Page 227 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION 5.11

Stainless steel jackets have the following disadvantages:
1. High initial cost
2. Corrosion cracking where chlorine or fluorine exists
3. Low emittance value
4. Long lead time
There are often strict union regulations requiring that stainless steel jackets over 0.20 in
thick be installed by sheet metal workers. Jackets 0.20 in thick or less can be installed by the
insulation contractor. The insulation contractor is more knowledgeable about this kind of
work, so when job conditions permit, it is usually more cost effective to specify the thinner
thickness to ensure that the work will be done by the insulation contractor.

Wire Mesh
Wire mesh is a little-known jacket material. It is mainly used when a strong, flexible, abrasion-
resistant covering that must be easily removed is needed. It is available in widths from 1 to
43 in (25 to 1075 mm), with 12, 18, 24, and 30 in (300, 450, 600, and 750 mm) used most
often. Common wire diameter of the mesh is either 0.008 or 0.011 in. The thicker wire is
used where greater strength is needed or heavy use expected. The openness of the weave is
expressed in density, which gives the number of openings per inch. Densities of 48 to 130
are used, with 60 being the most common. Material of the mesh can be Monel, Inconel, or
stainless steel. It is attached with lacing hooks or sewn with stainless steel wire. In addition,
it must be secured with either tie wires or metal straps.

Plastic Jackets
Plastic jackets are manufactured in a great variety of materials, including PVC, ABS, PVF,
PVA, and acrylics. Thickness ranges from 3 to 35 mils. The manufacturers should be con-
sulted to determine the criteria necessary to select the best material and thickness for any
particular application. Plastic jackets have the following advantages:
1. Lowest cost of any solid jacket
2. Best resistance to chemical corrosion
3. Excellent resistance to bacterial and fungal growth

Plastic jackets have the following disadvantages:
1. Poor fire rating
2. Low impact resistance
3. Softening at high temperatures
4. Vulnerability to infrared and ultraviolet rays and ozone
5. Cold weather embrittlement

COATINGS, ADHESIVES, AND SEALANTS

There are a large number of products available. Rather than listing them here, the design
criteria necessary to the selection of the proper material will be discussed. Manufacturers
specify where to use specific products, but regulations from government and, in some cases,

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