CA1326215C

CA1326215C - Insulated pipe apparatus

Info

Publication number: CA1326215C
Application number: CA 600661
Authority: CA
Inventors: Charles Edwin Weir
Original assignee: FEDRICK RONALD MICHAEL
Current assignee: FEDRICK RONALD MICHAEL
Priority date: 1988-05-25
Filing date: 1989-05-25
Publication date: 1994-01-18
Anticipated expiration: 2011-01-18

Abstract

INSULATED PIPE APPARATUS
ABSTRACT OF THE DISCLOSURE

An insulated pipe apparatus including an inner conduit for carrying fluids wherein insulating material surrounds the inner conduit and extends substantially the length of said inner conduit. The insulating material is formed of a sheet of approximately trapezoidal sections defined by "V"-shaped grooves which when wrapped around the inner conduit form a circumferentially and longitudinally contiguous sleeve along the length of the inner conduit. A rigid outer casing resistant to mechanical stress and moisture ingress is disposed coaxial and coextensive with said inner conduit and surrounds the insulating material. Means defining a plurality of longitudinal elongated voids of substantially constant cross section and coextensive with said insulating material is disposed between the outer casing and the insulating material. Interconnecting means for interconnecting the elongated voids and sealing the ends of the insulating material are disposed between the outer surface of the inner conduit and the rigid outer casing.

Description

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FIELD OF THE INVE~TION
This invention relates to an insulated pipe apparatus for use as a conduit in a high or low temperature fluid distribution system, and more particularly to a method and means of manufacturing an insulated pipe apparatus with an insulation system that is easily manufactured and which is readily adapted for use in a wide variety of thicknesses each for a wide variety of conduit diameters.

~ACXGROUND OF THE INVENTION
Insulated pipe structures are commonly used in heat distribution systems, where hot fluid or steam is distributed to a desired location, or in cryogenic applications. These systems can be used in residential or industrial applications such as heating buildings or maintaining the temperature of a particular system.
In one prior pipe apparatus described in U.S.
Patent No. 4,700,751, an insulated pipe apparatus includes an inner conduit for carrying fluids. Insulating material in the form of a sleeve surrounds and extends substantially the length of the conduit. A plurality of elongated voids are defined around the insulating material. A fibreglass reinforced rigid outer casing surrounds the voids. The elongated voids are continuous and are of constant cross-section and means are provided for sealing the ends of the pipe apparatus.
While pipe apparatus described in the above U.S.
patent has proven useful, it requires a sleeve of insulating material which is formed with an internal diameter which substantially matches the outside diameter of the inner conduit. Since this type of insulated pipe is manufactured in a wide variety of diameters, manufacturers must maintain an inventory of LCD:gg --1-- ~

, ` ~32~2~ -insulated sleeves in a variety of sizes. These sizes may vary from a 1" diameter pipe with insulation thickness from 1" through 6" to a 36" pipe with insulation thickness from 1" to 12" (in 1/2 increments). Therefore, an inventory of literally hundreds of sizes is required. Maintaining this inventory i5 expensive, and in many ca~es an insulated sleeve of a desired size may not be available when desi~ed, An object of the present invention is to provide a method and means of manufacturing an insulated pipe apparatus in a wide variety of sizes and having all of the advantages of the pipe apparatus described in the above-referenced U.S. patent while maintaining an inventory of insulating material-in a relatively few sizes.
Another object of the present invention is to reduce the cost of manufacturing an insulated pipe apparatus.
Another object of the present invention is to provide a drainable, dryable, pressure testable, preinsulated pipe apparatus with enhanced insulative properties and improved consistency.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages will become apparent upon reference to the detailed description of the invention and the accompanying drawing wherein:
Figure 1 is a view in perspective of a prior art insulating sleeve.
Figure 2A is a view in perspective of the present insulating sleeve prior to processing.
Figure 2B is a view in perspective of the preferred embodiment of the insulated sleeve of the present invention.
Figure 3 is a cross-sectioned view of an . ; ~ .

~ ~3262~5 insulated pipe apparatus constructed with the insulated sleeve of the present invention.
Figure 4 is a cut away view in perspective of the insulated pipe apparatus of ~igure 3.
Figures 5A and 5B show alternative preferred configurations for venting, drying, draining and air testing ports extending from an annular void through an end seal to external equipment.
Figure 6 is a cut away view in perspective showing an insulated pipe apparatus with an attached end cover.
Figure 7 is a cut away view in perspective of an alternate embodiment of the present invention.

