Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
FLEXIBLE LAMINATED THERMAL INSULATION
This invention i5 concerned with laminated
flexible thermal insulation jackets for hot and cold
pipes, vessels, tanks and ducts. Jackets constructed
according to the invention also afford corrosion and
flash fire protection for pipes, vessels, tanks, ducts,
etc., and afford flash fire protection when used over
walls, roofs, panels, etc.
A wide array of materials have been employed
lo or suggested for use as jacketing and thermal insulation
for a number of different reasons, including a neater
appearance, protection against the weather and fas-
tening the insulation to pipes. Alone or in various
aggregations, these materials have included aluminum
and other metallic casings, canvas, asbestos paper as
well as coatings of numerous resinous materials. One
example is a laminate composed of polyvinyl flouride
on a neoprene-impregnated asbestos felt~ Another type
of commercial insulation covering material employs
fiber glass yarn patterns as a reinforcement between a
flame-retardant kraft paper and the face of aluminum
foil to ~hich that paper is bonded. The foil may have
a pigmented vinyl resin coating on its other face.
The reinforcing yarn patterns are usually rather pro- i
minently visible on both sides of the products. Also,
the pigmented coating reduces the reflection of heat
7 by the aluminum layer.
The flexible laminated jackets of the instant
invention utilize known sheet materials, but two of
these have apparently never been employed as elements
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of a composite jacketing material. Moreover, the pres- -
ent combinations and arrangements provide unusual and
improved combinations of desirable results, including
some of an unexpected nature.
Accordingly, the present invention provides
a flexible laminated thermal insulation jacket, the - `
improvement comprising a thin film of heat reflective
metal on the internal face of a synthetic resin vapor
barrier film. The present invention also provides a
fire-resistive flexible laminated thermal insulation
jacket, the improvement which comprises a layer of
felted asbestos fibers containing a binder resin and
reinforcing glass fibers.
Other aspects of the invention are concerned
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with more specific details, combinations or embodiments
which may involve such items as a layer of mass-type `
of insulating material bonded to the insulation jacket,
a vapor barrier film of a linear polyester resin (e.g.
transparent polyethylene tereph~halate), a reflective
aluminum coating on that film, a binder xesin (eOg.~
polyvinyl chloride) in the asbestos layer, fiber glass
scrim ~loth in the asbestos layer~ and a fluorocarbon
resin, especially a polyvinyl fluoride film9 as the
external surface layer. ~-~
! Still other aspects of the invention as well
as its benefits and advantages will be apparent to
those skilled in the art upon consideration of the
following detailed discloæure.
FIG. 1 shows one embodiment of an article
of the invention in a greatly enlarged sectional view
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1 wherein relative thicknesses of the layers in the
composite jacket material are somewhat distorted for
the purpose of clearer illustration.
FIG. 2 is a fragmentary longitudinal sec-
tional view of another embodiment of an article of
the invention.
FIG. 3 is a fragm~ntary greatly enlarged sec-
tional view on the same plane of details of the sama
artlcle wherein relative thicknesses of the layers are
somewhat distorted for the purpose of clearer illustra-
tio~.
FIG. 4 shows another modification in a sec-
tional view similar to FIG. 2.
The jacketing materials of the present inven-
tion are composite or laminar articles comprising at
least two, and preferably tnree, principal layers of
a flexible nature that are flexibly bonded into a
unitary sheet material suitable for covering flat sur-
faces and surfaces having simple curves.
A composite jacket 8 shown in FIG. 1, and also
in FIG. 3 with additional layers 9 and 10, is con-
structed by adhesively bonding the entire adjacent
faces of three preformed sheet materials into an in-
tegral jacketing material having an improved combina-
tion of properties relative to prior art jackets. In
this emhodiment, the interior surface layer intended
for contact with conventional thermal insulation sur-
rounding a pipe, etc., or with the bare pipe itself
in some applications, is a vapor barrier layer in the
forrl of a polyester resin film 1 bearing an ultrathin,
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vapor-deposited coating 2 of aluminum on its internal
face. The metal side or face of this metalli~ed resin
is bonded by the adhesive 3 to one face of a central
layer 4 of asbestos paper in which is embedded a rein-
forcing layer 5 of open mesh fiber glass scrim cloth.
