Managers of petrochemical, refining, energy, offshore, pulp and paper and different services with extensive scorching processes and piping systems are incessantly challenged with performing all the mandatory coatings upkeep work only during times of outages. Outages are required so that process tools can be properly maintained and repaired together with cleansing of pipelines and vessels, upkeep and substitute of pumps, motors and valves, maintenance coating operations, and other work that may only be accomplished when the operations are shut down.
When coatings work must be performed on areas where elevated temperatures are involved, many assume that the power has to be shut down. This is most likely not the case.
A question regularly posed by facility managers is, “Can I do maintenance painting work while the plant is operating?” As described below, the reply is, “Yes you’ll have the ability to, but there are security and well being points that have to be considered”.
Dangers to personnel should be managed regardless of when or the place work is performed.
Safety and well being considerations
There is a range of security and health hazards that have to be considered on every industrial upkeep portray challenge, whether the coating materials is being utilized to hot metal or not. Some of these embody correct material dealing with and storage, fall safety, management of fireplace and explosion hazards, and exposure to noise, heavy metals, solvents and different health risks.
These dangers should be correctly evaluated and managed on every industrial upkeep portray challenge, regardless of when or the place the work is performed. While present on any job, when applying specialty coatings to sizzling surfaces, some safety and well being points should receive further consideration.
Flammable and flamable liquids in many coatings (solvents) can vaporize and type flammable mixtures in the air, especially when atomized throughout 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 important 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 minimal temperature at which a flammable gas-air or vapour-air combination will ignite from its own warmth source or contact with a heated floor without the presence of an open spark or flame.”
The concept of flash point as outlined by NFPA 30 is “the minimal temperature of a liquid at which adequate vapour is given off to kind an ignitable mixture with the air, close to the floor of the liquid”. In other phrases, the flash point describes the temperature of the liquid that’s high enough to generate enough vapour to create a flame if a supply of ignition have been introduced.
For digital pressure gauge of flammable liquids, there’s a minimal concentration below which the spread of the flame does not happen when in contact with a source of ignition. This is the Lower Flammable Limit (LFL). There is a maximum focus of vapour within the air above which the spread 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 security procedures are adopted, outages is in all probability not required while upkeep is carried out.
Implementing controls
Applying coatings to sizzling surfaces will increase the rate at which the solvents are driven off. When applying solvent borne coatings to sizzling surfaces it have to be assumed that the concentration of vapours within the air may exceed the LFL (at least for a short while after application). As with pressure gauge octa to ambient temperature metal, controls should be applied.
While the LFL is likely to be achieved over a shorter period of time during sizzling utility of coatings than coatings work performed at ambient circumstances, the ensuing fire hazard exists in each applications. That is, the fireplace hazard and related controls should be thought of for the appliance of any solvent-borne flammable coating system, regardless of the work surroundings. It should be acknowledged that the gasoline component of the hearth tetrahedron will be present in each ‘hot’ and ‘ambient’ environments and fundamental steps should be taken to reduce pointless solvent vapours in the work area. In addition, as outlined later, consideration should even be directed to eliminating the remaining component of the tetrahedron – the source of ignition.
Controlling flammable vapours
The gas component of a fire may be decreased by implementing primary controls corresponding to handling and storing flammable liquids in permitted, self-closing containers, preserving the number of flammable liquids containers within the work space and in storage areas to the minimal needed and within allowable (regulatory) limits.
Alkaline detergents such as tri-sodium phosphate may be substituted, followed by floor washing with recent water or steam cleaning and pH testing of the floor, or non-combustible solvents such as 1,1,1 trichloroethane) for pre-surface preparation solvent cleansing.
Combustible gasoline indicators must be used to verify that the focus of flammable vapours is under the LFL. Combustible gasoline indicators must be calibrated in accordance with the manufacturer’s suggestions and should be approved to be used in flammable atmospheres. Operators of the equipment should be skilled in proper tools operation.
Readings ought to be taken in the common work area and the vicinity of the operator and in areas the place there are potential sources of ignition. Typically, models are set to alarm at 10% of the LFL. If the alarm sounds, coatings application work ought to immediately cease until the concentration of flammable vapours is controlled. The purpose of setting the alarm beneath the LFL is to supply a safety issue that results in management measures being applied before there may be an imminent hazard of fireplace or explosion.
Monitoring of the combustible vapour focus shall be essential because the effectiveness of natural air flow may be variable. If management of flammable vapours requires mechanical air flow, an occupational security or well being skilled or engineer with expertise in industrial air flow ought to be consulted.
At a minimal, mechanical ventilation techniques ought to provide enough capability to manage flammable vapours to under 10% of the LFL by both exhaust ventilation to take away contaminants from the work space or by dilution air flow via introduction of fresh air to dilute contaminants. As with flamable gasoline indicators, air flow tools must be accredited for safe use in flammable atmospheres. In addition, air flow gear have to be grounded and bonded.
Additional ventilation, if wanted, ought to be steady during coatings utility as concentrations could improve as more surfaces are coated in the course of the course of a work shift, and especially on scorching surfaces where the speed of vaporization is larger.
Ventilation throughout coatings utility should be continuous, particularly when working on hot surfaces.
Sources of Ignition
When applying coatings to hot surfaces, the first source of ignition that readily involves thoughts is the heat from the surface being painted. The AIT of the coating material is the single most essential problem when making use of coatings to hot operating equipment. The AIT of a substance or combination 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 supply of ignition is to verify the surfaces being coated are under the AIT of the coatings being utilized. While floor temperatures may be known/available in lots of facilities, all floor areas of the process/piping being painted and/or any tools adjacent to the gadgets being painted the place overspray may deposit should be measured for precise surface temperature. The results should be compared to the AIT of the coating system.
While auto-ignition and open sources of ignition could additionally be readily obvious, a extra delicate however nonetheless important supply of ignition to regulate on any industrial portray challenge involving flammable solvents includes the manufacturing of static electricity. Equipment related to the spray-painting operation, such as spray application tools and ventilation gear, 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 happens when the slow generation of warmth from oxidation of organic chemical substances similar to paint solvents is accelerated until the ignition temperature of the fuel is reached.
This situation is reached when the material is packed loosely allowing a big surface space to be uncovered, there is sufficient air circulating across the materials for oxidation to occur, but the natural air flow available is insufficient to carry the warmth away fast sufficient to forestall it from increase.
For more data, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx
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