CA2162357A1 - Method and apparatus for lining manhole assemblies and the like - Google Patents
Method and apparatus for lining manhole assemblies and the likeInfo
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- CA2162357A1 CA2162357A1 CA 2162357 CA2162357A CA2162357A1 CA 2162357 A1 CA2162357 A1 CA 2162357A1 CA 2162357 CA2162357 CA 2162357 CA 2162357 A CA2162357 A CA 2162357A CA 2162357 A1 CA2162357 A1 CA 2162357A1
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- liner
- gasket
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- section
- cast
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Abstract
Each section of a manhole assembly is cast in a mold which incorporates a mesh-like wire cage superstructure, employed to enhance the structural strength of the cast member, and liner sections joined end to end about the interior of the cast member by a slide-on clip structure which locks flanges of adjacent liner sections and compresses a gasket therebetween to assure a liquid-tight interior. The liner sections are produced from a low density polyethylene material using a rotocasting method capable of forming sturdy reenforcement ribs providing superior structural strength to maintain and retain the shape of the liner sections. Ties are passed through openings provided in the reenforcement ribs and looped around the members of the wire reenforcement cage structure to assure proper alignment of the liner sections as well as permanent anchoring of the liner sections to the cast material. Mounting mandrels are employed during the casting operation to maintaining proper positioning of a gasket and the liner sections and to retain the gasket in proper position within the hole defined by the mandrel.
The liner material in inert to corrosive forces.
Top liner and manhole extension members, also formed utilizing the rotocast method, protect the upper regions of the manhole assembly. The extension member cooperates with the top liner to provide a height adjustable water-tight seal for cast material between the top liner and grade level.
The liner material in inert to corrosive forces.
Top liner and manhole extension members, also formed utilizing the rotocast method, protect the upper regions of the manhole assembly. The extension member cooperates with the top liner to provide a height adjustable water-tight seal for cast material between the top liner and grade level.
Description
The present invention relates to manhole assemblies and more particularly a novel method and apparatus for forming manhole assemblies utilizing liner sections formed of a suitable material which is inert to the toxlc influences encountered in manhole assemblies to provide a manhole assembly having an interior liner exhibiting superior water-tight capabilities to protect the cast material.
It is well known to those responsible for the design, construction, maintenance and use of waste water handling and treatment systems that the cumulative effect of toxic materials and/or chemicals carried by waste water cause interior corrosion and deterioration of the cast material, which harmful effects are cumulative and lead to a significant reduction in the useful operating life of such systems resulting in premature and costly repair and/or replacement of such systems and/or components thereof.
Some of the more significant corrosive influences experienced by cast manhole assemblies and solutions and techniques for substantially reducing such corrosive effects are set forth in detail in U.S. Patent No. 4,751,799 issued June 21, 1988 and U.S. Patent No. 5,081,802 issued January 21, 1992, both of which are assigned to the assignee of the present application Briefly, the techniques employed therein to shield the cast material from corrosion and/or deterioration include the provision of a liner formed of a plurality of vacuum formed liner sections joined together to provide a water-tight protective shield for the cast material.
Although the techniques and apparatus set forth in the above-mentioned patents have considerably reduced deterioration of cast members due to corrosive influences carried by effluent handled by the cast members, the present inventors have nevertheless noted a number of disadvantages of prior art techniques which include, among others, the following:
1. Liner sectlons produced using vacuum forming techniques having a high scrap rate.
2. The vacuum forming process limits the panel size which can be formed making it necessary to increase the number of panels needed to form a cylinder.
It is well known to those responsible for the design, construction, maintenance and use of waste water handling and treatment systems that the cumulative effect of toxic materials and/or chemicals carried by waste water cause interior corrosion and deterioration of the cast material, which harmful effects are cumulative and lead to a significant reduction in the useful operating life of such systems resulting in premature and costly repair and/or replacement of such systems and/or components thereof.
Some of the more significant corrosive influences experienced by cast manhole assemblies and solutions and techniques for substantially reducing such corrosive effects are set forth in detail in U.S. Patent No. 4,751,799 issued June 21, 1988 and U.S. Patent No. 5,081,802 issued January 21, 1992, both of which are assigned to the assignee of the present application Briefly, the techniques employed therein to shield the cast material from corrosion and/or deterioration include the provision of a liner formed of a plurality of vacuum formed liner sections joined together to provide a water-tight protective shield for the cast material.
