Invisible safety. The new PROTELACK SFP fire protection coating system
How to increase the fire resistance of steel while maintaining the aesthetics and shape of the structure? MERCOR introduces a new paint coating system PROTELACK SFP, which consists of an intumescent fire paint, as well as a primer, anti-corrosion paint and a topcoat paint, in any RAL color. Mateusz Chmurczyk, Product Manager from the Building Structure Protection Department at MERCOR, talks about the application, advantages and requirements of the system.
How does unprotected steel behave during a fire?
Mateusz Chmurczyk, Product Manager from the Building Structure Protection Department at MERCOR: Despite the fact that steel is a non-flammable material, unprotected steel starts to heat up rapidly due to thermal radiation. After just a few minutes, it loses its load-bearing capacity. The thicker the profile, the harder it is to heat up, which is why this element has a greater thermal capacity. The thinner the element, the lower the thermal capacity and the faster the heating. This is measured by the cross-section mass index, which is expressed by the proportion of the profile circumference to its cross-sectional area. The shapes of the profiles also have an impact on this. Closed profiles heat up and bend much faster than open profiles.
The second important factor that determines the selection of fire protection thickness is the critical temperature of the steel structural element. Expressed in degrees Celsius, it illustrates the temperature at which excessive deformations, e.g. deflections, will occur for a given profile. The purpose of fire protection coatings is to maintain the temperature in the protected profile lower than a specific critical temperature for a given time, e.g. 30 minutes for R 30.
So how long can unprotected steel withstand a fire?
MC: Very thick profiles, i.e. those that were used in the past for construction, can withstand up to 15 minutes without protection. Thinner profiles withstand only a few minutes. Contrary to appearances, an unprotected wooden beam will withstand longer than an unprotected steel beam. A wooden beam measuring 25 x 25 cm can withstand a fire for up to 2 hours!
The problem may not only be a complete lack of protection, because such a situation occurs relatively rarely, but also insufficient protection that does not cover the entire structure. Older structures were protected with various means, for example vermiculite spray, which unfortunately crumbled over time. Exposed areas are exposed to fire, so this practically means no fire protection. Ultimately, the resistance of the entire structure is as strong as its weakest link.
Designers are keen to choose paint protection. Why?
MC: If very high aesthetics are required, for example on facade structures. In such situations, paints are selected, similarly to historic buildings. Then, specific requirements imposed by the nature of the building define the final effect, and the cost is a secondary parameter.
Unfortunately, fire protection is often not included in the schedule or is described only in a very general provision that structures must be protected to class R 60 in a painting system. There are no specific guidelines and no system is selected. If this system is selected, it is sometimes a "shot in the dark", because it has proven itself in another location, which does not mean, however, that this system is optimal for a given case.
Painting protection has an additional advantage - negligible low weight compared to, for example, plate protection.
So if the designer at the design stage is not sure what to choose, or, for example, the contractor receives a project in which these parameters are not sufficiently defined, this is the time to contact MERCOR experts.
MC: Exactly. I would like to add that MERCOR experts also have experience in the application of fire protection, they can choose the best method and recommend a contractor.
What about cost issues?
MC: It is best to determine the costs together with the fire protection contractor, because a large part of the cost of performing fire protection painting is labor. A lot of additional protection is needed, primarily the surrounding surfaces, such as covering with foil or gluing covers so as not to dirty the elements surrounding the structure. The further the construction work is, the more expensive it is to perform these activities, because the scale of additional protection is greater.
MERCOR has just introduced a new type of fire protection to its offer – the PROTELACK SFP painting system, consisting of a fire-resistant intumescent paint, as well as an anti-corrosion primer and a topcoat with the option of choosing a colour from the full RAL palette. In what cases can this system be used?
MC: This system allows you to protect open profiles of steel structures up to class R 120, and closed profiles up to class R90. I would like to draw your attention to our PRIMELACK S paint, which is a primer and is suitable for less prepared surfaces, up to class St 2, which are surfaces prepared by manual cleaning. This is a very good solution for old structures, i.e. those on which there is some coating previously applied. In the case where it is not possible to sandblast it or it would be too expensive, the best option is manual preparation. Then the application of PRIMELACK S allows you to protect primarily against corrosion, and also provides an adhesive layer for the fire paint applied in the next step.
What else makes the PROTELACK system stand out?
MC: The competitive advantage of the PROTELACK SPF system is the possibility of faster application of individual layers due to their drying speed, which on the one hand speeds up the implementation of the stage, and at the same time makes the costs at a rational level. There is also a fast-drying version PROTELACK SFP Fast, which, depending on the temperature, dries from 50% to twice as fast as PROTELACK SFP. It stands out from single-component fire protection paints in terms of the drying speed of the layers and in a situation where cost savings are concerned, it is worth choosing this option, which will significantly speed up the time of implementation of fire protection. After drying, the PROTELACK SFP Fast coating has identical properties to PROTELACK SFP. The advantage of the PROTELACK SFP fire protection paint is also the possibility of its application on existing anti-corrosion coatings (epoxy and polyurethane) to a total thickness of 330 microns, provided that they are in good condition and degreased, cleaned and roughened before applying the PROTELACK SFP paint.
Is the aesthetics of the finish of such a coating also an advantage?
MC: Aesthetics are very important. We preserve the original shape of the steel elements. This is particularly important in the case of historic buildings. We are currently in the process of securing steel structures in the historic market hall in Gdańsk, where each element has its own specific ornaments that must preserve this shape. The PROTELACK SFP system is therefore an ideal choice. Additionally, we can choose the color and gloss of the topcoat. We offer the full RAL palette, which allows you to match the color to any interior, including historic ones. In indoor conditions, even with increased humidity, PROTELACK SFP paint can be applied without a topcoat. In such a situation, however, it is a white finish. This is very useful, for example, when finishing office interiors.
We assume that the steel structure has been properly secured. How does this system behave during a fire? What happens?
MC: During a fire, at a temperature of 150°C, the fire paint begins to swell. It breaks the polyurethane, topcoat layer and creates an appropriate cooling and insulating barrier for the structure. The topcoat should behave in this way, allowing the layer underneath to swell, i.e. not limiting its increase in volume during elevated temperatures in fire conditions. The thickness of the polyurethane topcoat layer, which allows for external application, in the case of the PROTELACK SFP system is only 120 microns.
The fire paint swells from about 40 to 60 times, i.e. for a dry layer of 1 millimetre, we obtain a layer of 4 to 6 cm during a fire.
When designing such a structure, it is necessary to provide space for the fire protection layer to swell - maintain an appropriate distance between the elements so that the system has a chance to work.
What are the different ways to apply the PROTELACK SFP system and which one is the best?
MC: The best method is the so-called airless spraying, where using a painting unit, in controlled conditions, we spray layers of fire protection paint. For the regular version of PROTELACK SFP, we can apply up to 1.5 millimeters of paint in a dry layer, which is about 2 mm of wet paint, i.e. a very thick layer. Most open profiles up to class R 60 can be protected in this way in one layer, i.e. during one application.
Is it possible to combine applications? For example, an anti-corrosion layer with a brush and a fire protection layer with a generator?
MC: It is possible, but it will prolong the implementation, which increases the costs, but such situations also happen. In one facility, where fire protection was done too late, the window joinery elements were already installed. Unfortunately, they were very close to the elements that were to be fire protected and there was a very high risk of dirtying the windows. In this situation, the application was done manually, using a brush and roller.
Thank you for the interview!
Interviewer: Izabela Adamska, Marketing Project Coordinator MERCOR.
