FOCUS
Designing competency Having experienced good and bad practice with intumescent coating design,Bob Glendenning discusses safety concerns arising from a lack of competency
M
Y PAST experience of design saw me working within the steel fabrication and design community for almost 20
years, followed by the last 15 years working in the intumescent paint industry for coatings manufacturer Sherwin-Williams. In this time, I have experienced examples of both good and bad practice in intumescent coating thickness design, so wanted to explore why I feel compelled to write this article on the grounds of safety concerns. Intumescent coatings form one member
of the family of solutions available for the fire protection of structural steelwork. Steel has been pivotal in my entire career, but until joining the complementary industry of protecting it in case of fi re, I, along with many other practising design engineers, was blissfully unaware of the challenges faced. Such coatings have become hugely popular
in the UK, as well as many other parts of the world, in particular because they can be used architecturally to express structural steel. They have contributed to the freedom of design, allowing projects and buildings to be more interestingly shaped and fully glazed with the steel frame
16 MARCH 2018
www.frmjournal.com
on show. You need only look at the London skyline to see how these fantastic buildings have grown in popularity and imagination in recent years. Many of these structures are protected with our FIRETEX coatings. In a fi re situation, as steel becomes hotter it
starts to lose some of its properties. For instance, it loses stiffness at a surprisingly low temperature (from 100 to 150 degrees Celsius), and later starts to lose its yield strength (from 400 degrees Celsius). If it is left unprotected, structural steelwork could reach 400 degrees within fi ve to ten minutes.
An intumescent coating protects the steel’s
structural properties by providing insulation in a fi re. The coating swells to form an insulating layer of char, which slows down the rate at which the steel’s temperature rises. This provides the desired time period to allow evacuation, and for fi rst responders to control the fi re. Unlike other forms of protection, it is more
critical to the performance of this life safety coating that the design of the applied thickness is carried out correctly. Put simply, if the thickness is not correct, then the fire protection is likely to be inadequate.
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