For many owners of industrial facilities, an industrial fireproofing strategy is a prerequisite for being able to secure affordable insurance. But despite being just short of mandatory for many businesses, straight advice on what type of industrial fireproofing strategy to pursue can be hard to come by. Many online sources tend to dispense advice that seems curiously tailored to their own product lines upon closer inspection.
Here, we’ll lay out what we as industrial fireproofing applicators consider to be the most effective solutions. But we need to define a couple of terms before we dive into one of the liveliest debates in industrial fireproofing: cementitious versus intumescent coatings.
Active vs. passive fire protection
Two terms that come up often in discussions of a facility’s fire protection are “active” and “passive” fireproofing. Active fireproofing (AFP) measures are all of those that require some type of action, either triggered by ambient conditions or an individual, in order to be effective. Examples of AFP include the kicking on of a sprinkler system or a staff member using a fire extinguisher to try to put out a small blaze. Your local fire department and the brave work they do is perhaps the finest example of AFP.
Passive fire protection (PFP), on the other hand, refers to building design elements and planned safety measures meant to control the spread of a fire. PFP can help to mitigate the potentially disastrous effects of failed AFP measures, like broken sprinklers or an extinguisher that hasn’t been inspected or replaced in a timely manner. Examples of PFP measures can include room compartmentalization to prevent a fire’s spread, fire doors to limit the spread of smoke and, most importantly for our purposes, a fire-resistant coating that helps to protect structural steel and limit damage to critical infrastructure.
One strategy is never a substitute for the other, but PFP can help to hedge against unexpected AFP measures and to buy time for them to kick into effect, hopefully helping to alleviate the effects of a fire event within a facility. Now we can take a look at what sets two of the most common types of PFP, cementitious and intumescent coatings, apart from one another and which factors should determine their use.
Cementitious or intumescent coatings?
Lightweight cementitious coatings have their origins in the dense concrete that was often used to fireproof industrial facilities up until around the mid-twentieth century. Cheap and resistant even to very high temperatures, dense concrete was eventually superseded by cementitious coatings that were not quite as heavy (and hence were cheaper and easier to apply) once the technology developed.
Today cementitious coatings remain relatively inexpensive materials for the fireproofing of facilities. Though labor does have the potential to drive up the cost of these jobs, since they must be applied in several, successive layers, they are still well-suited for dry environments where the substrate is not expected to be exposed to heavy vibrations and/or impact.
Where they should not be used is in environments with high ambient moisture levels, since cementitious coatings will inevitably create a space between the substrate and the coating itself. This space is ideal for moisture to settle and for the process of corrosion under fireproofing (CUF) to set in.
Intumescent coatings operate on a different principal, however. Rather than forming a relatively thick physical barrier between the flames and the steel they protect, as cementitious coatings do, intumescents “intumesce”, or char and expand, when exposed to extreme heat. The coating literally grows as a means of forming the type of barrier that cementitious coatings maintain regardless of temperature. By increasing in volume and decreasing in density, intumescents slow the heating of steel and prolong the possible response time before a significant failure or collapse occurs.
Intumescents have the added advantage of being much easier to apply than cementitious coatings. In fact, they are applied in much the same way a traditional coating is applied, with much less of an opportunity for moisture to settle in between the coating and the substrate. Additionally, successive layers of intumescents can be applied to increase the time the coating is able to protect steel from extreme temperatures even further. The number of layers, and consequent degree of PFP, is determined during the specification phase and is often directly correlated to the consequences of a failure resulting from a fire event.
Cementitious coatings remain a viable solution for fireproofing facilities under some circumstances. As relatively inexpensive materials, they can be a smart solution where conditions allow. But intumescent fireproofing is far more advanced from a technical standpoint, carries with it some benefits of being applied like and behaving as a traditional coating, and offers the flexibility of added fire protection where necessary.
All PFP measures are simply design elements meant to buy time for AFP measures to take over and subdue the blaze. But that doesn’t mean they’re unimportant. On the contrary, they can make the difference between a damaged facility and one that is beyond repair.