Managers of petrochemical, refining, power, offshore, pulp and paper and different facilities with intensive scorching processes and piping techniques are frequently challenged with performing all the required coatings maintenance work only during times of outages. Outages are required in order that process equipment may be properly maintained and repaired together with cleansing of pipelines and vessels, upkeep and substitute of pumps, motors and valves, upkeep coating operations, and other work that can solely be accomplished when the operations are shut down.
When coatings work needs to be carried out on areas where elevated temperatures are involved, many suppose that the ability must be shut down. This will not be the case.
ไดอะแฟรม ซีล posed by facility managers is, “Can I do maintenance painting work while the plant is operating?” As described below, the reply is, “Yes you presumably can, however there are security and health points that must be considered”.
Dangers to personnel must be managed regardless of when or the place work is carried out.
Safety and well being issues

There is a spread of safety and health hazards that must be thought-about on each industrial maintenance painting challenge, whether or not the coating materials is being utilized to hot metal or not. Some of these include correct materials dealing with and storage, fall safety, management of fireside and explosion hazards, and exposure to noise, heavy metals, solvents and other well being risks.
These dangers must be correctly evaluated and managed on every industrial upkeep portray venture, no matter when or the place the work is carried out. While present on any job, when making use of specialty coatings to scorching surfaces, some security and well being issues should obtain additional consideration.
Flammable and combustible liquids in plenty of coatings (solvents) can vaporize and kind flammable mixtures within the air, particularly when atomized throughout spray software or heated. The diploma of hazard depends on the following:
The auto ignition temperature (AIT) of the coating material is the only most necessary 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 own heat supply or contact with a heated floor with out the presence of an open spark or flame.”

diaphragm seal of flash point as outlined by NFPA 30 is “the minimum temperature of a liquid at which enough vapour is given off to type an ignitable mixture with the air, close to the surface of the liquid”. In different phrases, the flash point describes the temperature of the liquid that’s excessive 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 doesn’t occur when in contact with a supply of ignition. This is the Lower Flammable Limit (LFL). There is a maximum concentration 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 focus of vapours can help combustion.
If security procedures are adopted, outages will not be required while maintenance is carried out.
Implementing controls

Applying coatings to sizzling surfaces increases the rate at which the solvents are driven off. When making use of solvent borne coatings to sizzling surfaces it have to be assumed that the focus of vapours in the air might exceed the LFL (at least for a short time after application). As with coating application to ambient temperature metal, controls should be carried out.
While the LFL is likely to be achieved over a shorter time period during scorching utility of coatings than coatings work performed at ambient circumstances, the ensuing hearth hazard exists in both applications. That is, the fire hazard and related controls must be considered for the applying of any solvent-borne flammable coating system, regardless of the work setting. It have to be acknowledged that the gas element of the fireplace tetrahedron might be present in each ‘hot’ and ‘ambient’ environments and fundamental steps have to be taken to minimize unnecessary solvent vapours in the work area. In addition, as outlined later, attention should even be directed to eliminating the remaining component of the tetrahedron – the supply of ignition.
Controlling flammable vapours

The gasoline component of a fire can be reduced by implementing basic controls such as dealing with and storing flammable liquids in permitted, self-closing containers, maintaining the variety of flammable liquids containers within the work space and in storage areas to the minimal necessary and inside 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 concentration of flammable vapours is below the LFL. Combustible gas indicators have to be calibrated in accordance with the manufacturer’s recommendations and have to be approved to be used in flammable atmospheres. Operators of the tools should be educated in proper gear operation.
Readings must be taken within the common 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 software work ought to immediately cease until the focus of flammable vapours is controlled. The objective of setting the alarm beneath the LFL is to supply a safety factor that results in management measures being applied before there is an imminent danger of fire or explosion.
Monitoring of the flammable vapour focus shall be essential because the effectiveness of pure ventilation could additionally be variable. If management of flammable vapours requires mechanical air flow, an occupational security or health skilled or engineer with experience in industrial air flow should be consulted.
At a minimal, mechanical ventilation methods ought to provide enough capability to control flammable vapours to beneath 10% of the LFL by either exhaust air flow to take away contaminants from the work space or by dilution ventilation by way of introduction of recent air to dilute contaminants. As with เกจวัดแรงดัน , ventilation equipment have to be permitted for protected use in flammable atmospheres. In addition, air flow tools have to be grounded and bonded.
Additional ventilation, if needed, ought to be steady throughout coatings utility as concentrations may improve as more surfaces are coated in the course of the course of a piece shift, and particularly on scorching surfaces the place the rate of vaporization is greater.
Ventilation throughout coatings utility must be continuous, especially when working on scorching surfaces.
Sources of Ignition

When making use of coatings to hot surfaces, the first source of ignition that readily comes to thoughts is the heat from the surface being painted. The AIT of the coating material is the only most important issue when applying coatings to sizzling working tools. The AIT of a substance or mixture is the minimum 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 source of ignition is to confirm the surfaces being coated are below the AIT of the coatings being utilized. While surface temperatures could additionally be known/available in many services, all floor areas of the process/piping being painted and/or any tools adjacent to the gadgets being painted the place overspray may deposit must 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 may be readily apparent, a extra subtle but nonetheless crucial supply of ignition to manage on any industrial painting challenge involving flammable solvents entails the manufacturing of static electrical energy. Equipment related to the spray-painting operation, similar to spray application gear and air flow tools, can generate static electricity.
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 happens when the gradual era of heat from oxidation of natural chemicals corresponding to paint solvents is accelerated until the ignition temperature of the gas is reached.
This condition is reached when the material is packed loosely allowing a large surface space to be uncovered, there’s enough air circulating across the material for oxidation to happen, however the natural air flow obtainable is inadequate to hold the heat away fast sufficient to prevent it from building up.
For extra info, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx

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