Which of the following is an example of TSI (Thermal System Insulation)?

The selection of cementous mud around pipe fittings as an example of Thermal System Insulation (TSI) is accurate because TSI is specifically designed to reduce heat loss or gain in mechanical systems. This form of insulation is typically applied to pipes, tanks, ducts, and similar components to maintain temperature by minimizing heat transfer.

Cementous materials, including cement asbestos insulation, are often used in industrial applications for insulating high-temperature pipes and equipment, which qualifies them as TSI. The primary function of TSI is to enhance energy efficiency in buildings and processes by providing effective thermal resistance, thereby making cementous mud an appropriate representative of this category.

Conversely, the other options provided—fiberglass insulation in walls, vinyl flooring, and wood paneling—serve different essential functions. Fiberglass insulation is more associated with building envelope insulation rather than specific thermal systems. Vinyl flooring does not fit under the category of thermal system insulation as it primarily serves as a surface covering. Wood paneling also does not function as thermal insulation in the context of heating systems but serves decorative and protective purposes. Thus, cementous mud around pipe fittings is the clear example of TSI in context.