Powder coating
What are the risks?The process of applying powder coating is a potential fire hazard. Therefore, a company installing or operating a line must ensure that the equipment meets local regulations and good practice guidelines.
Spray painting is widely performed
In workshops throughout the world, spray painting is performed on a range of products, from small, individual items to full car bodies and other large items, on continuous production lines. The paint can be in liquid form and can be either solvent or water based. Coating can also be applied through an electrostatic powder coating process, which has been popular in the metal manufacturing sector since it was first introduced in the 1960s.
Manufacturers can apply the powder coating efficiently, and the cured coating provides good corrosion protection while also being cosmetically attractive. Risk engineers at If see many varieties of paint-shop installations when visiting our clients, with paint being applied both manually and automatically by robots.
The hazards associated with paints and solvents are toxicity and flammability. Even though there might be a lower level of hazards associated with using powder coating compared to conventional solvent-based paints, the process of applying powder coating is a potential fire hazard. Therefore, a company installing or operating a line must ensure that the equipment meets local regulations and good practice guidelines.
The dust cloud
AVK Holding A/S is a family-owned company headquartered in Galten, Denmark, with subsidiaries manufacturing different types of valves used in water and wastewater distribution, fire protection water supply, industrial applications, and gas distribution. AVK operates throughout the world with factory footprints on most continents.
If P&C took over the property insurance for AVK some years ago. There are many different work processes at the AVK sites, including metalworking with surface treatment, such as electrostatic powder coating, epoxy coating, and enamelling of metal components. Before the coating process is carried out, the components are typically blast cleaned before being painted.
Many of the paint lines at AVK are electrostatic powder coating lines, where a fine dust is sprayed onto a grounded workpiece. The spray application system is complete with electrostatic charging of the powder coating to charge the particles and effect a high level of transfer to the grounded workpiece. During the coating process, the components are heat-treated in a pre- and post-cure oven, where operating temperatures are 190-200˚C.
One of the hazards involving powder coating is that a fine dust cloud can form an explosive atmosphere when mixed with air, and this can cause an explosion and fire under unfavourable conditions.
Important to handle the risk with respect
AVK is very much aware of the risks involved with the powder coating processes, and according to ATEX 137, workplace directive 99/92/EC, states the minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres. It is important to handle the risk with respect, even in small paint units, as powder coatings, being fine organic materials, can give rise to dust explosions and contact allergies.
The ATEX directive consists of two EU directives describing what equipment and work space are allowed in an environment with an explosive atmosphere.
The ATEX directive covers explosions from gases and also from solid dust, which, contrary to common belief, can lead to hazardous explosions. Hazards relating to explosion risks are: gas/vapour/mist and powder/dust. All equipment used in hazardous (zoned) areas must be ‘ATEX Compliant’ and must be suitable for the zone in which it is used.
A fine dust cloud can form an explosive atmosphere.
Identifying risks
AVK runs a strict routine to identify potential hazard zones and potential ignition sources, and to provide adequate ventilation and powder collection systems. Ignition sources can include all open flames and welding activity, hot surfaces, and mechanically generated impact sparks; for example, a hammer blow on a rusty steel surface compared to a hammer blow on a flintstone.
Electric sparks are also common ignition sources, for example, a bad electrical connection or faulty electrical equipment. It is also important to control the electrostatic discharge risk. Static electricity can be generated by air sliding over a wing, or a non-conductive liquid flowing through a filter screen, and so on, and there are many more potential ignition sources.
It is therefore important that a skilled professional is consulted when evaluating the hazard zones and the potential ignition risks. Earthing of equipment is a focus area when installing a paint unit or preventing the formation of static electricity, among other things.
The risks vary
The layout of the paint facility is also highly important, to ensure safe escape routes, good ventilation and extraction systems, and good access for emergency services in the event of fire.
When it comes to the ventilation and powder collection systems, it is important that the systems are designed to minimise the amount of overspray, and excess powder is removed by exhaust extraction and collected for re-use or disposal.
Enclosed filter membrane collectors and cyclone collectors should be provided with explosion relief unless the openings that are provided give sufficient protection. The collection unit should preferably be located outside in a safe place, with the minimum enclosure required for weather protection. If it is necessary for the dust collection unit to be sited indoors, it should be in a separate area away from the working area.
The potential risks involved with paint shops are many and they vary.
“The potential risks involved with paint shops are many, and they vary from site to site”, says Bo Johansen, Group Production & Supply Chain Director at AVK Holding A/S. “It is therefore important that a thorough risk assessment is carried out on a case-by-case basis. It is the local production and facility managers’ responsibility to, among other things, ensure the necessary ATEX assessments in this context”.
AVK also works with automatic fire detection and suppression systems to detect, extinguish, or control a potential fire in paint lines that are of vital importance for their business. This is something our engineers acknowledge as highly effective in limiting loss in the case of a fire.
Another focus area when visiting a plant is whether the surrounding construction material encapsulating the paint area is made of the right material. We sometimes see clients using steel sandwich panels with combustible foam insulation for this kind of construction, especially for noise and dust reduction purposes, which in our opinion is a bad choice. Non-combustible steel sandwich panels are preferable.
An AVK subsidiary with a production site in Spain planned to establish a new spray-painting cabinet with steel sandwich panels including PIR insulation, and in connection with a recent risk survey, an If engineer recommended that AVK should use non-combustible insulated steel sandwich panels instead. This led to alterations in the choice of material, to a non-combustible solution, without compromising the function of the design and without further costs to AVK.
Human elements are important
Bo Johansen at AVK also points out that human elements are of great importance and employees need special training when working with explosive atmospheres. Wearing high-quality protective clothing and equipment is also vital when called for. AVK is fully aware of the need for good housekeeping and runs a strict housekeeping and maintenance regime in connection with their paint shops.
The list of hazards and risks related to paint shops and powder coating is long and only briefly touched upon in this article. As Bo Johansen concludes, it is important that a risk assessment is carried out by qualified technical personnel on each individual production site, and in this context, If has been able to provide valuable additional input.
Risk engineers at If also emphasize that it is important to keep up with new knowledge and solutions that can help to avoid accidents and losses. Even if spray painting is a common practice and powder coating has been around since the 1960s, the equipment and surrounding protective applications are constantly evolving.