CA1091901A - Chemical resistant process equipment and method of producing process equipment - Google Patents
Chemical resistant process equipment and method of producing process equipmentInfo
- Publication number
- CA1091901A CA1091901A CA257,372A CA257372A CA1091901A CA 1091901 A CA1091901 A CA 1091901A CA 257372 A CA257372 A CA 257372A CA 1091901 A CA1091901 A CA 1091901A
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- Canada
- Prior art keywords
- resin
- chemical
- fiber
- recited
- fabric
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Reinforced Plastic Materials (AREA)
Abstract
Chemical-resistant fiberglass reinforced plastic process equipment enclosing an open area is produced by helical winding, centrifugal casting, or the like. The equipment includes a primary corrosion barrier formed by an inner surface of resin with a reinforcing fabric, an interior layer, and an exterior layer. The reinforcing fabric comprises a chemical-resistant polyester non-woven surfacing fabric having interlocked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 0.5, the values being determined in the absence of a binder. This non-woven fabric may also be used as the interior layer, both with a conventional inner surface or non-woven fabric backed inner surface, or as an overwind for the exterior layer.
Description
~9~o~
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to reinforced-polyester, vinyl ester, or epoxy chemical-resistant process equipment, and methods of producing such equipment. For many appli-cations, such as chemical processing, petroleum production and refining, pulp and paper mills, etc., fiberglass reinforced plastics pipe, tanks, vessels, etc., have found widespread use because of their chemical-resis-tance, abrasion-resistance, and strength. Detailed specifications for such structures are given in U.S. Department of Commerce Standard PS 15-69 "Custom Contact-Molded Reinforced Polyester Chemical Resistant Process Equipment". The conventional construction consists of an inner surface and an interior layer, the inner surface and interior layer together forming a chemical resistant barrier, and an exterior layer providing strength. The inner layer consists of a resin suitable for use in the environment for which it is intended to be used reinforced by (impregnated in) a reinforcing surfacing material.
Section 3.2.4 of PS 15-6g calls for the surfacing material to be a commercial grade chemical-resistant glass having a coupling agent (C-glass), and conventionally this is what is universally used as the surfacing material. Other surfacing materials have been suggested as a replacement for C-glass, such as -the material known under the trade mark PELLON ~see U.S. patent No. 3,501,359) which is an adhesive bonded non-woven fabric; however none have previously been found to demonstrate overall superiority to C-glass for this use.
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to reinforced-polyester, vinyl ester, or epoxy chemical-resistant process equipment, and methods of producing such equipment. For many appli-cations, such as chemical processing, petroleum production and refining, pulp and paper mills, etc., fiberglass reinforced plastics pipe, tanks, vessels, etc., have found widespread use because of their chemical-resis-tance, abrasion-resistance, and strength. Detailed specifications for such structures are given in U.S. Department of Commerce Standard PS 15-69 "Custom Contact-Molded Reinforced Polyester Chemical Resistant Process Equipment". The conventional construction consists of an inner surface and an interior layer, the inner surface and interior layer together forming a chemical resistant barrier, and an exterior layer providing strength. The inner layer consists of a resin suitable for use in the environment for which it is intended to be used reinforced by (impregnated in) a reinforcing surfacing material.
Section 3.2.4 of PS 15-6g calls for the surfacing material to be a commercial grade chemical-resistant glass having a coupling agent (C-glass), and conventionally this is what is universally used as the surfacing material. Other surfacing materials have been suggested as a replacement for C-glass, such as -the material known under the trade mark PELLON ~see U.S. patent No. 3,501,359) which is an adhesive bonded non-woven fabric; however none have previously been found to demonstrate overall superiority to C-glass for this use.
- 2 -~LQ~19~
According to the present invention, a substitute is provided for C-glass surfacing material Eor the inner surface of chemical resistant process equipment that has overall superiority thereto. According to the present invention the resin of the inner surface is reinforced by (impregnated in) a chemical-resistant polyester non-woven fabric having inter-locked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 0.5 ~the values determined in the absence of a binder), said fabric being known under the trade mark NEXUS, and disclosed fully in U.S. patent No. 3,485,706.