Although the techniques and apparatus set forth in the above-mentioned patents have considerably reduced deterioration of cast members due to corrosive influences carried by effluent handled by the cast members, the present inventors have nevertheless noted a number of disadvantages of prior art techniques which include, among others, the following:
1. Liner sectlons produced using vacuum forming techniques having a high scrap rate.
2. The vacuum forming process limits the panel size which can be formed making it necessary to increase the number of panels needed to form a cylinder.
3. Panels produced using the vacuum forming process have variations in wall thickness and require mechanical fasteners which are tedious and time consuming to mount and assemble.
4. Vacuum formed liners are degraded by stream curing operations employed during the casting process and further do not hold up well in environments experiencing frigid temperatures.
The present invention is characterized by comprising a method and apparatus for resolving the disadvantages of present day design including among them those discussed hereinabove, as well as - delivering significant improvements in manufacturing, assembly and casting as well as field installation and performance of the entire system.
5The present invention is characterized by utilizing a rotocasting process for molding panels, preferably from polyethylene, through the use of a tool fabricated to resemble an elliptical cylinder utilized to form two panels simultaneously. In one 10preferred embodiment, each panel represents one-third of the desired circumference of a cylindrical shaped cast member.
Tooling requirements are minimized by utilization of a tool having a standard length 15determined by the diameter of the cast member and having reenforcing ribs equally spaced along the height of the tool by a predetermined distance enabling panels to be cut down to a desired shorter height.
20The tool utilized to cast the liner sections and containing the mold material is spun by suitable drive means to simultaneously form a pair of rotocast liner members having substantially solid flanges, reenforcing ribs and joining ribs which act 25to provide curved liner sections having excellent structural strength to prevent warping and buckling and which are joined by suitable plastic ties to the internal wire mesh of the cast member, thereby providing excellent anchoring of the liner sections 30to the cast material. This arrangement provides an anchoring arrangement which has a significantly improved capability of being properly centered and retaining its curved shape without buckling, bending or warping as compared with the roto-cast liners disclosed in U. S. Patent No. 5,303,518, issued April 19, 1994.
The liner sections, preparatory to placement within the casting mold, are joined to one another by a clip which slides over a pair of returns or flanges of adjacent liner sections, locking the returns to one another and squeezing a resilient compressible foam rubber strip positioned between adjacent surfaces of the joined returns which assures a water-tight seam therebetween. The clip also serves as a fluid barrier over the entire length of the seam.
The clip member joining vertical returns of adjacent liner sections may be either a plastic clip assembly or a stainless clip assembly, the latter being capable of either being slipped or snap-fitted into position.
The liner and plastic clip are preferably formed of polyethylene which inert to substantially all of the toxic materials encountered in sewage systems yielding excellent protection for the cast material. In addition, polyethylene prevent leaching.
Gasketing is provided between vertically stacked sections of the manhole assembly to provide a water-tight seal between the manhole base and riser sections and between the riser section (or sections) and the top section. Flanges are provided on the liners at the upper ends thereof to provide corrosive protection along the interior region of the joined manhole sections.
Openings are formed in the liner section at those Locations designated for receipt of a conduit. A connector mandrel arranged within the mold preparatory to casting supports a gasket for water-tightly sealing a conduit or pipe inserted into the manhole assembly, the gasket being provided with a continuous outer flange having a substantially T-shaped cross-section for anchoring the gasket in the cast material. The main body portion of the gasket is provided with a plurality of continuous annular voids of varying lengths which are diagonally oriented to control the resiliency and compression of the gasket during the insertion of conduit thereby assuring placement of the gasket material where it is needed most for supporting and water-tightly sealing a conduit inserted therein.
A top liner member is provided for protecting the roof of the manhole assembly. The substantially circular-shaped top liner is provided with reenforcing ribs and a substantially stepped cylindrical projection defining an eccentric opening in the top liner. The reenforcing ribs of the slab top liner are joined to a wire reenforcement embedded in the cast member by non-corrosive tie members. The generally cylindrical-shaped access opening portion of the liner is integral with the disk-shaped portion and cooperates with a hollow, cylindrical-shaped extension member telescopically received within the stepped, cylindrical-shaped projection extending upwardly from the top liner.
