Auto Draft

Managers of petrochemical, refining, power, offshore, pulp and paper and other amenities with intensive scorching processes and piping methods are incessantly challenged with performing all the necessary coatings upkeep work only during periods of outages. Outages are required so that process gear can be correctly maintained and repaired together with cleansing of pipelines and vessels, maintenance and substitute of pumps, motors and valves, upkeep coating operations, and other work that can only be achieved when the operations are shut down.
When coatings work has to be carried out on areas where elevated temperatures are involved, many suppose that the ability must be shut down. This may not be the case.
A question incessantly posed by facility managers is, “Can I do maintenance portray work while the plant is operating?” As described beneath, the reply is, “Yes you possibly can, but there are security and well being points that have to be considered”.
Dangers to personnel have to be managed regardless of when or the place work is performed.
Safety and health concerns
There is a spread of security and well being hazards that have to be thought of on each industrial upkeep painting project, whether or not the coating materials is being applied to hot steel or not. Some of those embrace proper materials handling and storage, fall protection, control of fireside and explosion hazards, and exposure to noise, heavy metals, solvents and other health dangers.
These risks have to be correctly evaluated and managed on each industrial upkeep painting project, no matter when or where the work is performed. While present on any job, when applying specialty coatings to sizzling surfaces, some security and health issues should receive further consideration.
Flammable and flamable liquids in plenty of coatings (solvents) can vaporize and type flammable mixtures in the air, especially when atomized throughout spray application or heated. The degree of hazard is decided by the next:
The auto ignition temperature (AIT) of the coating materials is the only most essential problem when applying coatings to hot working tools. AIT is defined (by the National Safety Council publication Accident Prevention Manual For Business and Industry: Engineering & Technology) as “…the minimal temperature at which a flammable gas-air or vapour-air mixture will ignite from its personal heat supply or contact with a heated floor without the presence of an open spark or flame.”
The concept of flash level as outlined by NFPA 30 is “the minimal temperature of a liquid at which sufficient vapour is given off to type an ignitable mixture with the air, near the surface of the liquid”. In different phrases, the flash level describes the temperature of the liquid that’s high sufficient to generate sufficient vapour to create a flame if a supply of ignition were launched.
For vapours of flammable liquids, there’s a minimum focus beneath which the spread of the flame does not happen when involved with a supply of ignition. This is the Lower Flammable Limit (LFL). There is a maximum focus of vapour in the air above which the unfold of the flame doesn’t happen. This is the Upper Flammable Limit (UFL). The flammable range is between the LFL and the UFL, when the concentration of vapours can help combustion.
If security procedures are followed, outages is most likely not required whereas upkeep is carried out.
Implementing controls
Applying coatings to hot surfaces increases the speed at which the solvents are pushed off. When applying solvent borne coatings to hot surfaces it should be assumed that the focus of vapours within the air might exceed the LFL (at least for a brief while after application). As with coating utility to ambient temperature steel, controls should be applied.
While the LFL is likely to be achieved over a shorter period of time throughout sizzling software of coatings than coatings work performed at ambient circumstances, the resulting fireplace hazard exists in both applications. That is, the fireplace hazard and related controls should be considered for the applying of any solvent-borne flammable coating system, whatever the work surroundings. It should be recognized that the gasoline element of the fireplace tetrahedron will be current in both ‘hot’ and ‘ambient’ environments and fundamental steps should be taken to attenuate unnecessary solvent vapours within the work space. In addition, as outlined later, attention should also be directed to eliminating the remaining component of the tetrahedron – the source of ignition.
Controlling flammable vapours
The gasoline factor of a hearth can be decreased by implementing fundamental controls similar to dealing with and storing flammable liquids in accredited, self-closing containers, maintaining the number of flammable liquids containers in the work area and in storage areas to the minimal needed and inside allowable (regulatory) limits.
Alkaline detergents such as tri-sodium phosphate may be substituted, followed by surface washing with contemporary water or steam cleaning and pH testing of the floor, or non-combustible solvents such as 1,1,1 trichloroethane) for pre-surface preparation solvent cleaning.
Combustible fuel indicators should be used to verify that the concentration of flammable vapours is below the LFL. Combustible fuel indicators must be calibrated in accordance with the manufacturer’s recommendations and should be accredited for use in flammable atmospheres. Operators of the gear have to be educated in correct gear operation.
Secure must be taken within the common work area and the neighborhood of the operator and in areas where there are potential sources of ignition. Typically, units are set to alarm at 10% of the LFL. If the alarm sounds, coatings software work ought to immediately cease until the concentration of flammable vapours is managed. The function of setting the alarm beneath the LFL is to provide a safety factor that leads to control measures being applied earlier than there’s an imminent hazard of fireplace or explosion.
Monitoring of the combustible vapour concentration shall be essential because the effectiveness of natural air flow could also be variable. If control of flammable vapours requires mechanical air flow, an occupational security or health skilled or engineer with experience in industrial air flow should be consulted.
At a minimum, mechanical air flow systems should present sufficient capability to regulate flammable vapours to under 10% of the LFL by either exhaust ventilation to take away contaminants from the work space or by dilution ventilation by way of introduction of fresh air to dilute contaminants. As with combustible fuel indicators, air flow tools should be permitted for safe use in flammable atmospheres. In addition, ventilation tools should be grounded and bonded.
Additional air flow, if wanted, ought to be steady throughout coatings software as concentrations might improve as more surfaces are coated during the course of a piece shift, and especially on scorching surfaces the place the rate of vaporization is higher.
Ventilation throughout coatings utility ought to be steady, especially when engaged on sizzling surfaces.
Sources of Ignition
When applying coatings to sizzling surfaces, the first source of ignition that readily involves thoughts is the warmth from the surface being painted. The AIT of the coating materials is the single most necessary concern when applying coatings to sizzling working equipment. The AIT of a substance or combination is the minimal temperature at which a vapour-air mixture will ignite when in contact with a heated floor, with out the presence of any open spark or flame.
The key to controlling this source of ignition is to verify the surfaces being coated are below the AIT of the coatings being utilized. While surface temperatures could additionally be known/available in many services, all surface areas of the process/piping being painted and/or any equipment adjoining to the items being painted the place overspray may deposit must be measured for actual floor temperature. The outcomes must be compared to the AIT of the coating system.
While auto-ignition and open sources of ignition may be readily obvious, a more subtle however nonetheless critical source of ignition to regulate on any industrial painting project involving flammable solvents involves the production of static electricity. Equipment related to the spray-painting operation, such as spray application tools and ventilation gear, can generate static electrical energy.
In addition to exterior sources of ignition, spontaneous ignition can occur when rags or wastes soaked with paint solvents are left in open containers. Spontaneous ignition occurs when the gradual era of heat from oxidation of organic chemical compounds corresponding to paint solvents is accelerated till the ignition temperature of the gas is reached.
This condition is reached when the material is packed loosely permitting a big floor space to be exposed, there is enough air circulating across the material for oxidation to happen, however the natural ventilation out there is insufficient to carry the heat away fast enough to prevent it from build up.
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