Preferably, the NEXUS surfacing fabric used is produced from a continuous or staple polyester fabric known under the trade mark DACRON Type 106 and manufactured by E.I. DuP~nt de Nemours & Co., and described in Dacron Polyester Fiber Bulletin D-235 "The Chemical Resistance of Dacron". Other suitable chemical-resistant polyester staples may also be employed. The NEXUS surfacing fabric is preferably of style 0012 and 1012, although other styles are also suitable~
In many modern applications utilizing modern resins, elongation can and does occur. Resin elongation can be 4-7%.
C-glass cannot adapt to such elongations and still perform its desired functions properly, whereas NEXUS surfacing fabric can, while being ~ust as suitable as C-glass when there is less elongation. When NEXUS surfacing fabric is used as a ~1~)9~
replacement for C-glass as the reinforcing fabric for the inner surface of process equipment such as pipes, tanks, etc., the end product has the following advant~ges over an otherwise identical product using C-glass as the inner surface re-inforciny material: (1) Superior wet abrasion resistance,(2) Superior impact resistance, (3) Improved resistance to cyclic stressiny, and (4) Increased service life. For instance, under ASTM Test Method D-2143-69 (Standard Method of Test for Cyclic Pressure Strenyth of Reinforced Thermosettiny Plastic Pipe), pipe specimens with Nexus reinforced liners exceeded 750,000 cycles without failure compared with approxi-mately 120,000 cycles for pipe specimens having C-glass reinforced liners.
In addition to being useful for the reinforcing fabric for the inner layer of processing equipment, Nexus fabric has also been found to be useful for the equipment interior layer as a "tie-down" of C-glass surfacing mat (forming the inner surface) in filament wound pipe, tanks, and other cylindrical structures. Nexus surfacing fabric has good resin absorbency, tensile strength, and controlled elongation characteristics that provide for tie-down of the C-glass mat over flanges and other areas having contours of relatively short radii, and can result in a substantial reduction of voids and pits now common in the inner surface of filament wound fiberglass reinforced plastic structures haviny short radii changes in section. Other materials (see U.S. Patent No. 3,676,246), such as Pellon, have been suggested for such a ~0919~
tie-down use, however none have been found to be as suitable as Nexus surfacing fabric for this use.
Extra windings of Nexus may also be used as the interior layer of the process equipment, or Nexus may be used as an overwind for the exterior layer in situations where the exterior of the process equipment is subjected to chemical attack.
According to the present invention, improvecl process equipment can be produced according to various methods such as helical winding, centrifugal casting, continuous pultrusion, and continuous laminating. Helical winding is especially applicable when the process equipment to be formed is pipe, cylindrical tanks, etc.
It is the primary object of the present invention to provide an improved product and method of producing same for use as chemical resistant processing equipment. This and other objects of the invention will become clear from an inspection of the detailed description of the drawings and from the appended claims.
BRIEF DESCRIPTION OF T~E DRAWINGS
FIGURE l is a cross-sectional view of a pipe constructed according to the present invention;
FIGURE 2 is a cross-sectional view of an alternative embodiment of a pipe according to the present invention;
FIGURE 3 is a schematic view of apparatus for producing a pipe according to a method of the present invention; and ~L09~
FIGURE 4 is a schematic view of an alternative embodiment of apparatus for producing pipe according to an alternative method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
A piece of reinforced-polyester, vinyl ester, or epoxy chemical-resistant process eguipment, a pipe 10, according to the present invention is shown in FIGURE 1. The pipe 10 consists of a primary corrosion barrier 12 and strength layers and a secondary corrosion barrier in the form of exterior layer 13. The primary corrosion barrier 12 consists of an inner surface 14 and an interior layer 15. The inner surface 14 consists of a chemical-resistant polyester non-woven surfacing fabric having interlocked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 0.5 ~the values determined in the absence of a binder) and a resin~
The inner surface 14 defines an open area 16. This fabric is commonly referred to as NEXUS, and is disclosed fully in U.S. patent No. 3,4~5,706. The NEXUS surfacing fabric preferably is style 0012 or 1012, and is produced from DACRON type 106 polyester staple, or other chemical resistant polyester staple. The NEXUS surfacing fabric is impregnated with resin, and a resin-rich inner portion of the inner surface is formed. Polyester resin, vinyl-ester resin, epoxy resin, or other resins that have good chemical ~915~
and abrasion resistant properties may be used with the NEXUS
surfacing fabric reinforcement. The resin wi]l be chosen dependent upon what environment the process equipment will be used in. One particular polyester resin well suited for general use is an unsaturated liquid polyester vinyl ester resin known under the trademark ATLAC 382 and manufactured by ICI United States Inc., while DERAKANE 411-45 (trademark) a liquid unsaturated vinyl ester resin, and D.E.R.-331 (trademark), a liquid epoxy-resin both manufactured by Dow Chemical Co., are suitable exemplary vinyl ester and epoxy resins respectively.