One or more O-rings are arranged in seating recesses arranged about the outer periphery of the cylindrical extension member to provide an adjustable, water-tight seal between the telescoping members.
The sealants employed between adjacent vertically aligned sections of the manhole assembly may be EPDM which are employed in waste-water applications and nitrile gaskets for use in .
applications in which oil and fluorocarbon materials are encountered.
5It is therefore one object of the present invention to provide precast concrete vertical placed structures, manhole assemblies or the like having novel rotocast liner assemblies impervious to toxic materials for protecting the concrete.
10Still another object of the present invention is to provide a novel liner assembly for lining and protecting annular concrete structures and the like from corrosion, the liner assembly being formed of liner sections having integral 15returns joined to one another by fastening clips, eliminating the need for conventional fasteners and having resilient gasket means arranged between adjacent surfaces of the returns for providing an excellent water-tight seal along the clip assembly.
20Another object of the present invention is to provide novel liner sections joined to one another with slide-on clip means and having reenforcing ribs which are anchored to the cast concrete by means of ties permanently anchoring the 25liners to the wire mesh reenforcement of the cast member to assure retention of the liner section curvilinear-shape and to present bulging or warping.
Still another object of the present lnvention is to provide a liner assembly for lining 30manholes and the like and which is easy to both manufacture and install.
It i~ a further object of the present invention to provide a liner assembly formed of rotocast liner sections which are ~ecurely and - permanently anchored to the cast manhole sections.
Still another object of the present invention is to provide a connector for manhole assemblies and the like which provides a corrosion resistant water-tight connection between entry castings and precast concrete cones and flat-top sections and enables grade adjustments without the need for added parts.
In the accompanying drawings:
Fig. 1 is a sectional view of a manhole assembly embodying the principles of the present invention.
Fig. la, lb and lc are detailed sectional views showing the sealants employed between adjacent manhole sections.
Fig. 2 is a perspective view, partially sectionalized, showing the interior of the liners in ne manhole section of Fig. 1.
Fig. 2a is a detailed sectional view of a portion of Fig. 2 shown encircled.
Fig. 2b is a perspective view, partially sectionalized, showing the arrangement of two liner section and a reinforcing mesh cage surrounding the liner sections and the members anchoring the liners of the cage.
Fig. 2c is a detailed sectional view of Fig. 2b showing the portion of Fig. 2b encircled.
- Fig. 3 shows simplified top plan vlew of liner sections joined together.
Fig. 3a is a top view showing one of the clamping assemblies of Fig. 3 in grater detail.
-Fig. 3b is a top view similar to that shown in Fig. 3a showing an alternative fastening clip .
Fig. 4 shows a top plan view of a liner for use with the slab top section of a type shown in Fig. 1.
Fig. 4a is a sectional view of Fig. 4 looking in the direction of arrows 4a-4a of Fig. 4.
Fig. 4b is a sectional view looking in the direction of arrows 4b-4b of Fig. 4c;
Fig. 4c is an elevational view of Fig. 4 with a number of the reinforcing ribs removed to simplify the figure.
Fig. 5 is a detailed view showing the manner in which a manhole gasket is assembled with a liner in a mold for casting a manhole section.
Fig. 5a is an exploded sectional view of the mandrel assembly.
Fig. 5b is an enlarged and detailed cross-section of the gasket of Fig. 5.
Fig. 6a shows a top view of a molding tool used in rotocasting liner sections.
Fig. 6b shows one of the end caps secured to top and bottom ends of the molding tool.
Fig. 6c is an interior side view of one of the panel forming sections employed in the mold tool of Fig. 6a.
Fig. 1 shows one typical manhole assembly 10 comprising a manhole base 20, riser section 30 and top section 40, each being of a cylindrical-shape. Top section 40 is typically shorter than sections 20 and 30 and provides a top opening which g is eccentrically aligned for receiving a cast iron frame 50 and sewer lid cover 52, which opening is aligned with the ladder steps to enable service personnel to gain access to the interior thereof.
Although the assembly 10 utilizes a slab top 45, a cone-shaped top may be employed.
