Exploring Insulation Materials

August 1, 2012

Phenolic

Phenolic
insulation is rigid foam insulation with a closed-cell structure. It is
manufactured as large rectangular buns typically 4 ft. wide x 3-12 ft. long x
1-2 ft. tall at a density of 2 lbs/ft³. Prior to actual installation, buns are
fabricated into various shapes, including flat boards and preformed pipe
half-shells 3 ft. long, and designed to fit over NPS pipe and tubing. More
complex shapes can also be fabricated to fit around fittings, elbows, and other
equipment. ASTM material specification C 1126, Type III, Grade 1 covers this
type of insulation at service temperatures from -290°F to 257°F.

The specification defines requirements for density, compressive
resistance, thermal conductivity, water absorption, water vapor permeability,
and dimensional stability. While this ASTM spec lists two grades and three
types, only the Type III, Grade 1 is appropriate for use in pipe insulation.
The other types are boards, either faced with a vapor retarder or not, and used
for building sheathing and roofing, respectively. Grade 2 is an open cell
product. For comparison purposes, the maximum thermal conductivities at 75°F
for the Type III, Grade 1 phenolic insulation is 0.13 Btu-in/hr-ft²-°F.

Key
applications for phenolic insulation are on pipe, equipment, tanks, and ducts,
especially those operating at temperatures below ambient.