Page 225 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION 5.9

treated papers, and papers laminated with foils and/or cloth), and mastic. Jackets can be
specified separately or factory applied. Separate jackets are used for special situations when
a factory-applied jacket is not available or possible, for example, jackets made of aluminum
or plastic sheets. The factory applied jacket is by far the most common and is available in
three types: the so-called all-purpose jacket, which has a vapor barrier; a plain jacket; and
a weatherproof jacket.
Each manufacturer has a different combination of materials that are laminated to each
other to provide flexibility, strength, and fire resistance. Kraft paper that has been coated
or treated with chemicals is the most common base. The next layer is usually fiberglass
cloth, used for strength, and the third layer is usually an aluminum foil. All three layers are
permanently bonded together with a special adhesive to give the desired strength and water
vapor retardation characteristics.

All-Service Jacket (ASJ)
The all-purpose, or all-service, jacket has a vapor barrier. The complete jacket is a lamina-
tion of kraft paper, fiberglass cloth (skrim), and either aluminum foil or metalized film. This
is commonly referred to as an FSK jacket, for foil, skrim, and kraft.
The kraft paper is a bleached 30-lb (13.5-kg) basis weight material, which means 30 lb
2
2
(13.5 kg) for each 30,000-ft (2790 m ) area (or one ream). There is also a 45-lb (20.2-kg)
basis weight paper available if a heavier paper is desired.
The fiberglass scrim is used for strength and reinforcement of the paper. The standard
weave is 5 × 5, which means five lines per inch. Other weaves are available, ranging from
1 × 1 to 10 × 10, and also a 10 × 20. Also available is a bias weave, which adds diagonal
threads in a third direction. The closer the weave, the stronger the jacket.
The foil used is aluminum, ranging in thickness from 0.35 to 1.0 mil. The standard
thickness is 0.50 mil. Metalized film is also available. Although thinner than foil, it retains
its shape better under impact. One manufacturer described its product as a white, metalized
polypropylene film with a perm rating of 0.02.
The composition of the adhesive and the actual methods used to bind the components
together are proprietary. It is the adhesive that imparts the fire resistant rating to the entire
jacket system. After a layer of adhesive is applied to the kraft paper, the scrim is added and
the adhesive forced through the weave. Finally, the foil or metalized film is put on next. The
three layers are then laminated together to form the complete jacket system.

Lagging

Lagging is the process of insulating a pipe or vessel and then covering the insulation with a
cloth jacket. The jacket is primarily used to improve the surface appearance of any insula-
tion, offering very little in the way of protection. Lagging materials are available in a full
spectrum of colors and may eliminate the need for painting. This cloth can be canvas or
fiberglass, for example, and is secured to the insulation with lagging adhesive and/or sizing.
Also available is a combination system that serves as both an adhesive and protective coat.

Aluminum Jackets
Aluminum jackets (ASTM B-209) are available in a corrugated or smooth shape and in
thicknesses ranging from 0.010 to 0.024 in, with 0.016 in being the most commonly used.
Also available are different tempers or hardness. These range from H 14 (half hard) to
H 19 (full hard), with H 14 being the most common. Aluminum jackets can be secured by
one of three different methods: banded by straps on 9-in centers, by a patented seam in an

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