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Uses of Cast Epoxy Intumescent
Circular Hollow Sections
The premier use for cast epoxy intumescent is to offer the designer a unique and secure system of fire protection to decorative steel columns—both internal and external—that usually occupy the most prestigious areas of a building. Interact’s cast epoxy intumescents for circular hollow sections are known as Interactive Columns.
The properties of cast epoxy intumescent make secondary cladding for Interactive Columns completely redundant.
With no design joints or screw fixing, the result is a seamless, slim circular section that allows for the greatest possible use of floor space. This makes it particularly appropriate for heavily populated and open areas like an atrium, shopping mall, or airport terminal.
Although it does not rely on any finishing coat to protect against water or chemical attack, a wide range of surface finishes and colours are also available to further enhance the overall appearance. Special anti-graffiti protection can also be applied.
Interact recommends a particular range of Top Seal Finishes.
Quality Control
The casings are factory made and each shell is checked for roundness, thickness and imperfections before it is primed ready for installation. The casing is packed and sent out with a protective inner and outer layer to ensure the finished product arrives on site in good condition.
With the casings arriving already cast, there is no opportunity for an inquisitive subcontractor to spoil the finish by pressing on the surface when it is only half-cured (as with thin-film intumescents).
Interactive Columns are installed by trained craftsmen with an eye for decorative perfection. Joints and seams are virtually undetectable. Wherever possible, installers will be FIRAS approved personnel. The flexibility of when installation can actually take place also contributes to overall quality control. The inherent robustness of the product means that it can be installed at any point in the construction process—from the initial development phase to just prior to commissioning. This is particularly helpful to ensure that dry weather conditions are prevailing at the right time.
To understand the full procedure, take a look at the details in the installation process.
Other Architectural Features
Interact can cast their epoxy intumescent into almost any shape. Therefore, an aesthetically pleasing solution can be provided to almost any architectural feature … without any compromise to the fire protection integrity.
Rectangular Hollow Sections
In addition to the standard circular columns, Interact can cast epoxy intumescent into components suitable for the cladding of rectangular columns. Because the epoxy intumescent requires no expansion space to be left between the steelwork and the exterior finish (to allow for expansion in the event of a fire), the finished rectangular column has smaller dimensions than those protected by other methods.
Suspension Rods and Hangers
Cast epoxy intumescent sections can also be used successfully to fire protect suspension rods for up to two hours. It can achieve an aesthetically acceptable result even on narrow diameter rods—something virtually impossible with other fire protection methods.
Thin film intumescent can protect most suspension rods to 60 minutes though the specifier should refer to the manufacturer of the thin-film for confirmation. However, it is not always possible to achieve protection for such periods as 90 minutes and above. There is also considerable risk that the standard of finish and robustness of a thin-film system may not be suitable for the project.
Nodes
It may be necessary to fire protect the joint nodes. The node may require periodic inspection for signs of stress and thin-film intumescent will conceal any early signs of stress and therefore may not be suitable as a form of fire protection. An alternative method of providing access is to box out the node in a fire protection board, ensuring access by means of a removable panel. Architects and designers may wish to resist this when they have put so much effort into making a feature out of the node design. This is also likely to be the case with junctions and cleats.
Cast epoxy intumescent can be moulded to any shape and produced to the same specification and decorative finish as that for the column. Nodes can also be manufactured with replaceable plugs to allow for the inspection of any sensitive area of the junctions. Nodes need to be assessed on an individual basis to ensure the fire test data is not compromised. Interact will provide all the technical assistance required to assess each situation.
Abutments
With any building structure, there will be numerous abutments to the steelwork. The flexibility of Interact’s epoxy intumescent—both in terms of its ability to be cast into any shape and the inherent benefit that all joints are virtually invisible—means that any abutment can be adequately and attractively fire protected.
Triangular Hollow Sections
From experience, it is evident that triangular sections cannot be treated in the same manner as other CHS and RHS structures. Unless the manufacturer has specific fire protection test data, standard thin-film intumescents are not suitable for triangular sections even for a 60 minute period.
