What material is used to fill gaps in hot-service calcium silicate insulation?

• A. CP-97
• B. Mastic
• C. Weatherproofing
• D. Protective equipment

Answer: (A)

Filling gaps in hot-service calcium silicate insulation requires a material that can withstand high temperatures and form a durable seal with cementitious insulation. CP-97 is a high-temperature, cementitious gap filler designed for this exact purpose. It cures to a hard, non-shrinking seal that surrounds joints and penetrations, preventing air and moisture from sneaking in and preserving the insulation’s performance on hot lines.

Mastic is a general sealant with more limited heat resistance, so it isn’t the best choice for hot-service joints. Weatherproofing products are meant for exterior protection and not for internal gap filling in insulation, and protective equipment isn’t a sealant at all.