divided into two main groups; “acute” which refers to exposure of a short duration, i.e. a single brief exposure, and the “chronic” toxicity refers to exposure of long duration, i.e. repeated or prolonged exposures. Toxicity is objectively evaluated on the basis of test dosages made on experimental animals under controlled conditions.
Prevention from exposures is achieved by a combination of preventing toxic fumes or liquid from contaminating the workplace and the use of Personal Protective Equipment.
Asphyxia can be described as a condition caused by lack of air (oxygen) i.e. suffocation. Any vapour may cause asphyxiation, whether toxic or not. Danger areas are cargo tanks, void spaces, double bottoms, pump rooms, peaks etc. and before entering these spaces The Company’s Enclosed Space Entry procedures must be observed.
Certain vapours have an anesthetic effect and may cause loss of consciousness due to its effect on the nervous system. Anesthetic vapours could be both toxic and non toxic.
Exposure may be either acute or chronic. With acute exposure, the victim is subjected to a one-off high level dose and the symptoms are usually immediately apparent, although there can be a delayed reaction. The damage caused may be irreversible, even with treatment.
Chronic exposure is associated with a relatively low level of exposure over a period of time. Symptoms may not be apparent until many years later, which in some cases, could be over 30 years after exposure ceases.
Exposure to the product may be by inhalation, skin absorption or ingestion. Inhalation of vapour or mist is by far the most likely route for harmful substances to enter the body.
The effect of exposure will depend upon the toxicity of the vapour, the level of contamination and the volatility of the product. Exposure to the vapour may cause a variety of effects that could include systemic poisoning, irritation of the nose, throat and respiratory system and even asphyxiation.
Absorption may be directly through skin contact and any physical injuries, such as cuts or abrasions, will serve to increase the absorption rate. Exposure may cause skin irritation which, in its mildest form may result in dermatitis, and systematic effects.
Ingestion may be caused, for example, by accidentally swallowing a chemical when splashed by it. Some liquids have corrosive properties such that if they come into contact with the skin, they may completely or partly destroy living tissue, causing acute pain. Others, although only causing slight skin irritation at the outset, can eventually result in severe damage to the eyes and other mucous membranes.
There are various types of respiratory protection equipment available, ranging from simple dust masks to more complex types of masks. It is essential that the correct type of mask is worn for the specific task to be carried out.
Note that respirators do not protect the user in an oxygen deficient atmosphere and they do not necessarily protect against all gases that may exist on a ship. Some types of respirator (filter canister type masks) are designed to protect from specific chemicals and are used sometimes in the petro-chemical industry ashore. However, these are not suitable for ship use and prohibited onboard Company vessels.
The only sure way that you can guarantee the air you are breathing is safe, is to use a compressed air breathing apparatus set filled by a dedicated compressor with a clean air certificate.
Filter masks should be used only in areas where the air contains at least 20% by volume of oxygen.
It is also important to understand that a filter mask alone will not give adequate protection. It shall be noted that a chemical may be both toxic and explosive/flammable.
Threshold Limit Value (TLV):
TLV refers to the maximum concentration of gases, vapours, mist or sprays to which it is believed that nearly all persons may be repeatedly exposed day after day without adverse effects. TLV is stated as Time Weighted Average (TLV-TWA), Short Term Exposure Limit (TLV-STEL) and Ceiling (TLV-C): usually expressed in parts per million (ppm). Refer to ISGOTT for more details.
Vapour given off by a flammable liquid will burn when ignited provided it is mixed with certain proportions of air. If the vapour mixture is too lean or too rich it will not burn. The range in which it will burn is called the flammable range, and the limits are called the lower flammable limits (LFL) and the upper flammable limits (UFL). See definitions carried in Section 1 of these operating instructions for further details.
A flammable vapour also needs Oxygen in order to burn, typically in excess of 11 percent for hydrocarbon vapours. In addition a flammable liquid must be at a temperature high enough to give off sufficient vapour in order to ignite (the Flash Point). For the purpose of safe handling procedures, the flammability characteristics of various products are divided into three broad categories:
Flammable cargoes------------ flash point not exceeding 60°C
Combustible cargoes-----------flash point exceeding 60°C
Non-combustible cargoes------cargoes which have no flash point
Chemicals may react in a number of ways; with water, with itself, with air, with other chemicals or with other materials.