Surrounding the inner surface 14 is an interior layer 15, which also forms part of the primary corrosion barrier 12. The interior layer 15 may be, and conventionally is, continuous chopped glass fiber strand with a high resin content. However, it has been found that with NEXUS surfacing fabric as the inner surface reinforcement material, no interior layer is needed if the inner surface is thick enough, consisting of one or more windings of NEXUS, producing a corrosion barrier up to 50 mils thick. In such a case, NEXUS
itself ~resin-impregnated) may be considered the interior layer.
The exterior layer 13 is preferably formed by successive windings of fiberglass roving, mat, or the like.
Any suitable glass roving or mat may be selected, and wound to any desired thickness depending upon the environment in which it is to be used (chemical corrosiveness thereof), and the strength desired. Alternate layers of woven glass roving or cloth and chopped-strand glass may be used. Enough resin should be present to prevent fiber show. A typical overwind fiberglass for forming the exterior layer or portions thereof is a continuous strand E glass roving known under the trademark Owens-Corning Fiberglass Type 30, with the resin system the same as used in the inner surface.
An alternative embodiment of a piece of reinforced-polyester, vinyl ester or epoxy chemical resistant process equipment, a pipe 20, according to the present invention is shown in FIGURE 2. The pipe 20 consists of a primary corrosion barrier 21 and strength layers and secondary corrosion barrier 26. The primary corrosion barrier 21 consists of an inner surace 22 of conventional chemical resistant glass surfacing mat rein~orcing a resin, and an interior layer overwind 2 therefor. The overwind 2~ is of NEXUS surfacing fabric, having good resin absorbency, tensile strength and controlled elongation characteristics, and is effective for tieing down C-glass surfacing mat 22, over flanges and other areas having contours of relatively short radii. The exterior layer 26 can be of the same conventional materials as shown in the FIGURE 1 embodiment.
It is to be understood that other layers may also be provided for process equipment according to the present invention, according to conventional practice. For instance, if the exterior of the process equipment is to be exposed to a corrosive environment, a corrosion barrier may be formed over the exterior 13 (or 26). Such exterior layer could be .~P'~
~9Q~
chopped-strand glass with a resin-rich outer surface, such as resin-impregnated Nexus surfacing fabric (the same as de-scribed with respect to inner surface 14). Other types of exterior surfaces also may be formed.
Process equipment formed according to the present invention has the following improved properties over process equipment formed from otherwise similar materials only with a C-glass reinforcing mat instead of Nexus surfacing fabric re-inforcing mat for the resin-rich inner surface: tl) Superior wet abrasion resistance, (2) Superior impact resistance,
According to the present invention, a substitute is provided for C-glass surfacing material Eor the inner surface of chemical resistant process equipment that has overall superiority thereto. According to the present invention the resin of the inner surface is reinforced by (impregnated in) a chemical-resistant polyester non-woven fabric having inter-locked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 0.5 ~the values determined in the absence of a binder), said fabric being known under the trade mark NEXUS, and disclosed fully in U.S. patent No. 3,485,706.
