By Vanesa Restrepo
Safety in industrial facilities has become one of the elements that most concern entrepreneurs in Latin America, who increasingly invest more resources in the development of accident and emergency prevention systems, as well as in the protection and reinforcement of the structures in which companies operate. As a result, the market for intumescent paints has grown in the region, despite the lack of regulation in the matter.
Chile is currently the only country in the Latin American region with regulations in force regarding the protection and prevention of fires, through the use of intumescent paints. In other regions such as Colombia and Brazil, their employment has begun to become more widespread thanks to the expansion of large companies and the growth of industrial and commercial areas in cities.
How do they work?
The book Organic Industrial Chemistry written by María Cinta Vincent Vela, Silvia Álvarez Blanco and other authors, points out that "intumescence is the property shown by certain paintings to react to thermal stimuli, decomposing certain substances of their formulation, which in turn react with each other forming a large volume of a spongy product that constitutes a true thermal insulator between the heat source and the material on which the intumescent."
According to this statement, we have that an intumescent paint is a coating that is applied on the steel structures of buildings and whose main function is to delay the effect of flames in case of fire, giving time for the conflagration to be controlled before the building collapses.
According to Colombian engineer Quilyam Casallas, from the multinational Sika, intumescent paints work in high temperatures preventing the properties of the metal from being altered. "The porposit is to ensure that the structural elements of carbon steel do not reach 500º C, because after it is achieved, the mechanical properties begin to be lost."
The possibility of delaying the effect of fire makes it feasible that lives can be saved, while reducing the damage caused by the fire in the building, since the paint protects its basic structure.
Rodrigo Infante, Manager of the commercial technical unit of the Chilean company Pinturas Ceresita & Soquina, explains that "the heat generated during a fire heats the metal structure, but when it reaches more or less 500°C it begins to lose its mechanical properties, finally collapsing when it exceeds 700°C".
The action of an intumescent paint begins when the surface temperature rises to 250º C. At that moment the coating begins to swell, forming a foam with thermal insulation properties, the thickness of which is 100 times greater than that of the film.
Formulation
In the Latin American market you can find intumescent water-based and solvent-based paints, although the latter tend to disappear, given their high VOC content. It is important to clarify that the action capacity and fire resistance of both paints is similar, so the emission of pollutants into the environment becomes the most noticeable difference between one and the other.
The formulation of intumescent paints is made from two types of essential components. The first of them is responsible for emitting gases once it has come into contact with the flames, while the second type of components is "an agent capable of producing a sponge through these gases", according to the Spanish Jordi Calvo, a technician in paints and coatings, who also points out that "the components in general are pentaerythrite and ammonium polyphosphate which is a gas generator".
When the film is heated, it breaks down the ingredients and forms the "sponge" film, which can go from 3mm to 30 cm. When the temperature reaches 400º C, the carbonates and pigments are decomposed and later, when the critical point is reached (500º C), the resin and the other organic compounds are decomposed. "After 500º C there are only oxides in the form of a kind of cotton," says Calvo.
The work of current formulators focuses on the development of materials that allow swelling to occur quickly and on the optimization of current components, in order to increase fire resistance.
Application
The good performance of an intumescent paint is directly proportional to the adequate pre-treatment of the surface on which it is to be applied.
Quilyam Casallas recently participated in the process of applying intumescent coatings in the Bancolombia building, a superstructure that houses the main financial institution in that country. Casallas explains that in that case about 400 gallons of 15% paint were used, which were applied on a hot-rolled carbon steel surface.
"For that case, the steel was treated by sandblasting. We used a base coating and then the intumescent paint was applied, using a sprinkler system. Then enamels were used to obtain UV-resistant finishes."
This process reveals the steps to take into account, so as not to affect the performance of the coating.
First of all it is necessary, as in any type of paint, that an appropriate cleaning of the surface is done to ensure an adequate adhesion of the film. Subsequently, an anticorrosive treatment is required to guarantee durability in the metal, since the corrosion of the structure will generate a detachment of the film.
The finishes will depend on the location of the treated surface. In case it is outdoors, varnishes can be applied to protect from the action of rain and solar radiation. In case it is an internal area, other water-based paints can be applied to give color or a protective varnish and thus avoid premature wear of the film.
Casallas also explains that it is important to do an adequate monitoring of the paint film, with the fn of preventing detachments, wear or corrosion. However, he assures that, in general, the resistance and durability of this type of paints is quite good, as long as an adequate pretreatment and application is made.
The Chilean Rodrigo Infante agrees in this assessment and specifies that "the paint (intumescent) is white and consequently a finishing paint must be applied, which varies from an enamel in water to an industrial paint"
Application on non-metallic surfaces
So far we have talked about the application of intumescent paints on metal structures. As stated above, Chile is the only country with legislation in force in this regard.
In an aside of the document "Paints resistant to fire and heat", written by Infante, it is explained that "The Chilean standard Nch 935/1-Of.97, establishes the procedure to determine the fire resistance of intumescent paints only for metal structures, and not for others such as wood, where the fire resistance of them, is achieved with large squadrons, or by coating it with mineral products, such as plasterboard or fiber cement."
The document also reveals that there are fireproof varnishes and fire retardant paints, but that the General Ordinance of Urbanism and Construction does not give specifications regarding their use.
At this point it is relevant to clarify that there are differences between intumescent paints and flame retardant materials, as explained in the book Organic Industrial Chemistry, cited above. "By definition, all intumescent materials are flame retardant, but not all flame retardants are intumescent, since it must possess, in addition to low flammability, a sponging capacity, creating an asyleent foam that generates a thermal gradient between the flames and the protected material."
Intumescent paint market
Investment in intumescent protection becomes more important within industrial construction decisions in Latin America. And it is that more and more different sectors, especially private investors consider it important to protect and minimize losses in cases of sinistro.
This is one of the reasons that has led to the creation of new lines of intumescent paints within traditional manufacturers in each country. Chile is, without a doubt, the country that has the greatest advantage in this area, although other countries such as Argentina (where unfortunate accidents have already been registered that could be avoided with corrosion protection), Brazil, Colombia and Mexico
According to Rodrigo Infante, from Ceresita, the expansion of Chilean companies throughout Latin America, especially warehouses and department stores, has favored the arrival of intumescent coatings to other countries. "We have exported this type of product to Peru, where there is no obligation. We have done it because there are Chilean construction companies there and they want to do it like this."
The Achilles' heel in the matter continues to be the absence of legislation in this regard. However, the formulators and builders unionized have already made their voice heard asking for greater state support in the matter, because in addition to the benefits in the part of commercialization, the regulation will save many lives in extreme cases.
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