Members 20, 30 ahd 40 are formed of concrete and each has a metal reenforcing framework or cage comprised of a grid work of mutually perpendicularly aligned rods. For example, note the rods 21 and 22 shown in section 20 of Fig. 1. It should be understood that a number of vertical rods 21 are arranged at a substantially equispaced intervals about the circumference of section 20 to make up the wire mesh cage.
Base 20 is typically provided with two openings only one of which is shown at 25, each opening receiving one end of a pipe section, inserted into the base section from the exterior thereof. Resilient rubber-like seal 26 is preferably integrally cast into the base member although it can be hydraulically placed after the opening is either cast or cored to provide a water-tight seal between the pipe section (not shown) and base section 25. An interior shoulder 27 is provided along the top edge of base 20 and has an outer projection 28 surrounding shoulder 27.
Riser section 30 has a like reenforcement cage structure comprised of mutually perpendicularly aligned steel rods 31 and 32. An outer shoulder 33 at the bottom of section 30 rests upon projection 28 and an inner projection 34 rests upon shoulder 27.
The top end of riser section 30 is provided with an inner shoulder 35 have a projection 43 provided that the bottom of section 40 resting thereon. An outer projection 36 at the top of section 30 has an outer shoulder 44 of section 40 resting thereon. The inner shoulder 35 supports an inner projection 43 of top section 40.
Similar to sections 20 and 30, top section 40 is likewise provided with a wire reinforcement comprised of mutually perpendicular wires or rods 41 or 42.
A water lock entry sleeve 47, to be more fully described is provided to protect the cast material forming opening 46.
A circular shaped protective liner 49 has a portion 49a extending into a lower portion of opening 46 and cooperates with sleeve 47, which is telescopingly received within portion 49a, to provide water tight corrosion protection. The water tight seal is obtained through the use of O-rings which will be described hereinbelow.
Sections 20 and 30 have corrosion protecting liner assemblies 60 and 70, each of which lines the interior surface of its associated manhole, and thereby protects the surface from corrosion and deterioration.
Figs. la, lb and lc show three different techniques for providing a water tight seal between adjacent manhole sections which are stacked one upon the other. In Fig. la, a substantially toroidal shaped rubber gasket 90 having an annular cross-section is arranged upon a small shoulder as shown.
A strip of butyl material 92 is arranged upon projection 28. Gasket 90 is lubricated preparatory to its placement. The butyl strip has its right-hand end set back approximately one-quarter inch from the outer diameter of the manhole section 20.
Fig. lb shows an arrangement in which a - "spigot up" joint receives a butyl strip over the top of projection 28, and extending downwardly along the tapered surface 28a. This arrangement is used in manhole assemblies having 48-60 inch diameters.
Fig. lc shows the arrangement utilized in manhole assemblies having 72-144 inch diameters wherein the first butyl strip 92 is placed upon the surface of projection 28 so that its right-hand end is set back approximately three-quarters of an inch.
A second butyl strip 94 has a portion thereof resting upon inner shoulder 27 and extending upwardly along the tapered surface 28a.
The liner assemblies are comprised of a plurality of liner sections, three such liner sections being provided in one of the preferred embodiments described herein. Two such liner sections 100' and 100" are shown in Fig. 2. The liner sections have outwardly directed flanges 102', 102" and 103', 103" at the upper and lower ends thereof said flanges engaging flanges of adjacent liner assemblies as will be more fully described hereinbelow.
A suitable sealant is provided between adjacent flanges to assure a water tight corrosion seal in the region of mating flanges. Figs. 4a, 4b and 4c show the manner in which sealing material is arranged along the mating surfaces to provide the desired water tight seal.
Figs. 2, 2a and 2b show details of the manner in which the liner sections which are joined along vertical flanges or returns, are anchored to the wire mesh reinforcement, and are thereby securely fixed within the cast member.