The most common form of self-reaction is polymerisation. Polymerisation may be a slow natural process which only degrades the product without posing any safety hazards, or it may be a rapid exothermic reaction with a large amount of heat build-up and gases evolved. Such a reaction is called a run-off polymerisation and poses a serious danger to both the ship and its personnel.
Products that are self-reactive are inhibited with a stabiliser to prevent self-reaction. The action to be taken in case of a polymerisation situation should be covered by the ship’s emergency/contingency plan.
• Reaction with water
Certain cargoes react with water, most noticeable the isocyanates, in a way that could pose a danger to both the ship and its personnel. These cargoes are carried under inert condition, see chapter 9 in the IBC code. Other cargoes react with water in a slow way that poses no safety hazards, but the reaction could cause chemicals that may damage equipment and/or tank materials.
• Reaction with air
Certain cargoes may react with air to form unstable oxygen compounds (peroxides) which, when allowed to build up, could cause an explosion. Such cargoes are either inhibited by an anti-oxidant and/or carried under inert condition.
• Reaction with other cargoes
Certain cargoes react dangerously with one another. Such cargoes should be stowed away from each other (not adjacent) and prevented from mixing by using separate cargo and vent lines.
The master must ensure that cargoes stowed adjacent to each other are compatible, and should consult the USCG CHRIS compatibility guide (Section 16) prior to loading.
Reaction with other materials:
The materials of construction must be compatible with the cargo to be carried. Some materials may react with the product and trigger a self- reaction within the product, some alloys will react in a non hazardous way, but render the product unusable or in case of an edible product, inedible. See the IBC code.
Acids, anhydrides and alkalis are among the most common carried corrosive substances. They can rapidly destroy human tissue and cause irreparable damage. They can also corrode normal construction materials, and create a safety hazard to the ship. Acids in particular react with most metals evolving hydrogen gas, which is highly flammable. As to suitable materials of construction see IBC code.
Handling of these substances should only be done wearing suitable Personal Protective Equipment.
Most animal and vegetable oils undergo decomposition, this process, known as putrefaction, generates obnoxious and toxic vapours and deplete the oxygen in the tank. Tanks that have contained such product must be properly ventilated and the atmosphere tested prior to tank entry. This is especially important prior sending personnel into the tank for sweeping purposes.
Strict compliance with the tank entry procedures will apply.
Coconut and Vegetable Oils:
In addition to putrefaction, the above types of oil can have hazards associated with the production of Carbon Monoxide (CO). These dangers are heightened during heating and the final stages of discharge when CO levels have been known to reach in excess of 3,000ppm. As a result, it is essential that before entering a tank for either “squeezing” the last remaining cargo or for tank cleaning that the following precautions are taken.
The atmosphere of the tanks is monitored regularly throughout discharge for the presence of CO. Temperatures should also be taken as excessive temperatures will assist in the production of CO.
The eight-hour safe exposure limit for CO is given as , 30PPM although short-term exposure (15 minutes) of up to 200ppm can be allowed under exceptional circumstances. CO is toxic by inhalation and can cause serious damage to heath. Accordingly, a meter, capable of measuring these limits, must be on board. Full enclosed space entry procedures as detailed in the SEM must also be followed with additional checks made for CO. Failure to follow these precautions may result in fatalities.
Reactivity with Water - The term “No reaction” means that no hazard results when the chemical reacts or mixes with water. Where a hazard does result, it is described.
Reactivity with Common Materials - This is limited to hazardous reactions with fuels and with common materials of construction such as metal, wood, plastics, cement, and glass. The nature of the hazard, such as severe corrosion or formation of a flammable gas, is described.
Stability During Transport - The term “Stable” means that the chemical will not decompose in a hazardous manner under the conditions of temperature, pressure, and mechanical shock that are normally encountered during shipment; the term does not apply to fire situations. Where there is a possibility of hazardous decomposition, an indication of the conditions and the nature of the hazard is given.
Neutralizing Agents for Acids and Caustics - In all cases involving accidental discharge, dilution with water may be followed by use of the agent specified, particularly if the material cannot be flushed away; the agent specified need not necessarily be used.
Polymerization - A few chemicals can undergo rapid polymerization to form sticky, resinous materials, with the liberation of much heat. The containers may explode. For these chemicals the conditions under which the reaction can occur are given.
