The majority of paints contain flammable organic solvents. As soon as a paint container is opened, solvent vapours are released.
The flash point is the lowest temperature at which a liquid gives off sufficient vapour to form a flammable mixture in contact with air.
If the flash point of the paint is lower or close to the ambient air temperature there is a very considerable risk of fire or explosion. It only needs a spark or flame to set it off. If the flash point exceeds the ambient air temperature there is still a risk of fire. Therefore no naked flames, cigarettes or matches should be allowed near the area where paint is being applied or stored. Precautions should also be taken to avoid sparks caused by metal to metal contact or from electrical appliances.
If a fire involving paint does occur:
If paint is spilt the following precautions should be taken:
It is recommended that the following precautions should be taken to prevent paint coming into contact with the skin and eyes:
Remember the object is to avoid skin contact. If your clothes become soaked in paint, change them immediately and thoroughly wash the affected garments with soap and water.
The inhalation of solvent fumes, dust, paint vapours must be avoided. Please follow these precautions listed.
Remember solvent fumes are heavier than air, they push breathable air upwards. They can flow down drains or ventilation ducts.
To prevent the inhalation of spray mists:
Additional information is available from the Health Department on the safe handling and application procedures for isocyanate containing products.
Food and drink should not be consumed, stored or prepared in areas where paint is stored or being applied.
In the case of accidental paint ingestion, medical attention should be obtained at once.
It is the purpose of this note to establish the minimum standards of hygiene and protection for personnel applying paints in the surface coatings industry. It must be recognised that in a progressive society, improvements in the quality and application of paints are inevitable, resulting in the better protection of steel. Older slower methods of paint application are giving way to modern, faster techniques, and it is important to carefully study and overcome any health hazards, which may result from these newer methods. It is not the purpose of this manual to spread alarm to the industry. We are well aware that vast quantities of paint have been, and are being applied to steel without any serious harm occurring to painters, who often have very rudimentary or no protection at all. We do, however, recommend that our advice be carefully studied as it is intended to improve the hygiene and in some cases, the safety of painters using older conventional paints as well as the more modern coatings. These recommendations are meant to supplement and not replace any special legal regulations in any country regarding the application of surface coatings.
Application of paint by airless spray is becoming increasingly popular. This rapid method of paint application produces fine paint mists which in addition to having a nuisance value to workers, may in the case of some paints present a respiratory health hazard. Laboratory and field trials have shown that the mist, other than isocyanate based, is essentially a dust problem that can be satisfactorily overcome by the use of a suitable respirator with a dust cartridge to British Standard Specification 2091 (type B) and pre-filter, or similar national standard specification. Other protective equipment necessary includes eyeshields, head cover, rubber gloves and overalls.
High velocity flow rates of paint and cleaning solvents in airless spray application will cause a buildup of static electricity, particularly in dry weather, resulting in a high voltage spark discharge. To eliminate fire risk from this cause, earthing of the airless spray gun and unit is essential. While they hold the gun, this will also help to earth the painter's protective clothing, which can also build up electrical charge. Rubber and plastic garments are particularly prone to this effect.
With brush or roller application, the precautions required are minimal, there being no respiratory hazard associated with these traditional methods. Discomfort due to eye splashes is perhaps the most important mishap that can occur, this discomfort can be eliminated by the use of inexpensive eye shields. Hand protection is also desirable, plastic or rubber gloves being suitable for this purpose.
Some of these are miscible with some paint solvents and it is possible that they may assist organic poison absorption through the skin and for this reason most authorities are against their use. However it is difficult to remove dried paint from the skin using only soap and water without the prior use of barrier creams, and to leave paint on the skin also cannot be considered satisfactory. The use of a proprietary industrial skin cleanser followed by a skin conditioner (to replace lost natural oils) is often the best way of overcoming these skin cleaning difficulties. If painters insist on pre-treating their skin before spraying then a non-greasy barrier cream should be supplied. Greasy substances such as vaseline or petroleum jelly should not be used.
The foregoing recommendations can be considered as the minimum standards consistent with hygiene and safety. However, more sophisticated but expensive equipment is available in the field of respiratory protection, and there are other protective measures which can add to the comfort of the painter.
The following are a few examples:
Air line respirators:
Although expensive, the advantages of an air line respirator are obvious. Clean fresh air is supplied to workpeople through an air hose, making them independent of any polluted atmosphere in which they may have to work.
In situations where solvent odour becomes objectionable, a "light fume" cartridge can be added to the respirator in a duplex arrangement. This arrangement is intended for outdoor use and it must always be remembered that cartridge respirators must never be used in atmospheres deficient in oxygen.
