เกจวัดแรงกด of petrochemical, refining, power, offshore, pulp and paper and other services with intensive sizzling processes and piping methods are frequently challenged with performing all the necessary coatings maintenance work only during times of outages. Outages are required in order that course of gear may be correctly maintained and repaired including cleansing of pipelines and vessels, upkeep and alternative of pumps, motors and valves, maintenance coating operations, and other work that may solely be achieved when the operations are shut down.
When coatings work needs to be carried out on areas the place elevated temperatures are concerned, many think that the power needs to be shut down. This is most likely not the case.
A query incessantly posed by facility managers is, “Can I do upkeep portray work while the plant is operating?” As described below, the answer is, “Yes you’ll have the ability to, but there are safety and health points that must be considered”.
Dangers to personnel should be managed regardless of when or where work is performed.
Safety and well being concerns
There is a spread of safety and well being hazards that should be thought-about on every industrial upkeep portray project, whether or not the coating material is being utilized to hot metal or not. Some of these embody proper material handling and storage, fall safety, management of fire and explosion hazards, and publicity to noise, heavy metals, solvents and different well being risks.
These risks have to be properly evaluated and controlled on every industrial upkeep painting project, regardless of when or the place the work is performed. While current on any job, when applying specialty coatings to hot surfaces, some security and well being points should receive extra consideration.
Flammable and flamable liquids in many coatings (solvents) can vaporize and type flammable mixtures within the air, particularly when atomized during spray software or heated. The degree of hazard is decided by the next:
The auto ignition temperature (AIT) of the coating material is the single most essential problem when making use of coatings to scorching operating gear. 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 mixture will ignite from its personal warmth supply or contact with a heated floor with out the presence of an open spark or flame.”
The idea of flash point as outlined by NFPA 30 is “the minimum temperature of a liquid at which adequate vapour is given off to form an ignitable mixture with the air, close to the floor of the liquid”. In other words, the flash point describes the temperature of the liquid that is excessive enough to generate enough vapour to create a flame if a supply of ignition were introduced.
For vapours of flammable liquids, there’s a minimum focus beneath which the unfold of the flame does not happen when in contact with a supply of ignition. This is the Lower Flammable Limit (LFL). There is a maximum concentration of vapour within the air above which the unfold of the flame does not occur. 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 safety procedures are followed, outages is in all probability not required whereas upkeep is performed.
Implementing controls
Applying coatings to sizzling surfaces increases the speed at which the solvents are pushed off. When applying solvent borne coatings to scorching surfaces it should be assumed that the concentration of vapours in the air may exceed the LFL (at least for a short time after application). As with coating utility to ambient temperature steel, controls have to be applied.
While the LFL is prone to be achieved over a shorter time period throughout hot utility of coatings than coatings work carried out at ambient conditions, the resulting fire hazard exists in each purposes. That is, the hearth hazard and related controls have to be thought of for the appliance of any solvent-borne flammable coating system, whatever the work surroundings. It have to be recognized that the fuel part of the fireplace tetrahedron shall be present in each ‘hot’ and ‘ambient’ environments and primary steps have to be taken to attenuate unnecessary solvent vapours in the work space. In addition, as outlined later, consideration should also be directed to eliminating the remaining element of the tetrahedron – the supply of ignition.
Controlling flammable vapours
The gas component of a hearth could be reduced by implementing fundamental controls such as dealing with and storing flammable liquids in approved, self-closing containers, keeping the number of flammable liquids containers within the work space and in storage areas to the minimum necessary and inside allowable (regulatory) limits.
Alkaline detergents similar to tri-sodium phosphate may be substituted, adopted by surface washing with fresh water or steam cleaning and pH testing of the surface, or non-combustible solvents such as 1,1,1 trichloroethane) for pre-surface preparation solvent cleansing.
Combustible fuel indicators ought to be used to verify that the focus of flammable vapours is below the LFL. Combustible gas indicators should be calibrated in accordance with the manufacturer’s suggestions and must be approved to be used in flammable atmospheres. Operators of the gear should be skilled in correct tools operation.
Readings should be taken within the common work area and the neighborhood of the operator and in areas where there are potential sources of ignition. Typically, items are set to alarm at 10% of the LFL. If the alarm sounds, coatings software work should immediately stop till 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 before there’s an imminent danger of fire or explosion.
Monitoring of the flammable vapour concentration might be needed because the effectiveness of natural air flow 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 methods ought to present adequate capacity to manage flammable vapours to below 10% of the LFL by both exhaust ventilation to take away contaminants from the work area or by dilution air flow via introduction of recent air to dilute contaminants. As with flamable fuel indicators, air flow gear have to be accredited for safe use in flammable atmospheres. In addition, air flow equipment must be grounded and bonded.
Additional ventilation, if wanted, ought to be continuous during coatings software as concentrations may enhance as extra surfaces are coated in the course of the course of a piece shift, and especially on hot surfaces the place the rate of vaporization is higher.
Ventilation throughout coatings utility ought to be steady, especially when working on sizzling surfaces.
Sources of Ignition
When applying coatings to hot surfaces, the first source of ignition that readily comes to thoughts is the heat from the floor being painted. The AIT of the coating materials is the single most important problem when making use of coatings to hot working tools. The AIT of a substance or combination is the minimal 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 verify the surfaces being coated are under the AIT of the coatings being utilized. While surface temperatures may be known/available in many facilities, all floor areas of the process/piping being painted and/or any gear adjacent to the gadgets being painted the place overspray could deposit ought to be measured for actual surface temperature. The results must be in comparability with the AIT of the coating system.
While auto-ignition and open sources of ignition could additionally be readily apparent, a extra delicate but nonetheless critical supply of ignition to regulate on any industrial painting project involving flammable solvents includes the manufacturing of static electricity. Equipment associated with the spray-painting operation, such as spray application tools and air flow equipment, 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 slow technology of warmth from oxidation of organic chemical substances similar to paint solvents is accelerated till the ignition temperature of the gas is reached.
This situation is reached when the material is packed loosely allowing a big floor space to be uncovered, there is sufficient air circulating across the material for oxidation to occur, however the natural air flow available is inadequate to carry the warmth away quick enough to stop it from increase.
For extra data, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx
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