Managers of petrochemical, refining, power, offshore, pulp and paper and other services with extensive sizzling processes and piping methods are regularly challenged with performing all the mandatory coatings upkeep work solely during periods of outages. Outages are required in order that course of tools can be correctly maintained and repaired together with cleansing of pipelines and vessels, maintenance and replacement of pumps, motors and valves, upkeep coating operations, and different work that can solely 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 ability must be shut down. This is probably not the case.
A question incessantly posed by facility managers is, “Can I do maintenance portray work whereas the plant is operating?” As described under, the answer is, “Yes you presumably can, however there are safety and well being issues that should be considered”.
Uncharted to personnel should be managed no matter when or the place work is carried out.
Safety and health issues
There is a variety of safety and well being hazards that have to be thought of on every industrial maintenance portray challenge, whether the coating material is being utilized to scorching steel or not. Some of these embrace proper material handling and storage, fall protection, management of fireplace and explosion hazards, and publicity to noise, heavy metals, solvents and different health risks.
These dangers have to be properly evaluated and controlled on each industrial maintenance portray challenge, regardless of when or the place the work is performed. While present on any job, when applying specialty coatings to scorching surfaces, some safety and health points should receive additional consideration.
Flammable and flamable liquids in many coatings (solvents) can vaporize and kind flammable mixtures in the air, especially when atomized throughout spray utility or heated. The degree of hazard is determined by the next:
The auto ignition temperature (AIT) of the coating materials is the single most essential issue when applying 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 minimal temperature at which a flammable gas-air or vapour-air mixture will ignite from its personal heat supply or contact with a heated surface without 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 form an ignitable combination with the air, near the surface of the liquid”. In other phrases, the flash level describes the temperature of the liquid that’s high sufficient to generate enough vapour to create a flame if a supply of ignition were launched.
For vapours of flammable liquids, there’s a minimal concentration below which the unfold of the flame doesn’t occur when in contact with a source of ignition. This is the Lower Flammable Limit (LFL). There is a most concentration of vapour within the air above which the unfold of the flame does not happen. This is the Upper Flammable Limit (UFL). The flammable vary is between the LFL and the UFL, when the focus of vapours can assist combustion.
If security procedures are adopted, outages is probably not required whereas upkeep is performed.
Implementing controls
Applying coatings to sizzling surfaces will increase the speed at which the solvents are driven off. When making use of solvent borne coatings to sizzling surfaces it have to be assumed that the concentration of vapours within the air could exceed the LFL (at least for a short while after application). As with coating utility to ambient temperature steel, controls should be carried out.
While the LFL is more doubtless to be achieved over a shorter period of time during hot utility of coatings than coatings work performed at ambient conditions, the ensuing hearth hazard exists in both applications. That is, the fireplace hazard and related controls must be thought-about for the applying of any solvent-borne flammable coating system, regardless of the work surroundings. It have to be recognized that the gasoline part of the hearth tetrahedron might be current in each ‘hot’ and ‘ambient’ environments and primary steps must be taken to attenuate pointless solvent vapours within the work area. In addition, as outlined later, consideration should even be directed to eliminating the remaining element of the tetrahedron – the supply of ignition.
Controlling flammable vapours
The fuel component of a hearth could be decreased by implementing basic controls similar to dealing with and storing flammable liquids in accredited, self-closing containers, keeping the variety of flammable liquids containers within the work space and in storage areas to the minimum needed and within allowable (regulatory) limits.
Alkaline detergents such as tri-sodium phosphate could also be substituted, followed by surface washing with contemporary water or steam cleansing and pH testing of the surface, or non-combustible solvents corresponding to 1,1,1 trichloroethane) for pre-surface preparation solvent cleaning.
Combustible fuel indicators must be used to confirm that the focus of flammable vapours is below the LFL. Combustible gasoline indicators have to be calibrated in accordance with the manufacturer’s suggestions and must be accredited for use in flammable atmospheres. Operators of the tools should be trained in proper tools operation.
Readings ought to be taken in the common work area 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 software work should instantly cease until the focus of flammable vapours is managed. The function of setting the alarm beneath the LFL is to offer a security issue that ends in management measures being implemented before there might be an imminent danger of fire or explosion.
Monitoring of the combustible vapour focus might be needed as the effectiveness of pure air flow may be variable. If control of flammable vapours requires mechanical ventilation, an occupational safety or health skilled or engineer with expertise in industrial ventilation must be consulted.
At a minimal, mechanical air flow methods ought to provide enough capability to regulate flammable vapours to below 10% of the LFL by either exhaust ventilation to remove contaminants from the work space or by dilution air flow via introduction of recent air to dilute contaminants. As with flamable gas indicators, air flow equipment should be permitted for safe use in flammable atmospheres. In addition, ventilation equipment have to be grounded and bonded.
Additional air flow, if wanted, should be steady throughout coatings application as concentrations may enhance as more surfaces are coated in the course of the course of a work shift, and particularly on scorching surfaces where the speed of vaporization is larger.
Ventilation throughout coatings software ought to be continuous, particularly when working on scorching surfaces.
Sources of Ignition
When applying coatings to scorching surfaces, the first source of ignition that readily involves mind is the warmth from the surface being painted. The AIT of the coating materials is the one most essential issue when applying coatings to sizzling working equipment. The AIT of a substance or mixture is the minimum temperature at which a vapour-air combination will ignite when involved 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 could additionally be known/available in lots of services, all surface areas of the process/piping being painted and/or any equipment adjoining to the gadgets being painted where overspray may deposit must be measured for actual surface temperature. The outcomes ought to be in comparability with the AIT of the coating system.
While In less than -ignition and open sources of ignition may be readily obvious, a more subtle however nonetheless critical source of ignition to manage on any industrial portray project involving flammable solvents entails the manufacturing of static electricity. Equipment related to the spray-painting operation, similar to spray software equipment and ventilation equipment, can generate static electricity.
In addition to exterior 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 era of warmth from oxidation of organic chemicals corresponding to paint solvents is accelerated until the ignition temperature of the gas is reached.
This situation is reached when the material is packed loosely allowing a large floor space to be exposed, there’s enough air circulating around the material for oxidation to happen, however the pure ventilation obtainable is inadequate to carry the heat away fast sufficient to prevent it from building up.
For extra data, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx
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