Intumescent Coatings: What Are They & How Are They Used?

Coatings offer much more than the colors you see on your homes or cars. Coatings also take on critical functions. Along these lines, one of the most important types of coatings are intumescent coatings.

Also known as a fire-retardant coating, intumescent coatings are passive coatings designed to protect the products they are on from catching fire. They are used in conjunction with a primer and a topcoat, which helps protect against corrosion while offering the possibility of aesthetic options. Most often, intumescent coatings are used on steel, whether it is for construction, pipelines and sewers, oil and gas production, or other industrial applications where high heat can be a factor.

Roger Soler Palau, group product manager cellulosic PFP, Hempel A/S, sums up the role of intumescent coatings quite nicely: 

“Passive fire protection (PFP) is generally implemented to protect the building itself by insulating the steel structure to maintain the structural integrity of the building for as long as possible… Achieving this will effectively “buy time” for emergency services to attend; for safe evacuation of the building; and for fire-fighters to extinguish the fire.  In short, these passive protection measures will minimise damage, reduce losses and potentially save lives.”

How Do Intumescent Coatings Work?

When a fire or excess heat occurs, intumescent coatings go to work. If heat is generated, a chemical reaction in the coating leads to it forming a foam of non-flammable gases like ammonia or carbon dioxide, forming an insulating layer on the coating.

These layers react, absorbing heat while creating a layer of char up to 50 times the thickness of the coating. This helps slow the spread of the fire and protects the structure’s strength from failure for a longer period of time, which can help save lives as well as the structure itself.

Unfortunately, intumescent coatings can’t solve every fire. The range that an intumescent coating can protect can generally reach 500°F; as was seen on Sept. 11, 2001, when jets were crashed into the World Trade Center, the jet fuel fire reached 1800°F. This was impossible for the coatings to overcome.

Please note that intumescent coatings differ from heat resistant coatings, which do not protect the item from fire. Also, building codes often specify the use of fire-retardant coatings. For example, ASTM E119, “Standard Test Methods for Fire Tests of Building Construction and Materials,” offers methods to measure the time and temperature that a structure can withstand fire.

Where Might Intumescent Coatings Be Used?

As mentioned above, intumescent coatings are most often found on steel, but these coatings are versatile, and can be found on wood, concrete and other substrates. For example, intumescent coatings can be found on home and commercial buildings, as they offer protection while also adding aesthetic elements. Steel beams and supports, columns and supports are areas where intumescent coatings are applied.

Intumescent coatings are more likely to be considered as part of the industrial coatings family. Pipelines are one such use. As fluids are pumped through faster, it creates greater friction, leading rising heat. The same goes for oil and gas rigs.

Intumescent coatings are a sizable market. Many of the world’s largest paint and coatings manufacturers, including PPG, Sherwin-Williams, Hempel, and Carboline, are in this segment, as well as some niche specialists such as FlameOFF Coatings.

Are There Different Types of Intumescent Coatings?

Intumescent coatings vary in composition and usage across industries.

• Water-based intumescent: Water-based formulations offer eco-friendliness and reduced odor. While cost-effective, they may take longer to cure in high humidity or low temperatures, making them suitable for indoor applications where curing time is not critical.

• Solvent-based Intumescent: Solvent-based coatings provide resistance to weather and temperature fluctuations, drying quickly with a smooth finish. They are commonly used in semi-exposed environments where durability and rapid drying are essential.

• Epoxy-based Intumescent: Epoxy-based formulations excel in harsh conditions like offshore marine or chemical industries, offering superior hydrocarbon fire protection and corrosion resistance. Typically applied in two parts, they form a thick, durable film that insulates steel members effectively.

What are the Key Ingredients of Intumescent Coatings?