Managers of petrochemical, refining, power, offshore, pulp and paper and other services with in depth scorching processes and piping techniques are frequently challenged with performing all the required coatings maintenance work only in periods of outages. Outages are required so that process equipment could be properly maintained and repaired together with cleansing of pipelines and vessels, maintenance and substitute of pumps, motors and valves, maintenance coating operations, and different work that may only be completed when the operations are shut down.
When coatings work needs to be carried out on areas where elevated temperatures are involved, many think that the power must be shut down. This will not be the case.
A query frequently posed by facility managers is, “Can I do upkeep painting work while the plant is operating?” As described beneath, the answer is, “Yes you can, however there are security and well being points that should be considered”.
Dangers to personnel must be managed regardless of when or where work is carried out.
Safety and health issues
There is a variety of security and well being hazards that must be thought-about on each industrial upkeep painting project, whether the coating material is being utilized to scorching metal or not. Some of those include correct material dealing with and storage, fall safety, control of fireplace and explosion hazards, and exposure to noise, heavy metals, solvents and other health risks.
These dangers must be correctly evaluated and managed on each industrial maintenance portray project, no matter when or the place the work is performed. While current on any job, when making use of specialty coatings to sizzling surfaces, some security and well being issues ought to receive extra consideration.
Flammable and flamable liquids in lots of coatings (solvents) can vaporize and type flammable mixtures in the air, especially when atomized during spray software or heated. The diploma of hazard is dependent upon the following:
The auto ignition temperature (AIT) of the coating material is the one most necessary problem when applying coatings to sizzling operating gear. 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 combination will ignite from its own heat supply or contact with a heated floor with out the presence of an open spark or flame.”
The idea of flash level as outlined by NFPA 30 is “the minimum 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 point describes the temperature of the liquid that is high sufficient to generate enough vapour to create a flame if a source of ignition have been launched.
For vapours of flammable liquids, there’s a minimal concentration below which the unfold of the flame does not occur when involved 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 occur. This is the Upper Flammable Limit (UFL). The flammable range is between the LFL and the UFL, when the focus of vapours can support combustion.
If safety procedures are followed, outages may not be required while maintenance is performed.
Implementing controls
Applying coatings to hot surfaces increases the rate at which the solvents are pushed off. When applying solvent borne coatings to sizzling surfaces it should be assumed that the focus of vapours in the air may exceed the LFL (at least for a quick while after application). As with coating software to ambient temperature steel, controls must be implemented.
While the LFL is prone to be achieved over a shorter time frame during sizzling software of coatings than coatings work performed at ambient circumstances, the ensuing hearth hazard exists in each applications. That is, the fireplace hazard and related controls have to be thought-about for the applying of any solvent-borne flammable coating system, regardless of the work environment. It have to be acknowledged that the fuel component of the hearth tetrahedron will be present in both ‘hot’ and ‘ambient’ environments and basic steps have to be taken to minimize unnecessary solvent vapours within the work space. In addition, as outlined later, attention must even be directed to eliminating the remaining factor of the tetrahedron – the supply of ignition.
Controlling flammable vapours
The gas element of a fire can be decreased by implementing fundamental controls corresponding to dealing with and storing flammable liquids in approved, self-closing containers, maintaining the number of flammable liquids containers within the work space and in storage areas to the minimal needed and within allowable (regulatory) limits.
Alkaline detergents such as tri-sodium phosphate could also be substituted, adopted by surface washing with recent water or steam cleaning and pH testing of the floor, or non-combustible solvents corresponding to 1,1,1 trichloroethane) for pre-surface preparation solvent cleaning.
Combustible fuel indicators should be used to verify that the focus of flammable vapours is under the LFL. Combustible gas indicators must be calibrated in accordance with the manufacturer’s recommendations and must be accredited to be used in flammable atmospheres. Operators of the gear must be skilled in correct tools operation.
Readings should be taken in the common work space 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 immediately stop until the concentration of flammable vapours is controlled. เกจวัดแรงดันน้ำราคา of setting the alarm under the LFL is to offer a security factor that leads to management measures being implemented earlier than there’s an imminent hazard of fire or explosion.
Monitoring of the flammable vapour focus will be needed because the effectiveness of pure ventilation may be variable. If control of flammable vapours requires mechanical air flow, an occupational safety or health skilled or engineer with expertise in industrial air flow ought to be consulted.
At a minimum, mechanical ventilation techniques should present adequate capacity to control flammable vapours to beneath 10% of the LFL by both exhaust air flow to take away contaminants from the work space or by dilution air flow via introduction of fresh air to dilute contaminants. As with combustible gasoline indicators, air flow equipment have to be accredited for secure use in flammable atmospheres. In addition, ventilation tools have to be grounded and bonded.
Additional ventilation, if needed, ought to be steady throughout coatings software as concentrations may enhance as extra surfaces are coated during the course of a work shift, and particularly on hot surfaces the place the rate of vaporization is higher.
Ventilation throughout coatings application ought to be continuous, especially when working on sizzling surfaces.
Sources of Ignition
When applying coatings to sizzling surfaces, the first source of ignition that readily comes to thoughts is the warmth from the floor being painted. The AIT of the coating materials is the single most essential problem when applying coatings to sizzling working tools. The AIT of a substance or mixture is the minimal temperature at which a vapour-air combination will ignite when involved with a heated surface, 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 surface temperatures could additionally be known/available in many services, all floor areas of the process/piping being painted and/or any tools adjoining to the gadgets being painted where overspray might deposit must be measured for precise floor temperature. The results ought to be compared to the AIT of the coating system.
While auto-ignition and open sources of ignition could also be readily apparent, a extra refined however nonetheless crucial source of ignition to regulate on any industrial painting venture involving flammable solvents includes the production of static electricity. Equipment related to the spray-painting operation, similar to spray software equipment and air flow tools, can generate static electricity.
In addition to external sources of ignition, spontaneous ignition can occur when rags or wastes soaked with paint solvents are left in open containers. Spontaneous ignition happens when the slow era of warmth from oxidation of natural chemicals 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 area to be uncovered, there’s sufficient air circulating around the material for oxidation to occur, but the pure air flow available is inadequate to carry the heat away fast sufficient to forestall it from building up.
For extra info, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx
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