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Considerations for selection of the right coating for the Fire Protection of Steel

Sep 29, 2020

As would come as no surprise, steel is still the world's most significant designing, engineering, and construction material. It is utilised in numerous aspects of our lives — with construction heavily dependent on it for majority of buildings and structures (not to say anything about other industries – which are not our forte).
Though it can be protected from fire by encasement in masonry, concrete, or plasterboard, it is important to remember that eventually, it will soften at high temperatures, which can spell disaster for those buildings which are not protected.

It is because of this that years ago it became popular, then a requirement to apply fire proofing materials to the steel to help it maintain its strength for as long as possible. Fast forward to today and the building and engineering sector have increasingly embraced the use of intumescent coatings. They incorporate flame-retardant substances in fireproofing steel members in order to achieve industry efficacy ratings.
When intumescent substances are exposed to heat, their size increases in volume and their density decreases. Regularly utilised in passive fire protection of steel structures, intumescent coatings are ordinarily water-based, solvent-based, or epoxy-based paint-like materials and can be applied in structures where cellulosic fires (eg office buildings) or hydrocarbon (fuel refineries) may occur. In the event of fire, the material characteristically expands and forms a protective ‘char’ on steel which acts as a thermal insulator and works to delay the spread of fire given it doesn’t burn.

Although there are numerous factors that are used to determine the right selection for different uses, our primary focus of this piece is four (4) main areas that the specifier, engineer, or building owner need to consider – both to achieve their needs and the needs of the NCC.

What is being coated?

The answers to this basic line of inquiry might sound confusing but it is entirely fundamental and will essentially underpin the choice of material to be used.
Are you coating steel? Are you coating timber? Do you have low clearances around the steel? Will the steel be hidden from view or visible? Is it a 3 sided piece, a 4 sided piece, how long is the span, how think is the beam, etc?
The questions are numerous, and each one of them impacts the choice of material and the time required.

Is the steel internal or external?

If we are talking steel (and for this piece we will assume we are) it is imperative to know the environment the coating will be exposed to, with many parts to this question including;

  • Is the steel outside or inside outside, including the conditions it will endure; temperature, weather, or foot traffic?

  • Harsh chemical fumes or anticipated splash and spills of chemicals?

  • Will the coating be insulated?

  • Thermal cycling/shock?

  • Any expectation of mechanical damage by machine or human?

  • The existing condition of the steel to be coated.

  • What is the condition of existing coatings?

  

Is the steel being sprayed on or off-site?

Logistics of the application will definitely be defined by the answers to this question—whether shop applied, field applied, or in-situ at an operating plant. If the project methodology calls for off-site application of a coating, then the options available come down to a choice of suppliers for thin-film (such as Nullifire) rather than a choice of materials. The reason is simple, thin-film fire rated products transport much more easily with minimal damage as compared to other alternatives.
Another factor is the speed of construction; Fast-cure or fast-dry coating products will be preferred in case that the speed of project completion is a critical consideration. Where speed is a true factor, coating products with high surface tolerance must be chosen.

What are the aesthetic requirements?

When designing and erecting a structure or building, there are very many different elements to consider. These can range from sloped roofs, decorative columns, roofs for window elements, the list goes on and on. However, hard as it may be to quantify the aesthetic value of building or structure, in the eyes of an owner, this value is real, and as such the process of architectural and engineering planning should identify exactly what elements are non-negotiable with regards to design.
But as with everything that looks good in this world – designing for aesthetics seemingly costs more. So where steel needs to be exposed as part of a large open atrium, the chances are, the cost for building it will increase. In this case you will want a product similar to SC902 which is a low build product which can be top coated, allowing you to design to specification and then style for required interior design.

Consulting with fire-rating experts to know the appropriate intumescent coating

Let’s paraphrase Einstein: If you are given a problem to solve in an hour, spend 55 minutes considering the problem and 5 minutes solving it. In other words, planning is key! The same goes for building and the consideration which should be given to fire rating. Plan ahead so that you have options, don’t make hasty decisions which fail to consider all elements of the project, and thus find you have to back track to find a new solution.
In the instance where you are unsure how to proceed, ask. Experts and specialists ultimately have years of experience doing the one thing you may do a couple of times a year. At Permax, our team work with multiple companies on dozens of projects per year, giving us the expertise we need to help you.
If you need some help, reach out, we are just a phone call away.

This entry was tagged : "Passive Fire Rating", SC902, Tips

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