Managers of petrochemical, refining, energy, offshore, pulp and paper and other facilities with intensive hot processes and piping systems are regularly challenged with performing all the necessary coatings maintenance work solely during times of outages. Outages are required so that course of gear could be properly maintained and repaired together with cleaning of pipelines and vessels, upkeep and replacement of pumps, motors and valves, upkeep coating operations, and other work that may solely be completed when the operations are shut down.
When coatings work has to be carried out on areas where elevated temperatures are concerned, many think that the ability has to be shut down. This will not be the case.
A query 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, but there are safety and well being points that have to be considered”.
Dangers to personnel have to be managed regardless of when or where work is carried out.
Safety and health issues
There is a range of safety and well being hazards that must be thought of on each industrial maintenance portray venture, whether the coating material is being utilized to hot steel or not. Some of these embrace proper material handling and storage, fall safety, control of fire and explosion hazards, and exposure to noise, heavy metals, solvents and different well being dangers.
These risks must be properly evaluated and managed on each industrial upkeep portray challenge, no matter when or where the work is performed. While present on any job, when applying specialty coatings to hot surfaces, some safety and health points should obtain extra consideration.
Flammable and combustible liquids in plenty of coatings (solvents) can vaporize and form flammable mixtures within the air, especially when atomized during spray utility or heated. The degree of hazard is decided by the following:
The auto ignition temperature (AIT) of the coating materials is the only most important problem when making use of coatings to sizzling operating tools. AIT is defined (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 warmth supply or contact with a heated floor without 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 enough vapour is given off to form an ignitable combination with the air, near the floor of the liquid”. In other phrases, the flash point describes the temperature of the liquid that is high sufficient to generate sufficient vapour to create a flame if a source of ignition have been launched.
For vapours of flammable liquids, there is a minimal focus beneath which the spread of the flame does not happen when in touch with a supply of ignition. This is the Lower Flammable Limit (LFL). There is a most focus of vapour within 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 concentration of vapours can support combustion.
If security procedures are adopted, outages will not be required whereas upkeep is performed.
Implementing controls
Applying coatings to scorching surfaces increases the rate at which the solvents are pushed off. When applying solvent borne coatings to scorching surfaces it must be assumed that the focus of vapours in the air may exceed the LFL (at least for a brief time after application). As with coating application to ambient temperature metal, controls must be applied.
While the LFL is likely to be achieved over a shorter time frame during sizzling application of coatings than coatings work performed at ambient conditions, the ensuing fire hazard exists in each applications. That is, the fireplace hazard and related controls have to be considered for the appliance of any solvent-borne flammable coating system, regardless of the work environment. It should be recognized that the gas element of the fireplace tetrahedron shall be present in each ‘hot’ and ‘ambient’ environments and basic steps must be taken to attenuate pointless solvent vapours in the work area. In addition, as outlined later, attention should also be directed to eliminating the remaining element of the tetrahedron – the supply of ignition.
Controlling flammable vapours
The gas element of a fireplace can be decreased by implementing primary controls similar to handling and storing flammable liquids in approved, self-closing containers, keeping the number of flammable liquids containers within the work area and in storage areas to the minimal essential and inside allowable (regulatory) limits.
Alkaline detergents similar to tri-sodium phosphate may be substituted, followed by floor washing with contemporary water or steam cleansing and pH testing of the floor, 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 under the LFL. Combustible gasoline indicators have to be calibrated in accordance with the manufacturer’s recommendations and have to be accredited to be used in flammable atmospheres. Operators of the tools have to be educated in correct tools operation.
Readings must be taken in the general work area and the neighborhood of the operator and in areas the place there are potential sources of ignition. Typically, items are set to alarm at 10% of the LFL. If the alarm sounds, coatings application work should instantly stop till the focus of flammable vapours is managed. The purpose of setting the alarm beneath the LFL is to provide a security issue that results in management measures being implemented before there is an imminent danger of fireplace or explosion.
Monitoring of the combustible vapour focus shall be essential as the effectiveness of pure ventilation could additionally be variable. If control of flammable vapours requires mechanical air flow, an occupational security or well being skilled or engineer with expertise in industrial ventilation should be consulted.
At a minimum, mechanical ventilation methods ought to provide adequate capacity to manage flammable vapours to under 10% of the LFL by both exhaust air flow to take away contaminants from the work space or by dilution air flow through introduction of contemporary air to dilute contaminants. As with flamable gasoline indicators, ventilation gear should be accredited for safe use in flammable atmospheres. In addition, air flow equipment have to be grounded and bonded.
Additional ventilation, if wanted, should be continuous throughout coatings application as concentrations could improve as extra surfaces are coated during the course of a work shift, and particularly on sizzling surfaces where the rate of vaporization is greater.
Ventilation throughout coatings application should be continuous, especially when working on hot surfaces.
Sources of Ignition
When making use of coatings to hot surfaces, the first source of ignition that readily involves thoughts is the heat from the floor being painted. The AIT of the coating materials is the single most essential concern when applying coatings to scorching operating equipment. The AIT of a substance or combination is the minimum temperature at which a vapour-air mixture will ignite when in touch with a heated floor, without the presence of any open spark or flame.
The key to controlling this source of ignition is to confirm the surfaces being coated are under the AIT of the coatings being utilized. While floor temperatures may be known/available in plenty of services, all floor areas of the process/piping being painted and/or any gear adjacent to the items being painted the place overspray may deposit should be measured for precise floor temperature. pressure gauge 4 นิ้ว should be in comparability with the AIT of the coating system.
While auto-ignition and open sources of ignition may be readily obvious, a more subtle however nonetheless important source of ignition to regulate on any industrial painting venture involving flammable solvents entails the production of static electrical energy. Equipment related to the spray-painting operation, such as spray application gear and ventilation tools, 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 gradual technology of warmth from oxidation of natural chemical substances corresponding to paint solvents is accelerated until the ignition temperature of the gasoline is reached.
This situation is reached when the material is packed loosely permitting a big surface area to be exposed, there may be sufficient air circulating around the material for oxidation to happen, but the pure air flow out there is insufficient to carry the warmth away quick enough to forestall it from increase.
For more info, go to www.ppgpmc.com/Oil-Gas-Chemical.aspx
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