Managers of petrochemical, refining, energy, offshore, pulp and paper and different services with in depth scorching processes and piping techniques are incessantly challenged with performing all the mandatory coatings upkeep work solely during times of outages. Outages are required so that process tools can be properly maintained and repaired together with cleaning of pipelines and vessels, maintenance and substitute of pumps, motors and valves, upkeep 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 involved, many assume that the facility needs to be shut down. This may not be the case.
A question frequently posed by facility managers is, “Can I do upkeep portray work whereas the plant is operating?” As described under, the reply is, “Yes you can, however there are security and well being issues that must be considered”.
Dangers to personnel should 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 must be thought-about on each industrial upkeep portray venture, whether the coating materials is being utilized to hot metal or not. Some of these embody correct material handling and storage, fall protection, management of fireplace and explosion hazards, and publicity to noise, heavy metals, solvents and different well being dangers.
These dangers should be properly evaluated and controlled on each industrial upkeep painting venture, no matter when or the place the work is carried out. While current on any job, when making use of specialty coatings to sizzling surfaces, some safety and well being issues should obtain additional consideration.
Flammable and flamable liquids in many coatings (solvents) can vaporize and form flammable mixtures within the air, especially when atomized during spray application or heated. The diploma of hazard depends on the next:
The auto ignition temperature (AIT) of the coating material is the one most essential concern when making use of 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 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 concept of flash level as defined by NFPA 30 is “the minimal temperature of a liquid at which adequate vapour is given off to form an ignitable combination with the air, near the surface of the liquid”. In different phrases, the flash level describes the temperature of the liquid that is high enough to generate enough vapour to create a flame if a supply of ignition had been launched.
For vapours of flammable liquids, there’s a minimum focus beneath 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 happen. This is the Upper Flammable Limit (UFL). The flammable range is between the LFL and the UFL, when the focus of vapours can assist combustion.
If safety procedures are followed, outages may not be required whereas maintenance is performed.
Implementing controls
Applying coatings to scorching surfaces will increase 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 quick while after application). As with coating utility to ambient temperature metal, controls must be applied.
While the LFL is prone to be achieved over a shorter period of time during hot utility of coatings than coatings work performed at ambient situations, the ensuing hearth hazard exists in each purposes. That is, the fireplace hazard and associated controls must be thought-about for the application of any solvent-borne flammable coating system, whatever the work environment. It should be recognized that the gas part of the fire tetrahedron will be current in each ‘hot’ and ‘ambient’ environments and basic steps should be taken to minimize unnecessary solvent vapours in the work area. In addition, as outlined later, consideration must also be directed to eliminating the remaining element of the tetrahedron – the supply of ignition.
Controlling flammable vapours
The gas factor of a fireplace can be reduced by implementing fundamental controls corresponding to dealing with and storing flammable liquids in accredited, self-closing containers, maintaining the number of flammable liquids containers within the work area and in storage areas to the minimal needed and inside allowable (regulatory) limits.
Alkaline detergents corresponding to tri-sodium phosphate could also be substituted, adopted by surface washing with recent 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 gas indicators ought to be used to verify that the focus of flammable vapours is under the LFL. Combustible gasoline indicators have to be calibrated in accordance with the manufacturer’s recommendations and should be approved to be used in flammable atmospheres. Operators of the equipment have to be trained in proper gear operation.
Readings should be taken in the general work space and the vicinity of the operator and in areas the place there are potential sources of ignition. Typically, เกวัดแรงดันน้ำ are set to alarm at 10% of the LFL. If the alarm sounds, coatings utility work should instantly cease until the concentration of flammable vapours is managed. The function of setting the alarm beneath the LFL is to provide a safety issue that ends in control measures being implemented earlier than there is an imminent hazard of fireside or explosion.
Monitoring of the flammable vapour focus shall be essential because the effectiveness of natural ventilation may be variable. If control of flammable vapours requires mechanical ventilation, an occupational security or well being professional or engineer with expertise in industrial ventilation must be consulted.
At a minimal, mechanical air flow techniques ought to provide adequate capability to regulate flammable vapours to under 10% of the LFL by either exhaust ventilation to take away contaminants from the work space or by dilution air flow through introduction of recent air to dilute contaminants. As with combustible gasoline indicators, ventilation equipment have to be approved for protected use in flammable atmospheres. In addition, air flow equipment must be grounded and bonded.
Additional ventilation, if needed, ought to be continuous throughout coatings software as concentrations might increase as extra surfaces are coated in the course of the course of a piece shift, and particularly on sizzling surfaces where the speed of vaporization is higher.
Ventilation during coatings software must be continuous, especially when working on sizzling surfaces.
Sources of Ignition
When applying coatings to scorching surfaces, the first source of ignition that readily comes to thoughts is the warmth from the surface being painted. The AIT of the coating material is the one most important concern when applying 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 beneath the AIT of the coatings being utilized. While floor temperatures could also be known/available in many services, all floor areas of the process/piping being painted and/or any gear adjoining to the objects being painted where overspray could deposit must be measured for precise surface temperature. The outcomes ought to be in comparison with the AIT of the coating system.
While auto-ignition and open sources of ignition could additionally be readily apparent, a more subtle but nonetheless critical source of ignition to manage on any industrial portray venture involving flammable solvents includes the production of static electricity. Equipment related to the spray-painting operation, such as spray utility equipment and air flow tools, can generate static electrical energy.
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 technology of warmth from oxidation of natural chemical substances such as paint solvents is accelerated until the ignition temperature of the gas is reached.
This condition is reached when the material is packed loosely permitting a large floor space to be exposed, there could be sufficient air circulating around the material for oxidation to occur, however the pure ventilation available is insufficient to hold the heat away fast enough to forestall it from build up.
For extra information, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx
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