Disposable overalls and head cowls:
The overalls are available as coats to be worn over normal overalls – the head cowls cover the whole of the head apart from a 15cm diameter circle for the face. Both are made of a fibre composition, which affords excellent protection against spray and splashes.
The notes listed below are designed to provide help and guidance when modern Protective Coatings are being used in different environments. These notes are not intended to be a complete treatise on the subject of safety during painting but are designed to make one aware of some of the dangers involved. Further information may be made available if required by contacting our local representatives. The two notes presented cover: (1) The interior painting of tanks, (2) Exterior painting.
A high proportion of tank coatings applied throughout the world contain flammable organic solvents, which can form explosive mixtures with air. Refer to AS/NZS 2865:2001 Safe Working in a Confined Space for safety precautions to be taken while applying these coatings.
Attention must be given to the following points:
The key factors in preventing explosion or fire are:
Any organic based coating could, merely by the normal process of drying, give off sufficient solvent vapour to produce an explosive mixture in a tank when the vapour concentration reaches or exceeds 1% by volume in air. However, at 1% these solvents produce an intolerably unpleasant odour, often with irritating skin effects and smarting of the eyes. These symptoms should be taken as a warning sign that better ventilation is needed. 0.2% solvent vapour in air is normally recommended to give a five-fold safety margin and at this concentration NO EXPLOSION CAN OCCUR.
Both air blowing and extraction methods of ventilation have been suggested but experience has shown that of the two methods, blowing is more efficient. Extraction tends to produce channelling with smooth air flow and dangerous pockets of solvent vapour. Blowing causes turbulence, which disperses solvent pockets.
For individual tanks the blowing air is trunked into the coaming down to a depth of 2.5-3 metres in a 12 metre tank. This prevents the blowing air immediately returning through the coaming without sweeping the tank. The geometry and size of tanks makes each one a separate problem and it is essential to check that the ventilation arrangement, fan output, etc. is suitable before painting commences.
FORE AND AFT PEAKS AND DOUBLE BOTTOMS of ship tanks require special attention. Because of their construction, adequate ventilation is difficult, resulting in a rapid build up of solvent vapours to toxic and explosive concentrations. It is necessary to have a responsible standby man at the tank opening to keep a "head count" of painters and other workers and to ensure no interruption of essential services, i.e. air supplies and electricity.
No ventilation system can reduce solvent vapour levels to below the Threshold Limit Values for solvents in tank coating procedures. Painters must therefore wear air fed hoods or pressure fed masks with additional eye protection. Normal protective clothing must be worn, e.g. overalls, gloves and non-spark footwear.
If proper protective clothing has been worn, e.g. overalls, gloves, airline hood etc., no difficulty should be experienced from skin irritation. Any small areas not protected by clothing, such as wrists or neck can be treated with a non-greasy barrier cream. Petroleum jelly is not recommended. Areas of skin accidentally contaminated with paint should be cleaned with a proprietary industrial skin cleaner then thoroughly washed with soap and water. Skin conditioners designed to replace the natural oils in the skin can be used with advantage.
It is believed that the foregoing notes will provide a practical basis for the safe painting of tanks. There are however a number of technical terms and principles, which provide the scientific basis of these notes and which are often quoted (or misquoted) in practice. The following simple definitions should help clear up any misconceptions.
The lowest temperature at which a liquid gives off vapour sufficient to form an inflammable mixture in contact with air. It is a rather rough yet quick way of measuring the relative combustibility of volatile liquids and, in turn, determines the appropriate temperature below which combustibles may be stored and used without creating explosive atmospheres. The flashpoint is always determined in a standard apparatus.
Flashpoint and lower explosive limit are interconnected. The flashpoint is the temperature at which a liquid gives off sufficient vapour into a fixed volume of air so that when a naked flame is applied the mixture will ignite. The quantity (%) of vapour in the mixture when ignition occurs is the lower explosive limit for that particular solvent. This means that at all temperatures below the flashpoint of a solvent the quantity of vapour it can give off into the atmosphere must be less than the lower explosive limit. This simple guide to the volatility of solvents is, however, complicated by the presence of paint spray and solvent mist (liquid particles) in tank atmospheres. If particulate spray is present it will also have a lower explosive limit, which is not dependent on the flashpoint of any solvent mixture present.
Threshold limit values refer to airborne concentrations of substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect. The TLV is expressed in milligrams per cubic metre (mg/M3) of air and in parts per million; that is parts of gas per million parts of air. The TLV's for paint solvents are very much lower than safe explosion limit concentrations and in ship tanks it is totally impractical to attempt to ventilate to below the TLV for a solvent mixture. Painters must be provided with suitable breathing apparatus.