8U~laRY OF THE INVENTION
Briefly described, the present invention comprises an insulated pipe apparatus which includes a substantially cylindrical inner conduit for carrying fluids. Compressible insulating material surrounds the inner conduit and extends substantially the length of the inner conduit. The compressible insulating material is formed of a sheet of approximately trapezoidal sections defined by "V"-shaped grooves which when wrapped around the inner conduit form a circumferentially and longitudinally contiguous sleeve along the length of the inner conduit. A rigid outer casing resistant to mechanical stress and moisture ingress, is disposed coaxial and coextensive with the inner conduit and surrounds the compressible insulating material.
A means defining a plurality of longitudinal elongated voids may be disposed between the outer casing and the compressible insulating material, wherein the elongated voids are of substantially constant cross-section and coextensive with the compressible insulating material. Interconnecting means for interconnecting the elongated voids and sealing the ends of the insulated pipe apparatus are disposed between the outer surface of the inner conduit and the rigid outer casing. The present invention further LCD:~g --3--~,~$~

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contemplates the use of coupling means for connecting the inner conduit to external equipment.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is adapted for use withan insulated pipe apparatus of the type described in U.S. Patent No. 4,700,751 by substituting the present insulating sleeve with the insulating sleeve described - therein. Referring now to ~igure 1, a prior art insulating sleeve is shown in perspective. In prior insulated pipe structures, insulated sleeves are constructed in sizes which match particular diameters o conduits. In other words, for each diameter of conduit, an insulated sleeve having a matching inner diameter is required. In addition, for each inner diameter size, a number of insulation thicknesses are required. The most common insulated sleeve is shown in Figure 1, wherein ~ the insulated sleeve i5 formed in two matching sections 12, 14 which are joined at seams 16 over the inner conduit 18 peior to encasing the structure. Since each sleeve half is subject to various manufacturing tolerances, the butt edges which comprise seams 16 do not close completely, thus allowing heat dissipation through the seams.
Referring now to Figure 2A, the present invention contemplates the use of a single molded flat sheet of insulating material 20 which may typically be approximately 6 inches thick prior to preparation. The sheet 20 is then cut or sliced along line 21 to a desired thickness as required by a particular application. The present invention also contemplates the use of several standard thicknesses of single molded flat sheet of insulating material 20 that can be directly "V"-grooved for wrapping around inner conduit 22. In the preferred practice of the present invention the insulating material 20 may suitably be constructed with mine~al ~vl, urethane foam, foam glass, fiberglass :

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or calcium silicate insulation boards which are available from many insulation manufacturers. A
plurality of "V" shaped grooves 26 are then cut in sheet 20 as shown in Figure 2B. The "V" shaped grooves allow the sheet 20 to be wrapped around inner conduit 22. "V"
grooved insulating boards have been offered in the past for use in field applications on bare pipes. However, this material is not suitable for use in a pre-manufactured inslllated pipe because it lacks the required structural integrity offered by the surrounding enveloped corregated material 3B and because the "V"
grooves in field application material are prone to heat loss. The present invention overcomes this problem by using a comp~essible insulating material and disposing the vertical angle of the walls 28 defining the "V"
groove at an angle which allows the walls 28 to compress against each other when the insulating board iæ wrapped around inner conduit 22 as shown at junctions 30. In the preferred practice of the present invention, the walls 28 are disposed at an angle of 10 to 15 degrees with.respect to the vertical axis of the ~V" groove.
When insulating board 20 is completely wrapped around inner conduit 22 the junctions 30 are under compression thus providing improved structural integrity and improved insulation at junctions 30. In addition to the above, the insulating qualities of the insulating board 20 are further improved because of the additional radial compression of the insulation caused by the tension of the glass filaments 39 as they wrap around the corregated material 38 squeezing it against the insulation 30 during the filament winding process as will be discussed in more detail below.
Once in~ulating board 20 is completely wrapped around inner conduit 22, it is ready to be assembled in accordanc~ ~7ith the method described in U.S. Patent No.
4,700,751 and which is explained by reference to Figures - - - . , .

