Avoid 5 Fireproofing Pitfalls

02.06.18   Tiffany D. Vorhies, NACE CIP-2 | More by this Author

Avoid 5 Fireproofing Pitfalls

SME's Christopher M. Buyle, NACE CIP-3, SFSI offers valuable insight on properly applying intumescent fireproofing.

Intumescent fireproofing can be a tricky undertaking, and many owners, construction managers and even contractors don’t realize what they’ve gotten themselves into until it’s too late. Since painting contractors already have the equipment to apply intumescent, they are often assumed to be competent and up to the task. However, these teams typically don’t have a strong knowledge of fireproofing standards and end up failing to apply the material properly, resulting in misses, under or over applied product, curing issues and schedule problems.

SME’s coatings experts are regularly contacted by owners and construction managers when problems occur. Sometimes it is too late and the material has so many issues that it must be removed and the process has to start all over. Other times the issues aren’t as bad, but still lead to significant project delays. With a little help from an experienced consultant, you can avoid these schedule and budget busting issues in the first place.

So what are the 5 most common pitfalls and how can you avoid falling into the trap?

1. Failure to Take Environmental Conditions into Account
Like many other spray applied products, intumescent fireproofing needs to be applied and allowed to cure within a set temperature and humidity range. Often we find the intumescent was applied when it was too hot, too cold or very humid, which will almost always lead to the product not curing as expected. When the product doesn’t cure as fast as the contractor needs it to, they often apply another layer and hope for a better result. In reality, this additional material can prevent the base coat from ever curing properly. This leads to the second biggest application pitfall…

2. Recoating Too Soon
Each coat must be allowed to cure properly before the next coat is applied. Covering it with more material will slow down or prevent the curing of underlying material. There can be many reasons why the product did not cure as fast as expected; most commonly a temperature or thickness issue. You should always perform tests to confirm the level of cure before applying additional product, regardless of the recommended recoat times. As intumescent dries, it hardens.

Make sure to check the hardness before over-coating. This is typically done with a Shore-D or Shore-A hardness gauge. You can also often do a “thumbnail check” in a pinch. If lightly pushing your thumbnail into the coating easily leaves a mark, it is likely still too soft.

3. Product Applied Too Thick
One way to avoid over-coating uncured material is to refrain from applying each coat too thick. If conditions are good and the recommended application rate is followed, intumescent will usually cure properly and you will be able to stay on schedule. Slow cure times are only one side effect of thick application. Mud cracking and runs/sags might also occur. Some manufacturers will allow small cracks in the surface (orange peeling) since the product will expand when it is activated; however, large cracks (mud cracking) could leave steel insufficiently protected, and is unacceptable. Cracks and runs are also unattractive. To preserve the aesthetic value of the coating, they usually must be sanded back down, wasting time and material.

4. Misses/Light Application
Many painting contractors who aren’t familiar with applying fireproofing tend to apply intumescent like they would paint. While they will be sure it looks nice from a distance, if there’s a flange you can’t see from the ground it will often be lightly coated or missed. When applying intumescent, all faces of the member must be covered evenly. AWCI measurement standards require averaging and spot minimums, which prevents the beam from being undercoated on one side and over applied on others. No one spot can be less than 80% of the requirement, and applying it thicker on another face can only be counted as 120% of the requirement. Example: if you are required to apply 100 mils, and the inspector measures 150 mils on the web and 70 mils on the flange, they would fail the beam for being below 80% and only record the max thickness as 120 mils on the web, not 150 mils.

5. Not Scheduling Enough Time
For many jobs, the schedule just doesn’t allow for the proper application of intumescent due to a lack of understanding of this complex application process. Also, depending on the size of the member being coated it is common for the requirement to be in the hundreds of mils. A thinner member heats up faster and therefore needs more insulation. Let’s say a ¼” wall HSS column needs 3-hour rating and the product requires 500 mils to achieve it. This could mean 20 coats of intumescent or more. Even with ideal conditions and perfect application, that’s a minimum of 10 working days to apply. Likely, it could be much longer due to the environmental conditions mentioned above. In this situation, proper temperatures and plenty of airflow are the key factors.

The best way to avoid these five common pitfalls and ensure your intumescent is applied effectively is to work with a trusted consultant early in the process. SME can help you avoid these and other mistakes from the start, preventing the need for costly repairs down the road. For more information, contact SME’s coating experts.

TAGS: Coatings

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