When would a drill bit be used for SFRM inspection?

• A. When thickness testing low density SFRM
• B. When thickness testing high density SFRM
• C. During bonding testing
• D. Never used in SFRM inspection

Answer: (B)

Drill bits are used to obtain a physical core for exact thickness measurement when the sprayed fireproofing is high density. High-density SFRM can be too thick or too irregular for some non-destructive gauges to read reliably, so extracting a core provides a direct, measurable thickness from the surface to the substrate. For low-density SFRM, non-destructive methods often give sufficient accuracy, so drilling isn’t routinely needed. This method isn’t used for bonding tests, which are a different type of inspection. So, using a drill bit to check thickness is specifically tied to high-density SFRM.