Sections 100', 100", which are roto-cast in a manner to be more fully described, are joined by joining clips 110 and are arranged within mold members, not shown for purposes of simplicity, preparatory to a casting operation. A wire mesh reinforcement cage comprised of the plurality of vertically aligned spaced parallel wire members 21 which are joined to a plurality of horizontally aligned spaced parallel wires 22 which form closed circular members that are affixed to, welded to or otherwise joined to the vertical members 21. Each of the liner sections 100', 100" is provided with a plurality of arcuate-shaped reinforcement ribs which are substantially horizontally aligned, and arranged in spaced parallel fashion to one another, the ribs being provided with holes or openings 106a" shown in Figs. 2b and 2c. Plastic wrap-it ties typically referred to as nylon ties, have a female locking member at one end for receiving an opposite end of the tie member which, once inserted, cannot be pulled out. The tie members are threaded through the openings 106a" and wrapped about either the horizontal wires 22 or the vertical wires 21 or both thereby anchoring the liner sections and centering the liner sections within the casting mold. The ties 108 have a 100 pound pull strength capability.
The number of ties utilized may vary over a wide range. In the preferred embodiment, two ties are typically arranged at approximately six (6) inch inwardly spaced horizontal intervals from the vertical sides of each liner with a third tie arranged at the center of the rib. Every other rib is anchored in this manner. The "intervening" ribs have only two ties equi-distant from the center position and six (6) inches in from the ends of the ribs. The top rib overlies the top lip of the cast - member.
The ties are tightened to form four (4) inch circles.
As was set forth hereinabove, each of the liner sections is provided with a pair of returns or flanges which are substantially vertically aligned when cast into the manhole sections. Fig. 3 shows a top plan view of three liner sections 100, 100' and 100" joined together to form a circular liner a~sembly, e.g. the liner assemblies 60 and 70, by means of an elongated polyethylene clip 109. Each of the liner sections is provided with returns 105 along opposite vertical sides. An elongated resilient, compressible foam rubber strip preferably formed of a EPDM compound is placed between the confronting surfaces of the returns 105, as shown in Fig. 3a. The returns are pressed together and the elongated polyethylene clip is aligned with returns 105 and is slid onto the returns to provide the locking assembly shown in Fig. 3a. Clip 109 is substantially C-shaped, and embraces and holds the bulging portions 105a of the returns 105 being joined. Strip 110 is compressed therebetween aiding clip 109 in ret~;n;ng a superior locking grip on the returns while at the same time providing a water tight seal along the vertical seam between adjacent panels.
In addition thereto, the substantially T-shaped configuration further acts as a further means to anchor the liner sections within the cast member at the three locations shown in Fig. 3 spaced at 120 intervals.
The ends of the reinforcing ribs 106 have tapered portions 106b to provide adequate clearance for clip 109.
Fig. 3b shows an alternative embodiment wherein a stainless steel clip 112 may be substituted for polyethylene clip 109 shown in Fig.
3a. Clip 112 may either be slid into position in the same manner as was described hereinabove with regard to clip 109 or alternatively may be snapped into position, for example, by orienting the clip so that its right-hand end embraces the right-hand return 105 and then snapping the clip over the bulge 105a of the left-hand return 105. As a further alternative, although it is preferred that the plastic clip 109 be a continuous one-piece member extending the height of the liner sections, shorter clip lengths may be utilized. It is nevertheless preferred that adjacent edges of clip lengths be in engagement since a liquid tight seal is desired over the entire length of the seam. The stainless steel clip assembly may likewise be a plurality of shorter length clip sections also preferably arranged so that adjacent edges of the shorter clip lengths are in engagement.
Fig. 4 shows a top plan view of the liner 49 employed to protect the slab top 45.
The liner 49 has a substantially circular shape and the major portion thereof is substantially flat and is provided with a plurality of reinforcing ribs 49b. A profile of the liner, with most of the ribs removed for simplicity, is shown in Fig. 4c looking in the direction of arrows 4c-4c in Fig. 4.
The slab top liner 49 has an eccentric opening, and surrounding the opening there is provided a stepped cylindrical extension 49c whose 21 62357 `
bottom portion is integrally formed and joined with the flat, circular portion of the liner as is shown in Figs. 4a and 4c. The cylinder has a first diameter portion 49d, which tapers at 49e to define a smaller diameter portion 49f, the top end of which terminates in an outwardly directed flange 49g. A
hollow cylindrical extension 47 having an outer diameter which is slightly less than the inner diameter of the cylindrical portion 49f, is telescopingly received within the stepped cylindrical projection 49. The upper end of the cylindrical extension 47 has an outwardly directed annular flange 47a, which is arranged to be secured between a top one of a plurality of grade rings and a cover frame 50, which, as is conventional, is provided with a supporting flange 5Oa resting upon flange 47a and a flange 50b for positioning and supporting a manhole cover member, not shown for purposes of simplicity.