Layer 4 also preferably contains a binder resin.
-- Another adhesive layer 6 serves to cement the other
face of the asbestos layer 4 to the inner face of an
exterior surface layer 7 of polyvinyl fluoride ilm.
`` Although it is contemplated that the interior
surface layer 1 of resin may be omitted in some embodi-
ments of this invention when a vapor barrier is not
needed, the resulting composite thereby loses some de-
sirable qualities. The tough resin film 1 serves to ~-
- protect the asbestos layer 4 against physical damage;
it provides a convenient, economical and commercially
available carrier for the metal coating, a very light
weight, flexible and efficient heat reflecting form of
insulation; and it protects one side of the thin metal
layer 2 against corrosion by sealing the resin side of
the metal coating against exposure to any vapors, gases,
- and liquids. Such corrosion would greatly impair the
efficiency of the layer 2 in reflecting heat radiation~
A wide variety of plastic compositions may
be utilized for the surface film 1 in meeting the re-
quirements of forming a film that is a suitable sub-
strate for vapor metallization and that displays a low ;
permeability for water vapor ~- for example, low enough
for a composite jacket rating below about 2 perms, and
preferably as low as possible. Linear polyesters, the
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poly~eric reaction products of dihydroxy alcohols and
dibasic organic acids may be used. Excellent results
are obtainable with metallized polyethylene terephtha-
late film which exhibits very low permeability for
water vapor and high dimensional stability in combina- `
tion with good heat resistance. A resin that is trans-
parent is preferred for obtaining the full benefit of
the metal coating as a heat reflector.
It is also contemplated that other resins
may be used for film 1 as exemplified by polyvinyl ;
chloride~ polyvinyl fluoride, other fluorocarbons, and
even copolymers of vinyl chloride and vinylidene r
chloride in applications where shrinkage is no problem.
The metal coating may be any metal capable of
reflecting heat and of being applied by conventional
vapor deposition procedures to form a mirror-like
coating 2 on the resin film 1. Thus, the metal may
be aluminum, chromium, copper~ nickel, silver, gold,
etc.~ or alloys of these or other metals. Aluminum is
generally preferred for good results and economy.
Preformed polyethylene terephthalate film with a vapor
deposition coating of aluminum on one side is currently
available in adequate quantities at reasonable cost.
The thickness of the metallized vapor barrier -
layer 1 may range widely~ for instance from about 0.25
to 4 mils (thousandths of an inch)~ but it is typically ;~
between about 0.5 and 1.5 mils. The thickness of the
vapor-deposited metal layer 2 is negligible~ usually
being ultrathin coating of less than 0.01 mil~ Although
ultrathin, the metal layer 2 provides a much lower vapor ;~
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permeability in the metallized resin film than dis-
played by a plain resin film.
The felted fibrous layer 4 can be any fibrous
waterproof mat, but is pre~erably seaple glass mat, or
asbestos paper formed from a slurry of individual asbes-
tos fibers in water on a traveling wire screen simi- -
larly to paper-making operations. The reinforcing
glass scrim cloth 5 is introduced at the proper inter-
val in the process for a mid-depth location while the
asbestos fibers are settling on the screen. Also~ it
- is desirable for the slurry to contain a binder mate-
rial, such as a latex of rubber or polyvinyl chloride,
that remains flexible and increases the strength of ~`
the paper. A flexible polyvinyl chloride binder is
generally preferred for its self-extinguishing com-
bustion p~operty, and it may be present in an amount
of about 10 to 30% ~preferably about 15-20%) of the
dry weight of the asbestos layer.