Fire protection to triangular hollow sections can however be properly provided using cast epoxy intumescent.
Boxed I-Sections
There are occasions when the architect may wish to give a building a different impression to the one intrinsically created by the structural steelwork. In such a situation, Interact can cast their epoxy intumescent to give the impression of underlying features that aren’t really there. For example, a standard tapered beam can be made to look like a boxed I-section, giving the building a feeling of greater robustness.
Cast Iron
Fire protection legislation of buildings with cast iron columns only comes into play when the building is being refurbished or subject to a change of use. It is important to be aware that test data for the basic performance of cast iron columns is at best ambiguous. Interact believes it is best practice to assume accurate test data either does not exist or is inconclusive. Therefore, when specifying fire protection for cast iron columns Interact recommends erring on the side of safety, whatever the chosen solution, and using fire protection considerably in excess of what would be specified for an equivalent steel column.
For more information and advice on fire protection for cast iron, please contact Interact Head Office.
The benefit of using Interact’s cast epoxy solution is that custom castings can be made to maintain the inherent characteristics of a building whilst bringing the fire protection up to date. Indeed, there is nothing to stop intricate details such as gargoyles being cast from epoxy intumescent.
Special Projects
Blackwall Tunnel
The properties and versatility of cast epoxy intumescent make it ideal for unorthodox applications where traditional methods of passive fire protection cannot be effectively deployed.
Interact’s help in coming up with a particular solution for the Blackwall Tunnel is good example. The tunnel had just been refurbished and upgraded. Part of the upgrade was to improve the fire protection to the service duct that runs alongside the road at ground level. Access to the top of the service duct provides sanctuary in case of accidents—and is provided by foot holes in the duct wall. This wall must remain smooth as any accident may result in a vehicle scraping along it.
The previous recommendation had been to apply 7 mm of epoxy intumescent to the four internal sides and back face. The material would also be applied to the front flange. This proved to be impossible to carry out with any acceptable degree of accuracy.
Interact put forward an alternative that was authenticated by Leigh’s Paints, the raw material manufacturer who carries the necessary test data to support it.
The solution involved the manufacture of cast blocks that would sit at the back of the foot plates. At 30 mm thick and with an intumescent value of 7 x the thickness, the material is calculated to fill the whole of the void and provide the required insulation to prevent the inside of the service duct from reaching 140°C.
This was not the only solution sought. There was also a requirement to prevent the service duct from reaching 140°C in the event of a low-level fire over a longer period of 4 hours. Although there was already a degree of insulation created by the intumescent blocks, this was not sufficient to protect the duct for that long. The extra solution was to laminate a technically superior insulation to the back of the block. This material was developed adapting the same technology used to produce Kevlar (common in many military applications).
“Interact provided helpful assistance in designing different alternatives to enhance the fire protection in and around the service duct at Blackwall Tunnel. Anthony Tiernan, the MD, assured us that he would find a more suitable solution, produced a scheme and worked with Leigh’s Paints to establish the approval.
Interact provided a list of approved sub-contractors, and the company was also on hand in the event of any problems occurring during installation. In the end event, the contract went very smoothly and was completed on schedule.”
Elim Church (Bristol)
Whilst Interact’s cast epoxy intumescent was specified to provide the fire protection for the steelwork in the church, in this special case it wasn’t just their fire protection properties that made Interactive Columns the right product to install.
With only a 30 minute fire protection requirement, a number of potential alternatives were available to the architect. However, as the internal furniture of the building is constantly being rearranged, a solution was required that was aesthetically desirable yet could also stand up to the daily knocks and abuse it would encounter.
In particular, it was stipulated that there should be no ‘orange peel’ texture to the finish of the columns as results with the application of thin-film intumescent. The superior appearance of Interactive Columns, together with the inherent robustness of the system and its extreme ease of repair (in the event of any real damage occurring) meant that there could only be one possible choice.