23 Jul From thin coats to big protection

Don’t let fire steal your building’s strength. Brett Shinn, Fire Testing Manager, Thomas Bell-Wright International Consultants, uncovers the power of intumescent coatings and how vital  achieving the necessary thickness of these coatings is.

Imagine a fire erupting in a building, but the heat barely penetrates or affects the building’s supporting structural steel beams and columns. One way this firefighting feat is achieved is by protective intumescent coatings applied to the steel, and these innovative paints are the secret weapon in passive fire protection designed to shield steel, wood and other materials when flames come knocking.

Intumescent coatings, in concept, work quite simply: upon exposure to heat, the paint undergoes a dramatic transformation and expands into a thick, insulating char. This char acts as a barrier, significantly delaying the time it takes for the fire to weaken the structure, allowing occupants precious time to evacuate and giving firefighters a fighting chance to extinguish the blaze before any substantial loss of structure or property.

The coatings, quite impressively, can be applied to structural steel members as thin as 1mm, and as thick as required, depending on what may be understood as the thermal mass of the member, and a required thickness is determined through fire-testing.

Understandably, however, this relationship between applied thickness and section factor must be well understood during the design, testing, specification and end-use phases.

Insulation for buildings

Going back to our original building fire, let’s consider a building made primarily of steel beams and columns which are protected with intumescent coatings. These members need protection which is a thickness of intumescent paint applied as a function of the section factor of the member. A section factor is, effectively, the thermal mass of a material and is the ratio of exposed area to the volume of the structural member. A lower section factor means there’s more volume and less surface area (i.e. a big, beefy section), so it’s harder to heat up and requires less protection. A high section factor means less volume and more surface area (i.e. a skinny section) and needs more protection.

Section factors and applied thicknesses may, however, be difficult to visualise. If we consider, for example, a jacket manufacturer for people instead of a paint manufacturer for steel, a considerate jacket maker would need to produce thick, insulated jackets for small people (i.e. people with high section factors) and rather thin jackets for stocky or larger people (i.e. people with low section factors). That is to say, a higher section factor means higher risk and higher protection.

Finding the right fit

Unfortunately, there’s no universal guide for paint thickness; most test data and information are R&D-based, and tightly held by companies as trade secrets. This, of course, presents a challenge but, fortunately, there are test standards and guides for how to actually test paint thickness to arrive at an optimal relationship between applied thickness and section factor. Additionally, while test information may not be publicly available, industry certification directories provide publicly available design tables which specify a manufacturer’s required thickness for a given section factor, but for their product – and this information can be incredibly useful as reference material when starting your own intumescent testing process.

To explain testing, if we return to our original premise of paint thickness for a given section factor, we must obviously establish that relationship through testing – just as any other manufacturers have. This is, at its core, establishing a minimum and maximum section factor range and a minimum and maximum applied thickness range which one may ever sell in the market, then testing those ranges over a matrix to cover everything in between. It sounds complex, but your local certification body and testing house can point you in the right direction. In a way, it’s really the same as the jacket manufacturer trying out their jacket thicknesses on various sizes of people to see what works for each combination.

Help at hand

Intumescent coatings offer a valuable tool in passive fire protection. By understanding the relationship between section factor and applied thickness, you can ensure these innovative paints provide the necessary protection for your building’s steelwork.

While navigating test data and industry certifications can seem complex, local certification bodies and testing houses can be invaluable partners in guiding you towards the optimal coating solution for your specific project. By working with qualified professionals and following established practices, you can ensure the right level of protection for your building. Remember, a little planning goes a long way in ensuring your building’s structural integrity during a fire, giving occupants precious time to evacuate and firefighters the opportunity to extinguish the blaze.

The future of coatings

Intumescent coatings are a testament to fire protection’s constant evolution. These innovative paints offer a lightweight, yet highly effective solution for safeguarding a building’s structural integrity during a fire. By understanding the crucial relationship between a structural member’s section factor and the applied thickness of the coating, you can ensure your building’s steelwork receives the necessary protection.

Looking ahead, the future of intumescent coatings is brimming with promise. Research and development in this field are constantly pushing the boundaries of performance and efficiency. We can expect to see even thinner yet more effective coatings emerge, alongside advancements in application methods and environmental sustainability.

Ultimately, by embracing innovative solutions like intumescent coatings, we can create safer and more fire-resistant buildings. This translates to peace of mind for occupants, precious time for evacuation during emergencies, and a fighting chance for firefighters to extinguish blazes before significant structural damage occurs. As fire safety technology continues to evolve, intumescent coatings remain a cornerstone of passive fire protection, offering a crucial line of defence against the devastating effects of fire.

There is certainly a lot to unpackage about intumescent, or other, structural member protection – be it from the point of a protection manufacturer entering the market, someone specifying or purchasing what’s specified for a project, or a testing and certification body working on a test plan – and it can be quite difficult to find someone to clearly explain all the nuances.