Layer 4 is the bulkiest layer in the com- `
posite, being typically about 15 to 30 mils thick.
This bulk is helpful in minimizing "telegraphing" of
the pattern of scrim cloth on the surfaces of the
jacket material~ However, the fibrous asbestos layer
may be as thick as 40 or more mils or as thin as about
10 mils depending considerably on the desired coef-
ficient of conductive heat transfer through the jacket
as well as its desired fle~ibility. Both properties
are mainly dependent on the thickness of the asbestos
layer.
The scrim cloth 5 may be woven from polyethylene
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l terephthalate or nylon threads where the strength of
the jacket at high temperatures is not important, but
fiber glass threads are usually preferable. The ~eave
of the cloth may have a thread count of from 2 X 2 up
to 12 X 12, and an 8 X 8 count is typical.
The exterior skin or surface layer 7 is a
continuous or unbroken flexible film of a solid resin
as exemplified by polyvinyl chloride for indoor usage
and fluorocarbon resins or acylic resins1 such as
polymethyl methacrylate for general usage. The fluoro-
carbons are preferred for most purposes, but the ex-
pensive chlorotrifluoroethylene and tetrafluoroethylene
polymers seldom, if ever, justify their extra cost over
polyvinyl fluoride. The latter is being manufactured
in the ~orm of strong films of 0.5 to 4 mil thickness
with various pigments incorporated therein. Polyvinyl
fluoride film is an extremely durable preformed finish
layer for exposure to all types of weather, common sol-
vents strong cleaning agents, corrosive liquids and ^
gases.
Polyvinyl fluoride film is desirably ren-
dered surface receptive to adhesive bonding by surface
activation on both of its faces as may be accomplished
according to the teachings of United States Patent Nos.
3,133,854; 3~228,823; and 3,369,959. Those patents
disclose pertinent background on surface activation
and some of the aclhesives for activated polyvinyl ;~
fluoride surfaces. In addition to the epoxy resins,
vinyl addition polymers, polyalkyl acrylates
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1 and other adhesives mentioned therein, one may employ
the cements based on synthetic rubbers as described
in United States Patent No. 2,376,854. In general an
elastomeric adhesive is preferred for forming flexible
bonds between the flexible layers. The aforesaid ad-
hesives may be employed as the bonding age~ts for both
faces of the central asbestos felt layer 4, that is
in both of the thin layers 3 and 6. In the case of
adhesive layer 6, even when the exterior resin skin
lo 7 is pigmented, it is often desirable, for maximum -
resistance to deterioration from prolonged exposure
to sunlight, to incorporate an agent capable of re-
sisting such degradation in the adhesive. Such agents
are well known and exemplified by the carbon black men-
tioned in certain of the aforesaid patents or an ultra-
violet absorber, such as a compatible suhstituted --
benzophenone or substituted benzotriazole selected
from those listed in the chart on pages 1008-1009 of
the 1969-1970 Modern Plastics Encyclopedia of Breskin
Publications, Inc., Bristol, Connecticut.
FIG. 2 is a fragmentary general cross-section
through the thickness taken in the machine direction
or longitudinal plane, of another embodiment of the in-
vention. It shows a thin, relatively dense laminar
jacket 8 to which is bonded a series of contiguous dis-
crete strips ~ of inorganic fibrous mat thermal insula-
tion. FIG. 3 is an enlarged sectional vie~ on the same
plane of the same embodiment as in FIG. 2. It depicts
the adhesive layer 10 binding the strips 9 to the
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composite jacket 8 which is composed of the layers
designated by reference numerals 1 to 7, inclusive.