Inhibitor of Polymerization - The chemical names and concentrations of inhibitors added by the manufacturer to prevent polymerization are given.
Aquatic Toxicity - The form of data presentation used by the Environmental Protection Agency's “Oil and Hazardous Material-Technical Assistance Data System (OHM-TADS)” is used here. Reading from left to right and separated by slashes (/) are the following data:
Concentration in parts per million by weight (or milligrams per liter) at which the chemical was tested;
Time of exposure in hours;
Name of the aquatic species studied;
Effect observed; LC50 means that approximately 50% of the fish will die under the conditions of concentrations and time given. TLm (Median Tolerance Limit) means that approximately 50% of the fish will show abnormal behavior (including death) under the conditions of concentrations and time given; the term EC50 (Effective Concentration50) is used sometimes instead of TLm;
The kind of water used in the test (fresh or salt)
Some chemicals have been tested with many species of fish. Where the data were available, the
data sheet cites one illustrative test in fresh water and one in salt water.
Waterfowl Toxicity - Very little information is available. In a few cases there is entered the LD50 value, which indicates the dose (in milligrams per kilogram of body weight) that is lethal to about half the waterfowl tested.
Biological Oxygen Demand (BOD) - Also called “biochemical oxygen demand,” this is a standard way of describing how much oxygen dissolved in water is consumed by biological oxidation of the chemical during the stated period of time. The unit lb/lb indicates the pounds of oxygen consumed by each pound of chemical during the time stated. When given in percent, the values indicate the pounds of oxygen consumed by each 100 pounds of chemical during the time stated. If the percentage is followed by “(theor.)”, it indicates the pounds of oxygen theoretically required to completely oxidize 100 pounds of the chemical.
Food Chain Concentration Potential - If the chemical is consumed by fish, marine plants, waterfowl, etc., that are in turn eaten by other species, the substance may accumulate and ultimately be consumed by humans. Where this occurs, an indication of the potential hazard and its significance is given.
GESAMP Hazard Profile – A composite list of hazard profiles evaluated by the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP). A summary of the legends used in the profile follows.
Bioaccumulation and Tainting
+ Bioaccumulated to significant extent and known to produce a hazard to aquatic life or human health.
Z Bioaccumulated with attendant risk to aquatic organisms or human health, however, with short retention of the order of one week or less.
T Liable to produce tainting of seafood.
No evidence to support one of the above ratings (+, Z, T)
5 Damage to Living Resources, Extremely toxic 96 hr LC50 less than 0.01 mg/l
4 Highly toxic less than 1 mg/l
3 Moderately toxic 1-10 mg/l
2 Slightly toxic 10-100 mg/l
1 Practically nontoxic 100-1000 mg/l
0 Non-hazardous greater than 1000 mg/l
D Substance likely to blanket the sea-bed
BOD Substance with oxygen demand
Hazard to Human Health by Oral Intake LD50
4 Highly hazardous less than 5 mg/kg
3 Moderately hazardous 5-50 mg/kg
2 Slightly hazardous 50-500 mg/kg
1 Practically non-hazardous 500-5000 mg/kg
0 Non-hazardous greater than 5000 mg/kg
Hazard to Human Health by Skin and Eye Contact or Inhalation
II Hazardous (severe irritation, strong sensitizer, lung injury, percutaneous toxicity, carcinogenic, or other specific long-term adverse health effect.
I Slightly hazardous (mild irritation, weak sensitizer) Non-hazardous (non-irritant, not a sensitizer)
Reduction of Amenities
XXX Highly objectionable because of persistency, smell or poisonous or irritant characteristics; as a result contaminated beaches liable to be closed; also used when there is clear evidence that the substance is a human carcinogen or that the substance has the potential to produce other serious specific long-term adverse health effects in humans.
XX Moderately objectionable because of the above characteristics, but short-term effects leading only to temporary interference with use of beaches; also used when there is credible scientific evidence that the substance is an animal carcinogen but where there is no clear evidence to indicate that the material has caused cancer in humans, or when there is evidence from laboratory studies that the substance could have the potential to produce other serious specific long-term adverse health effects.
X Slightly objectionable, non-interference with use of beaches.No problem.
Ratings in brackets, ( ), indicate insufficient data available to the GESAMP experts on specific substances, hence extrapolation was required. N – Not applicable (e.g. if gases) Indicates data were not available to the GESAMP Working Group.
