What is a common insulation material used on cold lines?

• A. Fiberglass insulation
• B. Fiberglass wrap
• C. Polyethylene foam
• D. Asphaltic mastic

Answer: (A)

When insulating cold lines, the goal is to minimize heat transfer into the pipe and prevent surface condensation. Fiberglass insulation does this well because its fibrous material has low thermal conductivity, providing strong resistance to heat flow for the thickness used. It’s also practical and economical, available as blankets or boards that can fit around straight sections and fittings, and it accepts a protective jacket plus a vapor barrier to keep moisture from wicking in. With the jacket and barrier in place, the pipe stays closer to its intended temperature, reducing energy losses and the risk of moisture-related issues. Other options exist—fiberglass wrap is just another form of the same material, polyethylene foam offers moisture resistance but isn’t always the preferred choice in all cold-line installations, and asphaltic mastic is a sealant, not insulation, so it doesn’t provide the needed thermal resistance.