Managers of petrochemical, refining, energy, offshore, pulp and paper and other services with in depth scorching processes and piping systems are regularly challenged with performing all the required coatings upkeep work solely in periods of outages. Outages are required so that process tools may be properly maintained and repaired together with cleaning of pipelines and vessels, upkeep and alternative of pumps, motors and valves, upkeep coating operations, and other work that can solely be accomplished when the operations are shut down.
When coatings work must be carried out on areas the place elevated temperatures are concerned, many suppose that the facility has to be shut down. This may not be the case.
A question frequently posed by facility managers is, “Can I do upkeep painting work while the plant is operating?” As described below, the reply is, “Yes you probably can, but there are safety and well being points that have to be considered”.
Dangers to personnel have to be managed no matter when or where work is performed.
Safety and well being considerations
There is a variety of security and health hazards that should be thought-about on every industrial upkeep portray project, whether or not the coating material is being utilized to scorching metal or not. Some of those embody correct material handling and storage, fall safety, control of fireside and explosion hazards, and exposure to noise, heavy metals, solvents and different well being risks.
เกจวัดน้ำยาแอร์refco must be properly evaluated and managed on every industrial upkeep portray project, regardless of when or the place the work is carried out. While present on any job, when applying specialty coatings to scorching surfaces, some safety and health issues should obtain further consideration.
Flammable and combustible liquids in many coatings (solvents) can vaporize and kind flammable mixtures in the air, especially when atomized throughout spray software or heated. The degree of hazard depends on the next:
The auto ignition temperature (AIT) of the coating materials is the only most important issue when making use of coatings to hot working tools. AIT is outlined (by the National Safety Council publication Accident Prevention Manual For Business and Industry: Engineering & Technology) as “…the minimum temperature at which a flammable gas-air or vapour-air combination will ignite from its own heat source or contact with a heated floor with out the presence of an open spark or flame.”
The idea of flash point as defined by NFPA 30 is “the minimal temperature of a liquid at which enough vapour is given off to kind an ignitable mixture with the air, close to the floor of the liquid”. In other words, the flash level describes the temperature of the liquid that is excessive enough to generate enough vapour to create a flame if a source of ignition had been launched.
For vapours of flammable liquids, there’s a minimum concentration under which the unfold of the flame does not occur when in contact with a source of ignition. This is the Lower Flammable Limit (LFL). There is a maximum focus of vapour within 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 support combustion.
If security procedures are adopted, outages will not be required whereas maintenance is carried out.
Implementing controls
Applying coatings to sizzling surfaces will increase the rate at which the solvents are driven off. When making use of solvent borne coatings to scorching surfaces it have to be assumed that the concentration of vapours in the air may exceed the LFL (at least for a short while after application). As with coating software to ambient temperature steel, controls should be applied.
While the LFL is more likely to be achieved over a shorter time frame throughout sizzling utility of coatings than coatings work carried out at ambient conditions, the ensuing hearth hazard exists in both applications. That is, the hearth hazard and related controls have to be considered for the application of any solvent-borne flammable coating system, whatever the work environment. It should be recognized that the gas component of the hearth tetrahedron shall be present in both ‘hot’ and ‘ambient’ environments and basic steps must be taken to minimize pointless solvent vapours in the work area. In addition, as outlined later, consideration should also be directed to eliminating the remaining component of the tetrahedron – the supply of ignition.
Controlling flammable vapours
The fuel component of a fire may be lowered by implementing fundamental controls such as dealing with and storing flammable liquids in permitted, self-closing containers, maintaining the number of flammable liquids containers in the work area and in storage areas to the minimum needed and within allowable (regulatory) limits.
Alkaline detergents corresponding to tri-sodium phosphate may be substituted, adopted by surface washing with contemporary water or steam cleansing and pH testing of the floor, or non-combustible solvents such as 1,1,1 trichloroethane) for pre-surface preparation solvent cleaning.
Combustible gasoline indicators must be used to confirm that the focus of flammable vapours is below the LFL. Combustible gasoline indicators should be calibrated in accordance with the manufacturer’s recommendations and should be approved for use in flammable atmospheres. Operators of the tools should be trained in proper gear operation.
Readings should be taken in the general work area and the neighborhood of the operator and in areas where there are potential sources of ignition. Typically, models are set to alarm at 10% of the LFL. If the alarm sounds, coatings utility work should instantly cease until the concentration of flammable vapours is managed. The objective of setting the alarm below the LFL is to supply a safety factor that results in control measures being implemented earlier than there could be an imminent hazard of fire or explosion.
Monitoring of the flammable vapour focus will be essential because the effectiveness of natural air flow could additionally be variable. If management of flammable vapours requires mechanical air flow, an occupational safety or health skilled or engineer with experience in industrial ventilation must be consulted.
At a minimum, mechanical air flow techniques should provide enough capacity to control flammable vapours to beneath 10% of the LFL by either exhaust air flow to remove contaminants from the work space or by dilution air flow through introduction of contemporary air to dilute contaminants. As with combustible gas indicators, ventilation tools should be permitted for secure use in flammable atmospheres. In addition, ventilation tools have to be grounded and bonded.
Additional air flow, if needed, must be steady throughout coatings software as concentrations might improve as more surfaces are coated in the course of the course of a piece shift, and particularly on hot surfaces the place the speed of vaporization is greater.
Ventilation throughout coatings utility must be steady, especially when working on scorching surfaces.
Sources of Ignition
When making use of coatings to sizzling surfaces, the primary supply of ignition that readily involves thoughts is the warmth from the surface being painted. The AIT of the coating material is the only most necessary problem when applying coatings to sizzling operating gear. The AIT of a substance or combination is the minimum temperature at which a vapour-air combination will ignite when in touch with a heated floor, with out the presence of any open spark or flame.
The key to controlling this supply of ignition is to confirm the surfaces being coated are beneath the AIT of the coatings being applied. While floor temperatures may be known/available in lots of facilities, all floor areas of the process/piping being painted and/or any tools adjacent to the gadgets being painted the place overspray might deposit ought to be measured for precise floor temperature. The results must be in comparison with the AIT of the coating system.
While auto-ignition and open sources of ignition could also be readily obvious, a extra delicate however nonetheless important source of ignition to regulate on any industrial portray venture involving flammable solvents entails the manufacturing of static electrical energy. Equipment associated with the spray-painting operation, such as spray software equipment and ventilation gear, can generate static electricity.
In addition to external sources of ignition, spontaneous ignition can happen when rags or wastes soaked with paint solvents are left in open containers. Spontaneous ignition happens when the sluggish generation of heat from oxidation of natural chemical substances such as paint solvents is accelerated till the ignition temperature of the gasoline is reached.
This situation is reached when the fabric is packed loosely permitting a large surface space to be uncovered, there’s enough air circulating across the material for oxidation to happen, but the natural air flow obtainable is inadequate to hold the warmth away fast enough to prevent it from build up.
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