Preferably, the NEXUS surfacing fabric used is produced from a continuous or staple polyester fabric known under the trade mark DACRON Type 106 and manufactured by E.I. DuP~nt de Nemours & Co., and described in Dacron Polyester Fiber Bulletin D-235 "The Chemical Resistance of Dacron". Other suitable chemical-resistant polyester staples may also be employed. The NEXUS surfacing fabric is preferably of style 0012 and 1012, although other styles are also suitable~
In many modern applications utilizing modern resins, elongation can and does occur. Resin elongation can be 4-7%.
C-glass cannot adapt to such elongations and still perform its desired functions properly, whereas NEXUS surfacing fabric can, while being ~ust as suitable as C-glass when there is less elongation. When NEXUS surfacing fabric is used as a ~1~)9~
replacement for C-glass as the reinforcing fabric for the inner surface of process equipment such as pipes, tanks, etc., the end product has the following advant~ges over an otherwise identical product using C-glass as the inner surface re-inforciny material: (1) Superior wet abrasion resistance,(2) Superior impact resistance, (3) Improved resistance to cyclic stressiny, and (4) Increased service life. For instance, under ASTM Test Method D-2143-69 (Standard Method of Test for Cyclic Pressure Strenyth of Reinforced Thermosettiny Plastic Pipe), pipe specimens with Nexus reinforced liners exceeded 750,000 cycles without failure compared with approxi-mately 120,000 cycles for pipe specimens having C-glass reinforced liners.
In addition to being useful for the reinforcing fabric for the inner layer of processing equipment, Nexus fabric has also been found to be useful for the equipment interior layer as a "tie-down" of C-glass surfacing mat (forming the inner surface) in filament wound pipe, tanks, and other cylindrical structures. Nexus surfacing fabric has good resin absorbency, tensile strength, and controlled elongation characteristics that provide for tie-down of the C-glass mat over flanges and other areas having contours of relatively short radii, and can result in a substantial reduction of voids and pits now common in the inner surface of filament wound fiberglass reinforced plastic structures haviny short radii changes in section. Other materials (see U.S. Patent No. 3,676,246), such as Pellon, have been suggested for such a ~0919~
tie-down use, however none have been found to be as suitable as Nexus surfacing fabric for this use.
Extra windings of Nexus may also be used as the interior layer of the process equipment, or Nexus may be used as an overwind for the exterior layer in situations where the exterior of the process equipment is subjected to chemical attack.
According to the present invention, improvecl process equipment can be produced according to various methods such as helical winding, centrifugal casting, continuous pultrusion, and continuous laminating. Helical winding is especially applicable when the process equipment to be formed is pipe, cylindrical tanks, etc.
It is the primary object of the present invention to provide an improved product and method of producing same for use as chemical resistant processing equipment. This and other objects of the invention will become clear from an inspection of the detailed description of the drawings and from the appended claims.
BRIEF DESCRIPTION OF T~E DRAWINGS
FIGURE l is a cross-sectional view of a pipe constructed according to the present invention;
FIGURE 2 is a cross-sectional view of an alternative embodiment of a pipe according to the present invention;
FIGURE 3 is a schematic view of apparatus for producing a pipe according to a method of the present invention; and ~L09~
FIGURE 4 is a schematic view of an alternative embodiment of apparatus for producing pipe according to an alternative method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
A piece of reinforced-polyester, vinyl ester, or epoxy chemical-resistant process eguipment, a pipe 10, according to the present invention is shown in FIGURE 1. The pipe 10 consists of a primary corrosion barrier 12 and strength layers and a secondary corrosion barrier in the form of exterior layer 13. The primary corrosion barrier 12 consists of an inner surface 14 and an interior layer 15. The inner surface 14 consists of a chemical-resistant polyester non-woven surfacing fabric having interlocked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 0.5 ~the values determined in the absence of a binder) and a resin~
The inner surface 14 defines an open area 16. This fabric is commonly referred to as NEXUS, and is disclosed fully in U.S. patent No. 3,4~5,706. The NEXUS surfacing fabric preferably is style 0012 or 1012, and is produced from DACRON type 106 polyester staple, or other chemical resistant polyester staple. The NEXUS surfacing fabric is impregnated with resin, and a resin-rich inner portion of the inner surface is formed. Polyester resin, vinyl-ester resin, epoxy resin, or other resins that have good chemical ~915~
and abrasion resistant properties may be used with the NEXUS
surfacing fabric reinforcement. The resin wi]l be chosen dependent upon what environment the process equipment will be used in. One particular polyester resin well suited for general use is an unsaturated liquid polyester vinyl ester resin known under the trademark ATLAC 382 and manufactured by ICI United States Inc., while DERAKANE 411-45 (trademark) a liquid unsaturated vinyl ester resin, and D.E.R.-331 (trademark), a liquid epoxy-resin both manufactured by Dow Chemical Co., are suitable exemplary vinyl ester and epoxy resins respectively.
