Page 223 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION 5.7

Cellular Glass
Cellular glass insulation (ASTM C 552) is pure glass with closed cell air spaces. This
material has a flame spread of 5 and smoke developed of 0. It also has a 0 perm rating. The
typical k value is 0.38 and the R value is 2.6. A jacket is necessary for abrasion resistance;
the type used depends on the expected severity of service.
This extremely rigid and strong insulation is available for pipe sizes up to 36 in (900 mm)
and 1 to 4 in (25 to 100 mm) thick. Form-fitting covers are used for any standard component.
Flat blocks come in sizes 12 × 18 in (300 × 450 mm), 1-1/2 to 5 in (40 to 125 mm) thick,
and in sizes 18 × 24 in (450 × 450 mm). Factory fabricated shapes can be made to fit spe-
cific requirements. Recommended applications include temperatures ranging from −450 to
+450°F (−265 to +230°C), with limitations based on the type of adhesive used with the
material. Cellular glass is used where an extremely strong and impermeable material is
required. It is also impervious to common acids and corrosive environments, and must be
cut with a saw. It is available either plain or with a variety of factory-applied jackets.

Expanded Plastic Foam
Elastomeric plastic insulation (ASTM C 534) is an expanded foam, closed cell material,
made from nitrile rubber and polyvinyl chloride resin. The typical k value is 0.27 and the
R value is 3.6. This material has a perm rating of only 0.17, and does not require a jacket
except for appearance; it can also be painted. The flame ratings of 50 are valid for all thick-
nesses. For material 1/2 in (15 mm) thick and less, a smoke-developed rating of 100 has
been established; up to 1 in (25 mm), the rating is close to 150. Because of the high rating,
building codes do not allow it to be used in all types of construction. A recent development
has enabled manufacturers to reduce the smoke-developed rating down to 50 or below.
Commonly called rubber, this flexible insulation is available for pipe sizes up to 5 in ips
(DN 125), and 1/2- and 3/4-in (15 and 20 mm) thicknesses. In sheets, it is available in sizes up
to 36 × 48 in (900 × 1200 mm) with 24 × 48 being the most common. Sheet thickness ranges
from 1/8 to 1-1/2-in. It is also available in 48 in (1200 mm) wide rolls, with thicknesses of
1/2, 1/8, and 1 in (15, 20, or 25 mm). Yet another product is a 2-in-wide roll, 1/8 in thick, with
self-sealing adhesive. Recommended applications for pipes include temperatures from 35 to
220°F (1.5 to 103°C), and for sheets up to 180°F (81°C), due to the adhesive required to apply
it to a tank. It is used in pipe spaces and boiler and mechanical equipment rooms, where code
requirements may be relaxed and the ease of application could make it more cost effective.

Foamed Plastic
Foamed plastic insulation is a continuously molded, rigid product made from foaming
plastic resin, which results in a closed cell material. Typical insulation materials are poly-
urethane (ASTM C 591), polystyrene (ASTM C 578), and polyethylene. A factory-applied
jacket is usually provided. The typical k value is 0.15; R value is 6.7.
Due to the possibly wide variations in the composition of the materials that fall into this
category of insulation, the fire rating varies between manufacturers. Although the materials
are combustible, they can be made self-extinguishing. Foamed plastic is recommended for
low temperatures including cryogenic, and for moderate temperatures, generally up to a
maximum of about 220°F (103°C).

Calcium Silicate

Calcium silicate (ASTM C 533) insulation is a rigid material compounded from silica, asbestos-
free reinforcing fibers, and lime. At 500°F (260°C), it has a k value of 0.5 and an R value of
2.0. A field-applied jacket is required. This insulation is commonly referred to as “calsil.”

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