Managers of petrochemical, refining, energy, offshore, pulp and paper and different amenities with extensive sizzling processes and piping systems are frequently challenged with performing all the necessary coatings maintenance work solely in periods of outages. Outages are required so that process tools can be correctly maintained and repaired including cleaning of pipelines and vessels, maintenance and alternative of pumps, motors and valves, upkeep coating operations, and different work that may only be achieved when the operations are shut down.
When coatings work needs to be performed on areas where elevated temperatures are involved, many think that the power needs to be shut down. This may not be the case.
A query incessantly posed by facility managers is, “Can I do upkeep portray work while the plant is operating?” As described beneath, the answer is, “Yes you’ll be able to, but there are safety and health issues that should be considered”.
Dangers to personnel have to be managed regardless of when or the place work is performed.
Safety and health issues
There is a range of security and health hazards that should be considered on every industrial maintenance painting project, whether or not the coating material is being utilized to sizzling steel or not. Some of these embrace proper material handling and storage, fall safety, control of fireplace and explosion hazards, and publicity to noise, heavy metals, solvents and other health dangers.
These dangers must be correctly evaluated and managed on each industrial upkeep portray challenge, no matter 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 ought to obtain extra consideration.
Flammable and combustible liquids in plenty of coatings (solvents) can vaporize and type flammable mixtures within the air, particularly 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 only most important problem when applying coatings to hot operating equipment. AIT is defined (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 concept of flash level as outlined by NFPA 30 is “the minimum temperature of a liquid at which enough vapour is given off to kind an ignitable mixture with the air, close to the surface of the liquid”. In other phrases, the flash level describes the temperature of the liquid that is high sufficient to generate sufficient vapour to create a flame if a supply of ignition were introduced.
For vapours of flammable liquids, there’s a minimum focus below which the spread of the flame does not occur when in contact 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 occur. This is the Upper Flammable Limit (UFL). The flammable vary is between the LFL and the UFL, when the concentration of vapours can assist combustion.
If safety procedures are adopted, outages may not be required whereas maintenance is carried out.
Implementing controls
Applying coatings to scorching surfaces will increase the speed at which the solvents are pushed off. When making use of solvent borne coatings to hot 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 application to ambient temperature steel, controls must be applied.
While the LFL is prone to be achieved over a shorter time frame during hot software of coatings than coatings work carried out at ambient situations, the ensuing fireplace hazard exists in both purposes. That is, the fireplace hazard and related controls should be considered for the application of any solvent-borne flammable coating system, regardless of the work setting. It must be recognized that the fuel element of the fire tetrahedron shall be present in both ‘hot’ and ‘ambient’ environments and fundamental steps have to be taken to reduce pointless solvent vapours in the work space. In addition, as outlined later, consideration should even be directed to eliminating the remaining component of the tetrahedron – the source of ignition.
Controlling flammable vapours
The fuel factor of a hearth can be decreased by implementing fundamental controls such as handling and storing flammable liquids in permitted, self-closing containers, maintaining the number of flammable liquids containers within the work area and in storage areas to the minimal needed and within allowable (regulatory) limits.
Alkaline detergents similar to tri-sodium phosphate could additionally be substituted, adopted by surface washing with contemporary water or steam cleansing and pH testing of the surface, or non-combustible solvents similar to 1,1,1 trichloroethane) for pre-surface preparation solvent cleaning.
Combustible gasoline indicators must be used to verify that the focus of flammable vapours is beneath the LFL. Combustible gasoline indicators must be calibrated in accordance with the manufacturer’s suggestions and should be accredited to be used in flammable atmospheres. Operators of the equipment should be trained in correct gear operation.
Readings ought to be taken within the general work space and the neighborhood of the operator and in areas the place there are potential sources of ignition. Typically, units are set to alarm at 10% of the LFL. If the alarm sounds, coatings utility work ought to instantly cease until the focus of flammable vapours is controlled. The objective of setting the alarm below the LFL is to supply a security factor that leads to control measures being implemented before there is an imminent danger of fire or explosion.
Monitoring of the flammable vapour focus shall be necessary as the effectiveness of pure ventilation could also be variable. If control of flammable vapours requires mechanical ventilation, an occupational safety or well being skilled or engineer with expertise in industrial ventilation should be consulted.
At a minimum, mechanical ventilation methods ought to provide enough capacity to manage flammable vapours to beneath 10% of the LFL by both exhaust ventilation to take away contaminants from the work space or by dilution air flow by way of introduction of contemporary air to dilute contaminants. As with combustible gas indicators, ventilation equipment should be permitted for protected use in flammable atmospheres. In addition, ventilation equipment should be grounded and bonded.
Additional air flow, if wanted, should be steady during coatings application as concentrations may improve as extra surfaces are coated in the course of the course of a work shift, and especially on sizzling surfaces the place the speed of vaporization is greater.
Ventilation during coatings software must be steady, particularly when working on hot surfaces.
Sources of Ignition
When making use of coatings to scorching surfaces, the primary source of ignition that readily comes to 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 scorching working gear. differential pressure gauge ราคา of a substance or mixture is the minimum temperature at which a vapour-air combination will ignite when in touch with a heated floor, without 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 applied. While floor temperatures could additionally be known/available in plenty of facilities, all floor areas of the process/piping being painted and/or any tools adjoining to the gadgets being painted the place overspray might deposit ought to be measured for precise floor temperature. The outcomes ought to be in comparability with the AIT of the coating system.
While auto-ignition and open sources of ignition could additionally be readily obvious, a more refined however nonetheless critical supply of ignition to regulate on any industrial portray venture involving flammable solvents includes the manufacturing of static electrical energy. Equipment related to the spray-painting operation, such as spray utility gear and ventilation gear, can generate static electrical energy.
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 occurs when the sluggish generation of heat from oxidation of natural chemical compounds such as paint solvents is accelerated till the ignition temperature of the fuel is reached.
This condition is reached when the fabric is packed loosely allowing a big floor area to be exposed, there is sufficient air circulating around the materials for oxidation to happen, however the pure air flow obtainable is insufficient to carry the heat away quick sufficient to prevent it from increase.
For extra data, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx
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