Surrounding the inner surface 14 is an interior layer 15, which also forms part of the primary corrosion barrier 12. The interior layer 15 may be, and conventionally is, continuous chopped glass fiber strand with a high resin content. However, it has been found that with NEXUS surfacing fabric as the inner surface reinforcement material, no interior layer is needed if the inner surface is thick enough, consisting of one or more windings of NEXUS, producing a corrosion barrier up to 50 mils thick. In such a case, NEXUS
itself ~resin-impregnated) may be considered the interior layer.
The exterior layer 13 is preferably formed by successive windings of fiberglass roving, mat, or the like.
Any suitable glass roving or mat may be selected, and wound to any desired thickness depending upon the environment in which it is to be used (chemical corrosiveness thereof), and the strength desired. Alternate layers of woven glass roving or cloth and chopped-strand glass may be used. Enough resin should be present to prevent fiber show. A typical overwind fiberglass for forming the exterior layer or portions thereof is a continuous strand E glass roving known under the trademark Owens-Corning Fiberglass Type 30, with the resin system the same as used in the inner surface.
An alternative embodiment of a piece of reinforced-polyester, vinyl ester or epoxy chemical resistant process equipment, a pipe 20, according to the present invention is shown in FIGURE 2. The pipe 20 consists of a primary corrosion barrier 21 and strength layers and secondary corrosion barrier 26. The primary corrosion barrier 21 consists of an inner surace 22 of conventional chemical resistant glass surfacing mat rein~orcing a resin, and an interior layer overwind 2 therefor. The overwind 2~ is of NEXUS surfacing fabric, having good resin absorbency, tensile strength and controlled elongation characteristics, and is effective for tieing down C-glass surfacing mat 22, over flanges and other areas having contours of relatively short radii. The exterior layer 26 can be of the same conventional materials as shown in the FIGURE 1 embodiment.
It is to be understood that other layers may also be provided for process equipment according to the present invention, according to conventional practice. For instance, if the exterior of the process equipment is to be exposed to a corrosive environment, a corrosion barrier may be formed over the exterior 13 (or 26). Such exterior layer could be .~P'~
~9Q~
chopped-strand glass with a resin-rich outer surface, such as resin-impregnated Nexus surfacing fabric (the same as de-scribed with respect to inner surface 14). Other types of exterior surfaces also may be formed.
Process equipment formed according to the present invention has the following improved properties over process equipment formed from otherwise similar materials only with a C-glass reinforcing mat instead of Nexus surfacing fabric re-inforcing mat for the resin-rich inner surface: tl) Superior wet abrasion resistance, (2) Superior impact resistance,
(3) Improved resistance to cyclical stress, and (~) Increased service life.