Grades or Purity - The grades USP (United States Pharmacopoeia) and CP (chemically pure) are quite pure. Where “Technical” or “Commercial” grades are given, the percent by weight of the pure chemical present is usually indicated.
In a few cases the identity of the major impurities is given. If the properties of the less pure grades differ significantly from those of the pure substance, the differences in properties are described in general terms.
Storage Temperature - The range of temperatures at which the chemical is normally shipped in bulk by water transport is given. “Ambient” means the temperature of the surroundings.
Inert Atmosphere - The terms used are “inerted,” “padded,” “ventilated (forced),” “ventilated (natural),” and “no requirement.” They are given when found in the Code of Federal Regulations, Title 46, beginning in Part 151.05.
IMO Pollution Category – pollution classification applied to this compound by the International Maritime Organization.
Ship Type – The data entry refers to construction and containment requirements for ships being used to transport the chemical in question. The information is taken from the Code of Federal Regulations, Title 46, Part 154.
CHEMICAL FIRE HAZARDS
Flash Point - This is defined as the lowest temperature at which vapors above a volatile combustible substance will ignite in air when exposed to a flame. Depending on the test method used, the values given are either Tag closed cup (C.C.) (ASTM D56) or Cleveland open cup (O.C.) (ASTM D93). The values, give an indication of the relative flammability of the chemical. In general, the open cup value is about 10o to 15oF higher than the closed cup value.
Flammable Limits in Air - The percent concentration in air (by volume) is given for the lower (LFL) and upper (UFL) limit. The values, give an indication of the relative flammability of the chemical. The limits are sometimes referred to as “lower explosive limit” (LEL) and “upper explosive limit” (UEL).
Fire Extinguishing Agents Not to be Used - The agents listed must not be used because they react with the chemical and create an additional hazard. In some cases they are listed because they are ineffective in putting out the fire.
Special Hazards of Combustion Products - Some chemicals decompose or burn to give off toxic and irritating gases. Such gases may also be given off by chemicals that vaporize in the heat of a fire without either decomposing or burning. If no entry appears, the combustion products are thought to be similar to those formed by the burning of oil, gasoline, or alcohol; they include carbon monoxide (poisonous), carbon dioxide, and water vapor. The specific combustion products are usually not well known over the wide variety of conditions existing in fires; some may be hazardous.
Behavior in Fire - Any characteristic behavior that might increase significantly the hazard involved in a fire is described. The formation of dense smoke or flammable vapor clouds, and the possibility of polymerization and explosions is stated. Unusual difficulty in extinguishing the fire is also noted.
Ignition Temperature - This is the minimum temperature at which the material will ignite without a spark or flame being present. It gives an indication of the relative flammability of the chemical. It is sometimes called the “autoignition temperature.”
Electrical Hazard - The ease with which the chemical is ignited by electrical equipment is indicated by the Group and Class assignment made in the National Fire Protection Association, “Hazardous Chemicals Data,” Boston, Mass., 1994 and in “Classification of Gases, Liquids, and Volatile Solids Relative to Explosion-Proof Electrical Equipment,” National Academy of Sciences, 1982. This information is available for relatively few chemicals, so an absence of data does not necessarily mean that the substance is not hazardous in the presence of electrical equipment.
Burning Rate - The value is the rate (in millimeters per minute) at which the depth of a pool of liquid decreases as the liquid burns.
Adiabatic Flame Temperature - The value is the temperature in degrees Fahrenheit of the flame when the material is burned under adiabatic conditions.
Stoichiometric Air to Fuel Ratio - The value is the ratio of air to the compound in question required for stoichiometric combustion. Since it is a ratio, the value is dimensionless.
Flame Temperature - The value is the temperature in degrees Fahrenheit of the flame produced by burning the compound under stoichiometric conditions without any rate controls.
Molar Ratio (Reactant to Product) – The number of moles of products formed, assuming complete combustion of a single mole of the chemical reactant. These ratios were calculated assuming there was sufficient oxygen available and that combustion did, in fact, go to completion.
Minimum Oxygen Concentration for Combustion (MOCC) – Information from NFPA-69 regarding the minimum percentage of oxygen required to support combustion of the subject compound. The results are reported for oxygen diluted with nitrogen (N2) and/or carbon dioxide (CO2).
CAPT AJIT VADAKAYIL
29 years in command