The insulating material in layer 9 serves
to minimize heat transfer by conduction; hence it is
a relatively bulky material containing a substantial
volume of voids or dead air space. Flexible polyure-
; thane foams or other flexible foamed resins with
suitable temperature characteristics may be used for
the purpose. However, mat insulations constructed
essentially of inorganic fibers, such as glass fibers
and mineral wool, are often preferred. They are inco~-
bustible and can be employed over a wide-range of
operating temperatures. Also, costly ceramic felt in-
sulation may be used in some special cases, as where
" .
unusually high temperature conditions justify the extra
expense. ~ `
Strips 9 may be obtained from relatively -
rigid conventional inorganic fiber batts or boards ; ` `
which are impregnated with conventional binding agents~
For example, typical fiber glass boards with densities
of about 0.5 to 2 or more pounds pfr cubic foot and
thicknesses of about 0.5 to 2 inches or more may be cut i `
into strips of about 0.5 to 2 inches width of uniform
rectangular cross-section for rearrangement as strips
9 in the present composite articles. Substantial
flexure is usually involved in fitting the products of
this invention to pipes and other curved surfacesO
However, flat fiber glass boards or batts do not pos-
sess the necessary flexibility for bending in the trans- `
verse direction or any other direction~ because the ~
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individual fibers or strands are deposited in chopped
form in a sequence of parallel layers each on top of
the preceding layer and then immobilized with a binding
agent. There is random orientation of the fibrous
material within each of the parallel layers but rela-
tively few fibers are oriented in depth to extend
through any or all of the layers; hence the orienta-
tion of the fibers may be described as essentially
planar with the fibers being disposed predominantly
within a series of substantially parallel planesr As
a result, the insulation board or batt is relatively
stiff and its surfaces cannot be stretched or reduced
in length or width as is necessary in bending a sheet
material of substantial thickness. However, this board
can be compressed and reduced in thickness, iSe., in a
direction substantially normal to the planar fiber
alignment. In the present articles9 the strips 9 are
disposed in a way that reorients the planes of fiber
orientation so that these planes are substantially `;
perpendicular or normal to the surfaces of the new
laminated article rather than parallel thereto. Such ;
reorientation of the fiber planes can be expressed as
substantially normal to the laminar jacket and paral- -
lel to one another. Thus with the strips 9 aligned
in that manner and bonded to a sheet of flexible
jacketing material 8, the composite sheet may be
flexed with the strips 9 being compressed and be-
coming narrower during concave flexure of that side
of the composite sheet.
~he adhesive 10 used for bonding the
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mass-type insulation 9 to the surface of the laminar
jacket may be a hot melt adhesive or one of the adhe-
sives disclosed hereinafter incLuding epoxy resins9
and synthetic nitrile rubber modified with a phenol-
formaldehyde resin, as well as others known in the art.
Hot melt adhesives often contain a relatively low
molecular weight substance of the group consisting of
ester or paraffin waxes, and rosin, alkyd, terpene and
coumarone-indene resins blended with a limited pro-
portion of such higher molecular weight polymers as ;~
polyvinyl acetate, polybutyl methacrylstes, polyethy
lene, polyisobutylene and polystyrene along with a
liquid plasticizer~ Among the formulations recommended
for general hot melt bonding are mixtures of polyethy-
lene, polyvinyl acetate and polyamide reaction prod- ~
ucts of dimerized fatty acids and diamines. ~ -
Another embodiment of the ~acketed insulation ~ ;~
of this invention is illustrated in FIG. 4 wherein a
very thin aluminum foil 20 is interprosed in the mass
insulation to reflect heat radiation. In this partic-
ular modification, each of the fibrous mat strips 9 is
composed of two sections 18 and 19 bonded to opposite
faces of the foil 20 with an adhesive known in the art
as effective both on aluminum and on glass or mineral
wool fibers. The sections 19 and 20 are cut from the
same types of fibrous boards or batts as the unitary
strips 9 in the embodiment of FIGS. 2 and 3, and the
fiber orientation relative to the laminar jacket 8
and the bonding are also similar. In general, the foil
20 is employed as a primary heat reflector along with
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the metal coating 2, and there is some evidence that
` this structure can result in a surprising reduction
. in the skin temperatures of outer layer 7 from those
obtained under comparable conditions with a jacketed
insulation &omposite differing only in the omission
of the foil 20.