Processing equipment according to the present invention may be formed by any suitable process that achieves the desired product. Exemplary conventional processes that may be used - depending on the product to be produced -include contact molding (by hand lay-up, spray-up, vacuum bag, pressure-bag, or autoclave), matched molding ~by compression molding, injection molding, or pressure-bag molding), en-capsulation, rotational molding, and especially filamentwinding, helical winding, continuous pultrusion, continuous laminating, and centrifugal casting. Helical winding may be practiced utilizing the apparatus shown in FIGURE 3 to form chemical-resistant polyester pipe or vinyl ester and epoxy resin articles or pipe. Resin is coated on a mandrel 30 and/or resin from a bath 32 is impregnated on a strip of Nexus surfacing fabric 33 passing therethrough. The strip 33 is then helically wound around the mandrel 30 as the mandrel rotates, and after a section is completed the resin is cured, thereby forming the inner surface for the pipe. Other windings of Nexus surfacing fabric may also be app:Lied, as may 9~
chopped-strand glass reinforcing mat or the like. The exterior layers may also be applied by successive wrappings around the mandrel. The interior layer may be applied prior to curing of the resin of the inner surface or after it, depending upon the particular materials involved, and the exterior layers may be applied before or after curing of the interior layer depending upon the materials involved. Curing of resins in the inner surface and interior layer may be simultaneous.
FIGURE 4 shows formation of the inner layer of a pipe according to the present invention by centri~ugal casting. Nexus reinforcing fabric 39 is disposed along the interior o~ the tubular rotatable mold member 40. Resin 41 is applied by resin~applicator 42 as the mold member rotates.
Since the reinforcing fabric 39 is denser than the resin 41, a pipe having a very resin-rich interior surface is formed. The mandrel 40 may be steam heated while rotating to effect resin cure.
While the invention has been herein shown and described in what is presently conceived to be the most practical and preferred embodiment, it will be obvious to one of ordinary skill in the art that many modifications may be made thereof within the scope of the invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent structures and methods.
Processing equipment according to the present invention may be formed by any suitable process that achieves the desired product. Exemplary conventional processes that may be used - depending on the product to be produced -include contact molding (by hand lay-up, spray-up, vacuum bag, pressure-bag, or autoclave), matched molding ~by compression molding, injection molding, or pressure-bag molding), en-capsulation, rotational molding, and especially filamentwinding, helical winding, continuous pultrusion, continuous laminating, and centrifugal casting. Helical winding may be practiced utilizing the apparatus shown in FIGURE 3 to form chemical-resistant polyester pipe or vinyl ester and epoxy resin articles or pipe. Resin is coated on a mandrel 30 and/or resin from a bath 32 is impregnated on a strip of Nexus surfacing fabric 33 passing therethrough. The strip 33 is then helically wound around the mandrel 30 as the mandrel rotates, and after a section is completed the resin is cured, thereby forming the inner surface for the pipe. Other windings of Nexus surfacing fabric may also be app:Lied, as may 9~
chopped-strand glass reinforcing mat or the like. The exterior layers may also be applied by successive wrappings around the mandrel. The interior layer may be applied prior to curing of the resin of the inner surface or after it, depending upon the particular materials involved, and the exterior layers may be applied before or after curing of the interior layer depending upon the materials involved. Curing of resins in the inner surface and interior layer may be simultaneous.
FIGURE 4 shows formation of the inner layer of a pipe according to the present invention by centri~ugal casting. Nexus reinforcing fabric 39 is disposed along the interior o~ the tubular rotatable mold member 40. Resin 41 is applied by resin~applicator 42 as the mold member rotates.
Since the reinforcing fabric 39 is denser than the resin 41, a pipe having a very resin-rich interior surface is formed. The mandrel 40 may be steam heated while rotating to effect resin cure.
While the invention has been herein shown and described in what is presently conceived to be the most practical and preferred embodiment, it will be obvious to one of ordinary skill in the art that many modifications may be made thereof within the scope of the invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent structures and methods.
Claims (2)
1. A piece of reinforced chemical-resistant process equipment enclosing an open area, comprising a) an inner chemical resistant surface defining said open area, said inner surface including (i) a resin, and (ii) a reinforcing fabric impregnated by said resin, said reinforcing fabric comprising a chemical-resistant polyester non-woven surfacing fabric having interlocked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement complete-ness of at least 0.5, said values being determined in the absence of a binder, b) an interior layer of supporting chemical-resistant material surrounding said inner surface, and c) an exterior layer of strengthening material surrounding said interior layer.
