Managers of petrochemical, refining, energy, offshore, pulp and paper and other services with extensive hot processes and piping techniques are frequently challenged with performing all the mandatory coatings upkeep work solely during periods of outages. Outages are required so that process tools could be properly maintained and repaired together with cleaning of pipelines and vessels, upkeep and replacement 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 has to be performed on areas the place elevated temperatures are concerned, many assume that the ability has to be shut down. This is most likely not the case.
A query regularly posed by facility managers is, “Can I do upkeep portray work whereas the plant is operating?” As described under, the reply is, “Yes you’ll be able to, but there are security and health points that have to be considered”.
Dangers to personnel have to be managed regardless of when or the place work is carried out.
Safety and well being considerations
There is a range of safety and well being hazards that have to be considered on each industrial upkeep painting project, whether the coating material is being utilized to sizzling steel or not. Some of these embody proper materials dealing with and storage, fall safety, control of fire and explosion hazards, and exposure to noise, heavy metals, solvents and other well being risks.
These dangers must be properly evaluated and managed 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 scorching surfaces, some safety and well being issues should obtain further consideration.
Flammable and combustible liquids in many coatings (solvents) can vaporize and kind flammable mixtures within the air, especially when atomized during spray utility or heated. The degree of hazard is determined by the following:
The auto ignition temperature (AIT) of the coating materials is the only most necessary issue when making use of coatings to sizzling operating 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 mixture will ignite from its personal warmth source 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 sufficient vapour is given off to form an ignitable combination with the air, near the surface of the liquid”. In other phrases, the flash point describes the temperature of the liquid that is high enough to generate enough vapour to create a flame if a supply of ignition were launched.
For vapours of flammable liquids, there’s a minimal focus beneath which the spread of the flame doesn’t occur when in touch with a source 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 range is between the LFL and the UFL, when the concentration of vapours can support combustion.
If security procedures are adopted, outages is probably not required whereas maintenance is carried out.
Implementing controls
Applying coatings to hot surfaces will increase the rate at which the solvents are pushed off. When making use of solvent borne coatings to scorching surfaces it should be assumed that the focus of vapours in the air could exceed the LFL (at least for a quick while after application). As with coating software to ambient temperature metal, controls must be applied.
While the LFL is likely to be achieved over a shorter period of time during scorching application of coatings than coatings work carried out at ambient conditions, the resulting fire hazard exists in both functions. That is, the hearth hazard and associated controls should be thought-about for the application of any solvent-borne flammable coating system, regardless of the work surroundings. It must be recognized that the gasoline part of the hearth tetrahedron shall be present in each ‘hot’ and ‘ambient’ environments and basic steps should be taken to minimize unnecessary solvent vapours within the work area. In addition, as outlined later, consideration should even be directed to eliminating the remaining factor of the tetrahedron – the supply of ignition.
Controlling flammable vapours
The gas factor of a fire could be decreased by implementing fundamental controls similar to handling and storing flammable liquids in approved, self-closing containers, preserving the variety of flammable liquids containers in the work space and in storage areas to the minimum essential and within allowable (regulatory) limits.
Alkaline detergents corresponding to tri-sodium phosphate could also be substituted, followed by surface washing with recent water or steam cleaning and pH testing of the surface, or non-combustible solvents similar to 1,1,1 trichloroethane) for pre-surface preparation solvent cleaning.
Combustible fuel indicators must be used to verify that the focus of flammable vapours is beneath the LFL. Combustible gasoline indicators should be calibrated in accordance with the manufacturer’s suggestions and have to be approved for use in flammable atmospheres. เกจวัดแรงดัน250bar of the equipment must be educated in correct equipment operation.
Readings should be taken in the general work area and the vicinity 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 cease until the focus of flammable vapours is controlled. The purpose of setting the alarm beneath the LFL is to provide a security factor that results in management measures being implemented before there could be an imminent danger of fireplace or explosion.
Monitoring of the flammable vapour concentration shall be necessary because the effectiveness of natural air flow could also be variable. If control of flammable vapours requires mechanical air flow, an occupational safety or well being skilled or engineer with experience in industrial air flow ought to be consulted.
At a minimum, mechanical ventilation methods should present adequate capability to regulate flammable vapours to below 10% of the LFL by both exhaust air flow to take away contaminants from the work area or by dilution air flow via introduction of contemporary air to dilute contaminants. As with combustible fuel indicators, air flow equipment have to be approved for secure use in flammable atmospheres. In addition, air flow equipment should be grounded and bonded.
Additional ventilation, if wanted, should be continuous during coatings utility as concentrations might enhance as extra surfaces are coated through the course of a work shift, and particularly on scorching surfaces the place the rate of vaporization is higher.
Ventilation throughout coatings utility should be continuous, particularly when working on scorching surfaces.
Sources of Ignition
When making use of coatings to sizzling surfaces, the first source of ignition that readily comes to mind is the warmth from the surface being painted. The AIT of the coating materials is the one most important issue when making use of coatings to sizzling operating tools. The AIT of a substance or combination is the minimum temperature at which a vapour-air mixture 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 under the AIT of the coatings being applied. While surface temperatures could also be known/available in lots of amenities, all floor areas of the process/piping being painted and/or any equipment adjacent to the gadgets being painted the place overspray might deposit must be measured for actual surface temperature. The results ought to be in comparability with the AIT of the coating system.
While auto-ignition and open sources of ignition may be readily obvious, a extra delicate but nonetheless crucial source of ignition to manage on any industrial painting challenge involving flammable solvents involves the manufacturing of static electricity. Equipment related to the spray-painting operation, similar to spray utility tools and ventilation 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 sluggish technology of heat from oxidation of organic chemical compounds 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 big surface space to be exposed, there’s enough air circulating across the material for oxidation to happen, however the natural ventilation available is insufficient to hold the warmth away fast enough to prevent it from building up.
For more info, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx
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