Fireproofing Methods for Structural Steel
Steel loses approximately 50% of its load-bearing capacity when it reaches 1,000oF (537oC). Accordingly, all structural steel buildings and industrial plants with human occupants must be protected from fire events to allow rescuers time to evacuate structures.
Fireproofing can be active, or passive. Active fireproofing consists mainly of sprinkler systems, gases or other means of automatically extinguishing the fire. Passive fire protection consists of sacrificial layers applied to the surface of steel elements in order to provide time for extinguishing the fire or evacuating occupants before structural collapse.
Fire protection is typically specified considering two potential events consisting of cellulose or hydrocarbon events. Cellulose consists of wood fires that develop heat slower and generally develop less overall temperatures. Cellulose fire protection is assessed using a gradual oven test temperature that achieves 2,000oF (1093oC) in four hours. Cellulose protection is utilized in schools, residential, hospitals and commercial structures.
Hydrocarbon consists of aggressive fuel and chemical fires that develop higher heat faster. Hydrocarbon fire protection is assessed using an expedient test oven high temperature of 2,000oF (1093oC) within five minutes and maintaining that temperature for the entire duration of the test.
Other fire exposure protection and testing can consist of Jet Fuel, Pool Fire, Blast and Hose Stream testing. It is, therefore, important for engineers to understand the fireproofing requirements they must meet and the structural steel fireproofing options available.
Structural Steel Fireproofing Code Requirements
The rating of structural components or fireproofing systems is typically expressed as an hourly rating. For example, if a two-hour fire rating is required, the system or construction elements will need to meet the requirements for a two-hour rating in a standard ASTM E119/UL263 (cellulose) or UL1709 (hydrocarbon) fire-resistance test. Fire resistance directories can be used to determine the fire-resistance ratings of various building elements, such as in the directory provided by Underwriter’s Laboratories.
The requirements for any given construction project will vary based on a number of factors, including intended use, location and design. To establish the required fire resistance ratings for your project, consult your local building code, refer to model building codes and/or refer to structural/architectural design requirements.
Structural Steel Fireproofing Methods
In order to meet passive structural steel fireproofing code requirements, there are a number of methods available.
Spray-Applied Fire-Resistive Material (SFRM)
The most common fireproofing method in the United States is to apply a spray-applied fire-resistive material (SFRM). Typical SFRMs are composed of cement and gypsum and may contain other materials such as mineral wool, quartz, perlite or vermiculite. The fireproofing is applied as either a wet or dry spray, or may also be trowelled on to the required thickness.
SFRMs are typically used when fireproofing steel beams or columns. While not its primary use, SFRMs may also provide an added benefit in the form of acoustical or thermal insulation.
However, SFRMs are not usually suitable for surfaces with high exposure to moisture or humidity, which can deteriorate the product. This can make it difficult to use in areas with high humidity or where there are freeze-thaw cycles. Most SFRMs provide little to no independent corrosion inhibition for steel elements and other relative protection must be provided. The surface preparation (blasting, primers, lath/attachments, etc.) for most SFRMs can be costly and time-consuming.
Intumescent fire-resistive material (IFRM) coatings are another fireproofing material for structural steel. A thin layer of an epoxy-based mixture is applied to the surface. When heated, this coating chars, foams and expands — up to 100 times its original thickness — creating a barrier between the steel element and the fire.
One of the benefits of intumescent paint is its lightweight characteristic and its corresponding ability to be used on exposed steel surfaces, without compromising design.
However, intumescent products are highly vulnerable to environmental exposure during the application, which can limit their performance. The cost of intumescent coatings is also much higher than other options, with the cost increasing the higher the fire rating required.
Intumescent products typically contain inherent corrosion inhibition for steel elements. The surface preparation (blasting, primers, lath/attachments, etc.) for most IFRMs can be costly and time-consuming.
Rigid Board Fireproofing
Rigid Board Fireproofing involves installing a rigid fire-resistive board to beams, columns and deckings. Rigid board fireproofing can be used in out-of-sequence construction phases so that it can be installed “as-you-go.” Rigid board fireproofing can also be used in many environments, including places with freezing weather conditions and with a variety of substrates.
However, rigid board fireproofing tends to be a more expensive and slow to install option, which can impact tight project budgets and timelines. Rigid board fireproofing provides no independent corrosion inhibition for steel elements and other relative protection must be provided (blasting, primers, galvanizing, corrosion-resistant paints, etc.).
Flexible Blanket Systems
Flexible blanket systems offer combined fire, thermal and acoustic insulation and produce no toxic smoke at high temperatures. They are a lightweight and versatile product that can be easy to install even on complex shapes.
However, there is no customization available with flexible blanket systems — the product thickness is set by the manufacturer. The products also require additional fasteners as part of the installation. Finally, there are limited manufacturers of these products.
Flexible blanket systems provide no independent corrosion inhibition for steel elements and other relative protection must be provided (blasting, primers, galvanizing, corrosion-resistant paints, etc.).
Concrete and masonry used to be one of the most common methods for fireproofing structural steel. These days, Portland concrete is mainly used to encase large areas of steel such as when fireproofing steel columns.
However, traditional concrete fireproofing of structural steel requires a larger volume of space, has a high carbon footprint and is not design-friendly. Portland concrete fireproofing provides little to no independent corrosion inhibition for steel elements and other relative protection must be provided (blasting, primers, galvanizing, corrosion-resistant paints, etc.).
Geopolymer Fireproofing Methods
The traditional methods that have been long-used in the construction industry often have drawbacks and cannot be used to meet the design or fireproofing needs of projects across a wide range of environments and complexity.
That’s why Geopolymer Solutions created Cold Fusion Concrete® FP250, a spray-on fireproofing for steel. The innovative engineering behind Geopolymer Solutions revives and reimagines ancient methods used by the Romans to create the next generation of SFRM.
Our patented geopolymer concrete technology is a high-density, Portland-free fireproofing material, and it is unlike any other commercially available product. FP250 can be applied to any size steel, overhead and vertical — and it’s never been easier to use spray-on fireproofing for steel beams, columns and systems.
FP250, up to a 4.5-hour fire rating, can be applied in a single one-pass layer, saving you time and providing significant value for money compared to other products of a similar rating.
FP250 boasts a number of benefits, including:
- Withstands extreme heat without degradation
- Highly abrasion-resistant
- Highly impact-resistant
- Highly resistant to acids, solvents, chlorides and sulfates
- Able to withstand weathering and resistant to freeze-thaw cycling
- Long-life span (estimated up to 10 times that of traditional Portland cement concrete)
- No need to blast, prime or use mesh reinforcements or corner beads
- Installs extreme inherent corrosion inhibitors
- Already passed UL1709 5th Edition Requirements
- Exceeds many technical specifications
The superior strength and durability of FP250 make it highly recommended for applications where safety is paramount, such as petrochemical plants, power plants, schools, hospitals, and military and dock facilities.
By using 50-60% recycled materials, no volatile organic compounds and using no Portland cement in our manufacturing, FP250 is an eco-friendly product that can reduce your carbon footprint. This may be of great help with obtaining LEED certifications.
FP250 bypasses all the challenges of traditional fireproofing options, providing an easy-to-use, cost-efficient, environmentally-friendly and high-performing solution.
Make sure your project uses the best fireproofing on the market. To learn more about the difference between FP250 and traditional methods of steel fireproofing, contact us