To illustrate the method of forming a specific -
composite jacket material according to this invention,
an adhesive coating is applied to one of the two acti-
vated faces of a 1.5 mil thick web of a suitable com- .
mercially available polyvinyl fluoride by passing the
~ . .
web through a conventional coating device containing ~ ::
: a solution of a synthetic rubber adhesive of the buta- :
diene-acrylonitrile type in a naphtha-based solvent, ;:~
which is also commercially available. Next, the adhe-
sive coating is dried during travel of the web through
. an oven; then the coated side of the plastic web is :
laminated in contact with one face of a web of a
25-mil thick suitable asbestos paper product that is
advantageously reinforced, as by an internal glass j
: fiber scrim cloth of 8 x 8 count and including a poly-
vinyl chloride binder resin~ The bonding is accom- ,.:
plished by passage of the assembled webs through nip . .
rolls with an unheated rubber roll bearing on the
exposed polyvinyl fluoride face while a heated steel
roll bears on the asbestos paper side7 Thereafter, in .
similar procedures, a suitably metallized 0.9 mil web
of polyethylene terephthalate is coated on its metal-
lized face of vapor-deposited aluminum with the same
synthetic rubber adhesive, oven dried and laminated
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onto the asbestos face of the asbestos-polyvinyl
fluoride composite in the same nip rolls.
The particular jacketing material produced
in the aforesaid procedure has an overa~l thick~ess-of
25 mils~ the same as the original thickness of the
reinforced asbestos layer, as a result of the com- i
pacting of that layer by the nip rolls. It possesses
a tensile strength that is usually well in excess of
50 pounds per inch of width and a vapor barrier rating
of 0.02 perm (water transmission in grams per hour per
square foot per inch mercury pressure differential~
The composite material may be successfully employed in ~ ~-
covering thermal insulation having surface temperatures
ranging from far below zero (e.g., -200 F) up to 325 ~-
375 F range, and the maximum temperature can be ex-
tended to 400F or more when the vapor barrier resin - -
layer 1 is omitted from the lay-up.
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In addition, the aforementioned laminate has
greater flame resistance than pure aluminum which melts
at approximately 1220F and is the most common jacket
for outdoor pipe insulations. The new composite has
successfully withstood oven temperatures of 1500F with
the glass reinforcing threads remaining intact, shielded -
by the asbestos; and there are indications that it will
withstand higher temperatures and may provide fire re-
sistance at temperatures ranging up to about 2000F~
Still other properties and advantages of such jacket
material are set forth hereinafter.
The instant composites may be used for covering
practically any type of thermal insulation, including
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` 1 calcium silicate, foamed glass and ceramic materials,
- such plastic foams as polyurethane and polystyrene
; foams, corrugated asbestos paper, fiber glass and
mineral wools in batts and blankets, etc. These
- jackets can be employed for covering such kinds of
insulation on pipiny systems, tanks, vessels, ducts
and almost all types of insulated equipment. It may
be desirable in some instances to cover bare pipes
and other uninsulated surfaces with the present jack-
ets, for example, as protection against corrosive
liquids and gases as may be encountered in chemical
plants, etc.
To make the compo,ite article shown in FIG.