The number of grade rings 120 employed is dependent upon the spacing required between the cover frame 50 and the top surface of slab 45. It should further be understood that additional grade rings may be inserted or one or more grade rings may be removed or grade rings of different thickness may be substituted to accommodate any changes in the spacing between the top surface of top slab 45 and grade level.
The telescoping cylindrical section 47, in one preferred embodiment, is provided with a substantially corrugated cross-section taken in the vertical direction so as to form a plurality of spaced annular recesses arranged at spaced intervals along the outer periphery, any one or more of the recesses being adapted to receive and support an 0-ring 53. One or more O-rings may be provided as shown in Fig. 4a. The three O-rings 53 shown in Fig. 4a are formed of a suitable resilient, compressible rubber or rubber-like material, which is compressed between the cylindrical section 47 and the inner periphery of smaller diameter portion 49f.
The stepped cylindrical projection 49 protects the top slab 45 from corrosion. The water tight seal provided by the O-rings in cooperation with the stepped cylindrical projection 49 and the telescoping cylindrical section 47 protects grade rings from corrosion.
The opening 25 for receiving a pipe or conduit is preferably formed during the casting operation, and as was mentioned hereinabove, a gasket 26 is anchored in the cast material by holding gasket 26 with a mandrel assembly 130 as shown in Figs. 5 and 5a, and comprised of outer and inner mandrel members 132 and 134 shown in exploded fashion in Fig. 5a. Interior mandril member 134 has a central section 134a and a truncated conical shaped portion 134b integrally joined thereto.
Outer mandrel section 132 has a central portion 132a, a first truncated conical portion 132b joined thereto and a second truncated conical portion 132c integrally joined to truncated portion 132b, as shown. A threaded member 135 having a head 135a and threaded portion 135b is secured to the central portion 134a. A thick reinforcing member 136 is secured to the central portion 132a so that openings 132c and 136a are concentric and are axially aligned.
A resilient compressible gasket formed o~
a suitable rubber or rubber-like material for example, polyisoprene, and which is extruded, cut to length and formed into an annular shape has its free ends joined together by a suitable solvent, epoxy, vulcanization, or other suitable techniques to form a continuous annular gasket. A cross-section of gasket 140 is shown in Fig. 5b and is comprised of a substantially T-shaped portion defined by a head portion 140a and a tapered portion 140b joining the head portion to the main body portion of 140c of the gasket. The main body portion has a triangular shaped cross-section. A
diagonally aligned flange 140d is integral with the left-hand end of the gasket, as shown in Fig. 5b.
A plurality of hollow, continuous, annular cavities 140e-140h are provided in the main body portion of the gasket and function in the manner to be more fully described.
Preparatory to the introduction of the cast material (i.e. concrete) into the mold, openings are cut or otherwise formed in the wire mesh reinforcement 21, 22 and in the appropriate liner section or sections.
The ann~ular gasket 140 is fitted into the opening in the liner section 100 as shown in Fig. 5 so that the flange 140d overlies a marginal portion of the interior periphery of liner section 100 to provide a liquid seal therealong. The internal and external mandrel members are then positioned in the manner shown in Fig. 5 and are secured to one another by fastener F to embrace the surfaces 140j, 140k, which surfaces extend generally inwardly toward the center line extending substantially through the axis of threaded member 135b. The cast material is poured into the mold and forms about the exterior mandrel 132, which serves to define the opening through the cast member which is aligned with the openings in the gasket and the liner section.
- When the cast material is set, fastener F
is loosened and removed, and the mandrel sections 132 and 134 are withdrawn respectively in the inward and outward direction.
The T-shaped portion of the gasket is embraced by the cast material assuring that the gasket is properly anchored in and fixedly secured to the cast member.