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3 and 4. The pipe appacatus 32 includes an inner conduit 22 for carrying fluids. The inner conduit 22 may be composed of fiberglass, PVC plastic, copper, steel, steel alloy or other types of pipe materials.
Insulating material 20 is wrapped around inner conduit 22 in accordance with the scheme described above. A
rigid outer casing 34 surrourlds in~ulating material 20.
The rigid outer casing 34 is preferably formed of reinforced fiberglass manufactured in accordance with the teachings of U.S. Patent No. 4l700,751.
The pipe apparatus 32 further includes means 36 1 fnr creating a plurality of elongated voids between casing 34 and sleeve of insulating material 20. Means 36 shown in Figures 3 and 4 comprises a corrugated material 38, preferably made of fiberglass to resist moisture penetration and corrosion and to increase mechanical strength. It extends substantially the length of casing 34. The cocrugated material 38 includes ridges 40 which define continuous and constant cross-section voids 40 which extend along the surface of insulating material 38 for substantially its entire length. The voids thus formed enable the free flow of air for venting, drying, air testing of the pipe apparatus and for the free flow of moisture for draining the voids. This increases the insulative properties of -the apparatus and decreases the likelihood of corrosion of the inner conduit.
The insulated pipe structure 32 is readily adapted for use with the end seal shown in Figure 6 and the coupling and interconnecting means shown in Figures 5A and SB for innerconnecting the continuous elongated voids 40, for constructing insulated pipe structures of desired lengths, and for coupling the insulated pipe to external equipment. The interconnecting means comprises an annular void 46. The corrugated material 36 terminates a sho~ dis~nce froln the inner face of disk ~ - -13~62~

52 of end seal 44. The insulating material 22 and the rigid outeL casing 34 extend beyond the co~rugated material 36 and contact the inner face of the disk 52, thus defining the annular void 46. The end seal 44 preferably is in the form of a cap comprising the disk 52 and a cylindrical sleeve S4. The disk 52 is sealed to the end of the rigid outer casing 34 and covers the entire cross-section of the insulated pipe apparatus except for the inner conduit 22 which passes through central opening 56 in the disk 52. The inner conduit is sealed around its circumference to the disk 52. The inner face of the disk 52 defines one side of the annular void 46. The cylindrical sleeve 54 is continuous with the disk 52 and surrounds and is sealed to the rigid outer casing 34. Heat in the inner conduit is dissipated by conduction to the disk 52 and thence to the cylindrical sleeve 54. This protects the rigid outer casing 34 from thermal damage.
As discussed in ~.S. Patent No. 4,700,751, the rigid outer casing 34 is composed of fiberglass rein.forced material which is a composite consisting of a matrix of resin in which fibrous reinforcements are contained. Commercially available glass fibers have a tensile strength of between 250,000 to 800,000 p.s.i.
Polyester resins are used to bind the fibers in a rigid structure. The resins are the poly-condensation products of dicarboxylic acids and dihydroxy alcohols.
Organic peroxides are used to catalyze the polyester resin and initiate the copolymerization reaction. The peroxides decompose to reduce the free radicals. These free radicals are attracted to points by unsaturation (reactive sites) and initiate the polymerization reactions. This increases the casing's ability to prevent moisture from entering the pipe apparatus and from coming into Col:t~Ct wittl the insulating material 14. That ability i~ pecially usef~ll in underground 132621~

situations where, as pointed out earlier, water is almost always present. In above-ground applications, ultraviolet inhibitors are added to the resin to resist damage from the sun.
The rigid outer casing comprises several wrappings or layers of this fiber-resin matrix. The fiber reinforcing is spirally wrapped in layers as illustrated irl ~igure 4. Filaments 26 are wound in such a way so as to maximize their strength to resist buckling while minimizing the weiqht of the outer casing. Using a Netting analysis, it has been found that the helix angle of the filaments should be approximately 55 degrees and more precisely 54.75 degrees, in order to best compensate for the difference between hoop (radial~ stresses and longitudinal stresses.
Pigures 5A and 5B show preferred coupling means for the connecting annular void 46 with external equipment, whether the annular void is defined by cutting back the insulating material 22 or the corrugated material 36. The coupling is achieved by use of a plurality of tubular ports 48 which extend from the annular void 46 through the disk 52 or through the cylindrical sleeve 54 of the end seal 44 and terminate outside the end seal. The ports are sealed around their circumference to the disk 52 or to the cylindrical sleeve 54 and preferably terminate with a threaded or other configuration suitable for reversible connection to external equipment such as gauges, compressed gas supplies, etc.
The pipe apparatus according to the present invention preferably has a gel coat applied to the outer surface of the rigid outer casing 34. The gel coat is made from isophtalic acid polyester resins which are thickened by the addition of the thixotropic agents, such as aerosil. Pigments and ultraviolet inhibitors .,~