3, l-inch thick fiber glass boards with a density ap-
proximating 2 pounds per cubic foot and a temperature
rating of 850F are cut transversely into strips of 1
inch width. A coating 10 of a.conventional hot melt
adhesive, as mentioned earlier, is applied in the
molten state to the exposed face of the polyester film
1 o: the web of jacketing material. After being reori-
ented, the fiber glass strips are bonded with their
lengths disposed transversely (i.e., crosswise or op-
posed to the machine direction) of that web and in
firm contact with adhesive coating 10 while it is
still in fluid state. Th~e reorientation involves
rotating each strip 90~ about its length, so that the
parallel planes in which the glass fibers are predom-
inantly disposed are substantially normal to the web
or surface of the jacket; also it is desirable for
convenient roll storage that these planes extend
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- 1 transversely of the web. Scrips 9 are parallel and
preferably in contact with one another, but they are
des:rably discrete with no substantial adhesive bonding
between their contiguous sides. After cooling of the
adhesive, the resulting jacketed insulation may be
flexed and bent into substantial curves around axes
transverse to said web without cracking, buckling or
forming unsightly wrinkles.
In addition to the convenience of fitting a
complete insulation as a one-piece material, one or `
adjacent or separated strips 9 may be removed entirely
a substantial part of the depth thereof in solving
difficult problems of fitting the insulating material
around tight bends, small diameter pipes or in crowded
locations. .:
The composites of this invention can be
easily fitted and fastened with the resin film 7 on
the outside as the exposed surface layer and the vapor
barrier resin layer 1 in direct contact with the surface ~ -
of the insulation or the surface to be covered. Only
simple conventional hand tools, such as scissors or
knife, ruler, stapler and brush, are needed. The
joints are generally overlapped and cemented with a ;
contact adhesive (e.g., a synthetic rubber-phenolic
resin type) which will bond the overlapping several
inch wide margin or portion of resin layer 1 to the -
underlying marginal area of the bondable surface of
resln layer 7, (e.g., an activated fluorocarbon
resin surface) of the jacket. Alternatively, the
overlapped seam may be fastened with staples, desirably
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1 made of monel or other corrosion-resistant alloy; but
it i 5 often preferable to both staple and cement the
jOi.lts. In applications where a vapor or liquid
barrier is necessary or desirable, or where the ap~
; pearance of the installation is critical, the staples
and overlapped seams may be sealed with a suitable tape.
A tape matching the exterior resin layer 7 is generally
preferred; for instance, co~ering and sealing an exte-
rior film of polyvinyl fluoride with a polyvinyl
fluoride tape of the same composition, color and thick-
ness and two-sided activation, but also bearing a
coating of a pressure-sensitive adhesive which is pro-
tected by a readily releasable paper liner. The prior
surface receptive treatment of the polyvinyl fluoride
film assures durable adhesion of the adhesive face of
the tape to both the exposed surface of the exterior
layer of the jacket and to the uncoated surface of the -~
tape itself.
The unique combinations of structural features .;
in the present composite jackets provide outstanding
combinations of desirable properties and larger numbers
of such benefits than were available in prior art jacket
materials, including some advantages which are unique.
Moreover, certain of the structural arrangements pro-
duce complementary or cooperative effects. For illus-
tration, in the asbestos layer 4, the embedded glass
fiber strands of scrim cloth 5 greatly reinforce the
strength of the felted asbestos but they have a much
lower melting point and flame resistance than the
asbestos; however, the asbestos covers and insulates
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1 the glass fibers, and this protection enables the
glass fibers to reinforce the asbestos layer, even
when the surface temperatures of the outer face of
the asbestos exceed the softening or melting tempera-
ture of the glass fibers. These complementary pro-
tective effects are particularly significant in instal-
lations where flash fires may occur and it is important
to shield pipe or equipment surfaces from contact with
flames. Without the reinforcing fiber glass threads,
the asbestos paper would tend to collapse or tear as
the resin binder could be decomposed by the heat from
a flash fire.
~- Similarly, the internal disposition of the
metal coating 2 enables its covering transparent resin
- layer 1 to protect the metal against corrosion from
acid, alkaline, oxidizing or other corrosive substances
(e.g., during careless storage or from the alkali pres-
ent in some insulating materials) and thus to maintain
its efficiency in reflecting heat radiation. Another
cooperative effect resides in the fact that the metal
coating greatly enhances the vapor barrier effect of
the resin film and permits obtaining very low perm
~-~ ratings with a very thin and flexible metallized resin
film. For instance, the mo:isture vapor permeability
of uncoated polyethylene terephthalate film is typically
^~ of the order of ten times that of the same film bearing
an ultrathin coating of va~r-deposited aluminum.
