Steel is an integral part of the structure of a building and one of the most common construction materials due to its high strength and durability. However, whilst structural steel is fireproof, the high temperature during a fire can compromise the general integrity of the material. 

 

In this article we will discuss the ways in which fire affects steel and the importance of fire protection of structural steel. 

In order to understand why the fire protection of structural steel is important you have to first understand how steel is affected in the event of a fire. 

Structural steel is designed to withstand high temperatures, but even so it will weaken if exposed to extreme heat. At 425°C steel will begin to soften and at higher temperatures, between 600°C and 650°C, it can pose a risk of collapsing as it loses half of its load bearing strength. 

 

Depending on the material being combusted, a fire can reach temperatures well above that threshold. For instance, a candle can often burn at a temperature above 600°C, while substances like propane can cause a fire with temperatures reaching almost 2000°C. 

 

If a candle flame can reach temperatures high enough to impact the load bearing capacity of steel, you can imagine what a large-scale fire can do. To prevent your building from collapsing during a fire and protect the structural steel framework, it’s essential to ensure it is sufficiently fireproofed. 

The fire resistance of steel is calculated based on three main criteria - every single one of which is essential protecting the structural integrity of a building in a fire. The fire resistance period of a structural element is calculated on the time (measured in minutes) it takes for any of the factors to be jeopardised: 

 

Structural steel fire protection building regulations vary depending on the height and purpose of the building. The standards around this are based on two main documents, namely the Fire Safety: Approved Document B, which is considered the main set of regulations regarding passive fire protection, and BS9999. 

Considering that steel frameworks are such an important element of a building’s structure, there are multiple ways to improve their resistance to fire. They are broadly divided into two categories: reactive or non-reactive, based on whether they react to fire or not. For instance, certain fire resistant materials such as intumescent paints expand when exposed to the heat of an open fire to protect the steel structure underneath. Fire boards on the other hand, protect the steel beams and columns in all conditions. 

 

Intumescent Coating 

In passive fire protection, intumescent paints are one of the most common and cost-effective methods of structural steel fireproofing. This type of paint is composed of chemicals that allow it to swell up when in contact with heat, forming a protective layer around the steel structure. This slows down the fire, delaying the time it takes for it to affect the framework of the building and providing occupants with enough time to evacuate. 

 

Fire Boarding 

Another way of protecting structural steel through fire boarding. This process consists of encasing the steel beams and columns in fire-resistant boards to provide protection in the event of a fire. This type of board is made out of mineral-based fireproof compounds such as gypsum. 

GRJ Contracting are leaders in passive fire protection in the UK. Our team is available to provide expert advice and installation services to answer all your passive fire protection needs. Whether you need structural steel fire protection, fire compartmentation, fireproof insulation or a full fire protection survey. With teams located all over the country, you can rest assured that no matter where in the UK you are, we can help with your fire protection requirements. If you wish to speak to one of our fire protection contractors, don’t hesitate to get in touch today!