MSSA

INTUMESCENT FIRE PROTECTIVE COATING FOR STEEL

Intumescent fire protective coatings are widely used as passive fire protection in oil and gas industries, civil buildings, chemical plants and other facilities in developed countries. Intumescent coatings are composed of three fire retardant additives: an acid source (such as ammonium polyphosphate), a carbon source (such as pentaerythritol), and a blowing agent (such as melamine) bound together by a binder. The formulation of the coating has to be optimized in terms of physical and chemical processes in order to produce an effective protective char layer upon exposure to fire [1,2]. As yet, in Malaysia there is a lack of extensive research in the field of fire protective coatings and of awareness of its role and ability in the containment of fires. This coating is typically applied on steel structures to maintain the structure properties below the critical temperature of 550°C (Fig. 1) [3].

Figure 1. The steel structures coated with intumescent coating.

Indeed, prevention of the structural collapse of the building is paramount to ensuring the safe evacuation of people from the building, and is a prime requirement of building regulations in many countries. Current commercial intumescent coatings are very costly due to the materials used and will incur immense additional expenses in the building and construction line. Besides that, intumescent coatings are not as frequently used as active fire protection due to lack of knowledge and exposure to its potential as a highly effective fire protection that is able to reduce the rate of fire spread. This fire-resistive coating has the capability to protect structural buildings from extensive fire damage, while at the same time offering additional benefits to the coated substrates including water resistance and corrosion protection. The main objective of this project is to develop a highly effective fire-resistive coating to maintain the steel's integrity and properties between 1-3 hours of fire exposure at temperatures below 500ºC, which may well prevent or delay structural collapse.

At present, research in intumescent fire-resistive coating for steel has been done by M.C. Yew & NH. Ramli Sulong (2012) studied the behavior of protected and unprotected steel plates in a fire test [4]. The variation of temperatures recorded from the protected and unprotected steel plates during the heating and cooling phases of the furnace test were compared to the furnace and Eurocode fire curves (Fig. 2). The difference between the temperatures of the protected and unprotected steel plates increased to almost 450 °C after about 22 min. The furnace test results show that the steel plate with fire protection could maintain its integrity and properties (Fig. 2a) whereas the steel plate without fire protection exhibited severe deformation due to loss of strength and stiffness (Fig. 2b).

Figure 2. Time–temperature curves of (a) protected and (b) unprotected steel plates [4]

The intumescent fire protective coating on the steel formed an insulating multi-cellular layer on heating (Fig. 3a), which acts as a thermal barrier that effectively protects the substrate against fire. Fig. 3b shows the residue obtained after the test.

This intumescent coating is applicable to all industries, since it addresses fire-safety which is of paramount importance in the preservation of lives and assets. The usage of this coating improves the fire-safety features of structures which not only increases its value but also protects its occupants.

Figure 3. The intumescent coating (a) during and (b) after the Bunsen burner test [4]

References [1] S. Bourbigot, M. Le Bras, S. Duquesne, M. Rochery, Recent advances for intumescent polymers. Macromolecular Materials Engineering, 289 (2004) 499. [2] K. Wu, Z.Z. Wang, H.J. Liang, Microencapsulation of ammonium polyphosphate: Preparation, characterization, and its flame retardance in polypropylene, Polymer Composites, 29 (2008) 854-860. [3] S. Duquesne, S. Magnet, C Jama, R. Delobel, Intumescent paints: fire protective coatings for metallic substrates, Surface Coating & Technology 180-181 (2004) 302. [4] M. C. Yew and N. H. Ramli Sulong. Fire-resistive performance of intumescent flame-retardant coatings for steel, Materials & Design 34(2012) 719-724.