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g are also added in above-ground applications. This chemically links with the substrate and provides the ! insulated pipe apparatus of the present invention with I added resiliency, long life exposure properties, and ! aesthetic appeal.
Referring now to Figure 7, the present invention is also adapted for use in insulated pipe structures whlch do not require the draining and venting means described above. In the embodiment shown in Figure 7, the insulating material 22 is wrapped around the inner conduit 20 in the manner described above. The ~5 outer casing 34 is then disposed in direct contact with insulating material 22 such that the insulating material is in radial compression as described above. The struc~ure is then fitted with an end seal 44 of the type shown in Figure 6. Sections of insulated pipe may be coupled by joining the inner conduits of the various insulated pipe sections.
In summary, an insulated pipe with improved insulation has been described. Accordingly, other uses and modification will be apparent to a person of ordinary skill in the art without departing from the scope of the present invention.

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Claims

1. An insulated pipe apparatus comprising:
a substantially cylindrical inner conduit for carrying fluids; -compressible insulating material surrounding said inner conduit and extending substantially the length of said inner conduit, said compressible insulating material being formed of a sheet of approximately trapezoidal sections defined by "V"-shaped grooves which when wrapped around said inner conduit form a circumferentially and longitudinally contiguous sleeve along the length of said inner conduit; and a rigid outer casing resistant to mechanical stress and moisture ingress, coaxial and coextensive with said inner conduit and surrounding said insulating material.

2. The apparatus of Claim 1 wherein said "V"-shaped grooves are formed at an angle which causes said compressible insulating material to compress when wrapped around said inner conduit.

3. The apparatus of Claim 2 wherein said "V"-shaped grooves comprise first and second walls which are disposed at an angle of between 10° and 15° with respect to an axis perpendicular to an outer surface of said sheet of compressible insulating material.

4. The apparatus of Claim 1 wherein said compressible insulating material is formed with mineral wool, urethane foam, foam glass, fibreglass or calcium silicate.

5. An insulated pipe apparatus comprising:
means for forming an inner substantially cylindrical conduit for carrying fluids;
means for forming a single sheet of compressible insulating material in approximately trapezoidal sections wherein said trapezoidal sections are wrapped around said inner conduit so that said insulating material extends substantially the length of said inner conduit to form a circumferentially and longitudinally contiguous sleeve along the length of said inner conduit;
means for forming a rigid circumferentially contiguous sheet of corrugated material around said compressible insulated material to form a circumferentially and longitudinally contiguous sleeve along the length of said insulating material;
means for forming a rigid outer casing resistant to mechanical stress and moisture ingress, coaxial and coextensive with said inner conduit and surrounding said compressible insulating material;
means for sealing the ends of said insulated pipe apparatus between the outer surface of said inner conduit and said rigid outer casing; and means for connecting said inner conduit to external equipment.

6. An insulated pipe apparatus, comprising:
an inner substantially cylindrical conduit for carrying fluids;
compressible insulating material surrounding said inner conduit and extending substantially the length of said inner conduit, said compressible insulating material being formed of a sheet of approximately trapezoidal sections defined by "V"-shaped grooves which when wrapped around said inner conduit form a circumferentially and longitudinally contiguous sleeve along the length of said inner conduit;
a rigid outer casing resistant to mechanical stress and moisture ingress, coaxial and coextensive with said inner conduit and surrounding said compressible insulating material;
means defining a plurality of longitudinal elongated voids between said outer casing and said compressible insulating material, said elongated voids being of substantially constant cross-section and coextensive with said compressible insulating material;
interconnecting means for interconnecting said elongated voids and sealing the ends of said insulated pipe apparatus between the outer surface of said inner conduit and said rigid outer casing;
and coupling means for connecting said inner conduit to external equipment.

7. A method of constructing an insulated pipe apparatus, said method comprising the steps of:
forming a substantially cylindrical inner conduit for carrying fluids;
forming a single sheet of compressible insulating material in approximately trapezoidal sections;
wrapping said insulating material around said inner conduit so that said insulating material extends substantially the length of said inner conduit to form a circumferentially and longitudinally contiguous sleeve along the length of said inner conduit;
forming a rigid outer casing resistant to mechanical stress and moisture ingress, coaxial and coextensive with said inner conduit and surrounding said insulating material; and sealing the ends of said insulated pipe apparatus between the outer surface of said inner conduit and said rigid outer casing.

8. The method of Claim 7 further including the step of forming a rigid circumferentially contiguous sheet of corrugated material around said compressible insulated material to form a circumferentially and longitudinally contiguous sleeve along the length of said compressible insulating material.