2. A piece of process equipment as recited in Claim 1 wherein said interior layer comprises a chemical-resistant polyester resin-impregnated non-woven fabric having interlocked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement complete-ness of at least 0.5, said values being determined in the absence of a binder.
3. A piece of process equipment as recited in Claim 1 further comprising an overwind for said exterior layer, said overwind comprising a chemical-resistant polyester non-woven resin-impregnated fabric having interlocked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 0.5, said values being determined in the absence of a binder.
4. A piece of process equipment as recited in Claim 1 wherein said exterior layer comprises layers of resin-impregnated continuous roving, woven roving or cloth or chopped glass fiber strand or mat.
5. A method for producing a piece of reinforced chemical-resistant process equipment enclosing an open area, said method comprising the steps of a) forming a chemical resistant resin-rich inner surface of said piece of equipment defining said open area by impregnating with resin a reinforcing chemical-resistant polyester non-woven fabric having interlocked fibers charac-terized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 0.5, said values being determined in the absence of a binder, b) forming an interior layer of supporting chemical-resistant material surrounding said inner surface, c) forming an exterior layer of strengthening material surrounding said interior layer, and d) curing the resin in the inner surface.
6. A method as recited in Claim 5, wherein said interior layer comprises a resin-impregnated material, and wherein said step of curing the resin in the inner surface is accomplished after formation of said interior layer, simultaneously with the curing of the resin in said interior layer, and before forming said exterior layer.
7. A method as recited in Claim 5, wherein said step of forming said inner surface is accomplished by helical winding or a resin-impregnated continuous web of said non-woven fabric on a mandrel.
8. A method as recited in Claim 7, wherein said mandrel is resin coated prior to helical winding of said non-woven fabric thereon.
9. A method as recited in Claim 5, wherein said step of forming said inner surface is accomplished by centrifugal casting.
10. A method as recited in Claim 5, wherein said piece of equipment is a tubular member and wherein said step of forming an interior layer is accomplished by helically wrapping a continuous web of chemical-resistant polyester non-woven fabric having interlocked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 005, said values being determined in the absence of a binder, around said inner surface.
11. A method as recited in Claim 10, wherein said step of forming said exterior layer is accomplished by helically winding continuous roving, woven roving or chopped glass strand or mat around said interior layer.
12. A method as recited in Claim 5, comprising the further steps of overwinding said exterior layer with a chemical-resistant polyester non-woven resin-impregnated fabric having interlocked fibers characterized by a fiber-interlock value due to fiber entanglement of at least 7 with a fiber entanglement completeness of at least 0.5, said values being determined in the absence of a binder, and curing said resin in said non-woven fabric overwind.
13. A method as recited in Claim 5, wherein said inner surface resin is selected from the group consisting of polyester, vinyl ester, and epoxy resins.
The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:
1. A charge for use in graphitization furnaces, compo-sed of 85 to 95 percent by mass of coke with not less than 90 percent by volume of size fraction 0.5 to 2 mm and not more than 10 percent by volume of size fraction 2 to 10 mm and of 5 to 15 percent by mass of sawdust.
2. A charge having reducing properties and composed of 85 to 95 percent by mass of coke with not less than 90 percent by volume of size fraction 0.5 to 2 mm and not more than 10 percent by volume of size fraction 2 to 10 mm and of 5 to 15 percent by mass of sawdust thermally processed at a temperature of not less than 2000°C in the course of graphitization.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US61356175A | 1975-09-15 | 1975-09-15 | |
| US613,561 | 1975-09-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1091901A true CA1091901A (en) | 1980-12-23 |
Family
ID=24457781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA257,372A Expired CA1091901A (en) | 1975-09-15 | 1976-07-20 | Chemical resistant process equipment and method of producing process equipment |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1091901A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4876124A (en) * | 1986-10-03 | 1989-10-24 | Owens-Corning Fiberglas Corporation | Underground tank |
-
1976
- 1976-07-20 CA CA257,372A patent/CA1091901A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4876124A (en) * | 1986-10-03 | 1989-10-24 | Owens-Corning Fiberglas Corporation | Underground tank |
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