When a manhole section having an opening therein is installed at a field site, a pipe or conduit is inserted into the cast member in the direction shown by arrow A in Fig. 5. The pipe being inserted and the gasket are selected so that the outer diameter of the pipe is greater than the inner diameter D of the gasket. The tapered surface 140j serves the dual functions of guiding the pipe into the manhole section, and further collapsing and/or compressing as the pipe is inserted beyond the apex 140m of the gasket (see Fig. 5b), the apex 140m thus moves closer toward flange 140d. Cavities 140e-140h begin to collapse in a controlled manner to provide different amounts of compression which assures better centering of the pipe within gasket 140, further placing the resilient compressible material at that portion of the gasket where it is most needed.
As was mentioned hereinabove, the liner sections of the present invention are produced using a rotocast assembly method. Figs. 6, 6a and 6b show one suitable mold for casting the curved liner sections 100, the mold assembly 160, which is fabricated to substantially resemble an elliptical cylinder comprised of curved mold sections 1162, 162 which are substantially mirror images of one another. Fig. 6c shows one mold section 162 looking in the direction of arrows 6c, 6c shown in Fig. 6a.
A plurality of spaced, parallel recesses 162a are provided within the mold section to define the curved reinforcing ribs. The sides 162b, 162c of each mold section are secured by fasteners F to elongated joining members 163 in the manner shown in Fig. 6a. The top and bottom surfaces of each mold section 162 are provided with a plurality of openings 162e, which receive fastening members (not shown) for securely but releaseably mounting top and bottom mold caps, one such mold cap 164 being shown in Fig. 6b. Each mold cap is provided with a lS plurality of openings 164a for receiving the aforementioned fastening members to secure the mold cap to the top 162d and bottom 162c ends of the mold sections 162. Additional openings are similar to openings 164a are provided at the top and bottom ends thereof for securing the end caps to the top and bottom sections 163. Openings 164a are aligned with the openings 162e.
The mold material, which is preferably polyethylene, is inserted into the rotor casting mold assembly 160, which is mounted upon a suitable turntable, and rotated, typically at an angular velocity suitable to drive the mold material into the mold sections, thereby forming a pair of panels.
More particularly, polyethylene in powdered form is inserted into the tool. When the cover caps are securely fastened to the mold tool, the assembly is mounted upon a platform capable of rotating in three (3) mutually perpendicular directions.
The mold assembly is heated as it is spun.
- When a proper temperature is obtained for a suitable time period, the mold assembly is transferred to a cooling station where it is cooled as the mold continues to spin. When the mold is cooled for a sufficient period, it is sent to a stripping station where the liner sections are removed. The process is the same for each of the liner members of the manhole sections with the only exception being that the mold obviously differ for different sections.
In addition, although Fig. 1 discloses a manhole assembly with a slab top and a liner therefor when desired, a cone-shaped top can be substituted therefor and liner sections to line the interior of a cone-shaped top may also be produced using the rotocast method.
Each panel represents one-third of the circumference of a manhole section to be cast. The mold sections 162 are of a suitable height. The ribs or returns are spaced at six inch centers enabling the panels to be cut down to the desired height.
As was described hereinabove, the returns along the vertical sides of the liner sections cooperate to form a substantially T-shaped configuration when the panels are positioned side-by-side, enabling the C-shaped clip to be driven over the top of the T-shaped arrangement, to provide an effective seal.
The non-corrosive ties, preferably nylon tie members, which are looped through the reinforcing ribs at about the wire reinforcement significantly increase the liner's ability to withstand pull-out or loss of shape due to hydrostatic pressure, the anchoring strength resulting from the solid cross-section of the rotor cast ribs.
The employment of low density liner polyethylene as the molding material provides the Sliners with excellent abrasion and chemical resistance, high impact resistance, and the ability - to withstand a multitude of welding methods to fabricate custom designs, fasten appurtenances thereto and/or facilitate field repairs.
10The uniform size liner sections, which require separate molding means for manhole sections of each standard diameter may be mass produced, and conveniently stored in a compact manner for use either in-situ casting in new construction or 15rehabilitation of existing underground structures, the design herein elim;n~ting the need for custom fabrication on a job site.
The present invention is characterized by comprising a method and apparatus for resolving the disadvantages of present day design including among them those discussed hereinabove, as well as - delivering significant improvements in manufacturing, assembly and casting as well as field installation and performance of the entire system.