The inhalation of air-borne dust particles or
fine fibers of asbestos is considered to be an occupa-
tional health hazard for workers handling asbestos. In
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1 the composite of the invention, the surface layers 1
and 7 completely cover the faces of the asbestos layer
4 and thereby minimize or eliminate any hazard for
personnel applying it to insulation or any other sur-
face. Moreover, in a preferred embodiment of the in-
vention using an asbestos paper impregnated with a
substantial amount of a flexible binder agent, the
asbestos hazard is likewise minimized or eliminated `~
for workers making and using the present laminated
jackets. A flexible asbestos paper impregnated with
a latex of either rubber o~ polyvinyl chloride can be
soaked in water without the delamination which occurs
with untreated asbestos paper. Polyvinyl chloride is
the prefexred binder in view of its self-extinguishing
combustion property. The fibrous asbestos serves as
the major insulating component within the jacket for
minimizing conductive heat losses as well as providing
outstanding flame resistance.
The exterior skin 7 provides resistance to
the weather and soiling from various causes, and in
the case of fluorocarbons, there is outstanding re-
sistance to wind, rain, snow, sandstorms and micro-
organisms. For example, the preferred polyvinyl
fluoride film is tough, abrasion-resistant and inert,
so it is unaffected by substantially all of the
strongest common cleaning solvents and detergents,
acids and alkalis at room temperature, and usually
at elevated temperatures. Its pigmented modifications
are generally unmatched in fade resistance and strength
retention under outdoor conditions or buried in soil. ~;
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1 In addition, it has a low moisture absorption of only
0.5~, coupled with high tensile, tear, impact and
burst strengths; also it is suitable for continuous
use at 225F and its zero strength temperature is in
the 500-570F range.
The present compo.,ite jackets have an excep-
tional array or combination of properties that provide
an ~musually wide field of ~se in efficiently jacketing
hot or cold equipment or its thermal insulation under
any atmospheric or soil burial conditions as well as
most corrosive conditions likely to be encountered.
In addition to their suitability for continuous use
at substantially elevated t.emperatures for periods
that are expected to exceed 20 years, the new jackets
have an unusual degree of f.ire resistance in respect
to retaining their basic configurations at very high
temperatures and displaying desirably low smoke ratings.
These laminated jackets are tough and flexible enough
so that they may be walked on without cracking or loss
of vapor barrier properties; and they resist scuffing,
abrasion and accidental punctures as well as tearing
from stapling. Thus, they do not present the main-
tenance problems of conventional jackets, mastics,
etc.. Also, the instant jacket materials require.no
painting or repainting, and any surfaces that are
soiled, greasy, or contaminated with fungi or bacterial
growths from external sources can readily be cleaned .
and/or disinfected, without damage, by using powerful
agents including steam, hot water with soap, or strong .
detergents, all commercial organic solvents and
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1 disinfectants. The instant insulation jackets can also
be removed for repairing jacketed pipes and equipment
and subsequently replaced in an installation that sub-
stantially matches the oriyinal in efficiency and neat
appearance.
In the preferred embodiment described herein
the layer 4 is described as an asbestos felt or paper
containing reinforcing fibers. Many other fibrous mats ;
would be suitable as long as they resist deterioration
when exposed to water or water vapor, for example,
fibrous mats made from glass fibers, ceramic fibers
including carbon fibers, and/or synthetic organic
fibers such as polyester and nylon fibers.
While only a few embodiments of the present
invention are described in detail herein, for purposes
of a concise disclosure, it will be apparent to those
skilled in the art that other modifications of such
articles are within the purview of the invention.