5The present invention is characterized by utilizing a rotocasting process for molding panels, preferably from polyethylene, through the use of a tool fabricated to resemble an elliptical cylinder utilized to form two panels simultaneously. In one 10preferred embodiment, each panel represents one-third of the desired circumference of a cylindrical shaped cast member.
Tooling requirements are minimized by utilization of a tool having a standard length 15determined by the diameter of the cast member and having reenforcing ribs equally spaced along the height of the tool by a predetermined distance enabling panels to be cut down to a desired shorter height.
20The tool utilized to cast the liner sections and containing the mold material is spun by suitable drive means to simultaneously form a pair of rotocast liner members having substantially solid flanges, reenforcing ribs and joining ribs which act 25to provide curved liner sections having excellent structural strength to prevent warping and buckling and which are joined by suitable plastic ties to the internal wire mesh of the cast member, thereby providing excellent anchoring of the liner sections 30to the cast material. This arrangement provides an anchoring arrangement which has a significantly improved capability of being properly centered and retaining its curved shape without buckling, bending or warping as compared with the roto-cast liners disclosed in U. S. Patent No. 5,303,518, issued April 19, 1994.
The liner sections, preparatory to placement within the casting mold, are joined to one another by a clip which slides over a pair of returns or flanges of adjacent liner sections, locking the returns to one another and squeezing a resilient compressible foam rubber strip positioned between adjacent surfaces of the joined returns which assures a water-tight seam therebetween. The clip also serves as a fluid barrier over the entire length of the seam.
The clip member joining vertical returns of adjacent liner sections may be either a plastic clip assembly or a stainless clip assembly, the latter being capable of either being slipped or snap-fitted into position.
The liner and plastic clip are preferably formed of polyethylene which inert to substantially all of the toxic materials encountered in sewage systems yielding excellent protection for the cast material. In addition, polyethylene prevent leaching.
Gasketing is provided between vertically stacked sections of the manhole assembly to provide a water-tight seal between the manhole base and riser sections and between the riser section (or sections) and the top section. Flanges are provided on the liners at the upper ends thereof to provide corrosive protection along the interior region of the joined manhole sections.
Openings are formed in the liner section at those Locations designated for receipt of a conduit. A connector mandrel arranged within the mold preparatory to casting supports a gasket for water-tightly sealing a conduit or pipe inserted into the manhole assembly, the gasket being provided with a continuous outer flange having a substantially T-shaped cross-section for anchoring the gasket in the cast material. The main body portion of the gasket is provided with a plurality of continuous annular voids of varying lengths which are diagonally oriented to control the resiliency and compression of the gasket during the insertion of conduit thereby assuring placement of the gasket material where it is needed most for supporting and water-tightly sealing a conduit inserted therein.
A top liner member is provided for protecting the roof of the manhole assembly. The substantially circular-shaped top liner is provided with reenforcing ribs and a substantially stepped cylindrical projection defining an eccentric opening in the top liner. The reenforcing ribs of the slab top liner are joined to a wire reenforcement embedded in the cast member by non-corrosive tie members. The generally cylindrical-shaped access opening portion of the liner is integral with the disk-shaped portion and cooperates with a hollow, cylindrical-shaped extension member telescopically received within the stepped, cylindrical-shaped projection extending upwardly from the top liner.
One or more O-rings are arranged in seating recesses arranged about the outer periphery of the cylindrical extension member to provide an adjustable, water-tight seal between the telescoping members.
The sealants employed between adjacent vertically aligned sections of the manhole assembly may be EPDM which are employed in waste-water applications and nitrile gaskets for use in .
applications in which oil and fluorocarbon materials are encountered.
5It is therefore one object of the present invention to provide precast concrete vertical placed structures, manhole assemblies or the like having novel rotocast liner assemblies impervious to toxic materials for protecting the concrete.
10Still another object of the present invention is to provide a novel liner assembly for lining and protecting annular concrete structures and the like from corrosion, the liner assembly being formed of liner sections having integral 15returns joined to one another by fastening clips, eliminating the need for conventional fasteners and having resilient gasket means arranged between adjacent surfaces of the returns for providing an excellent water-tight seal along the clip assembly.
20Another object of the present invention is to provide novel liner sections joined to one another with slide-on clip means and having reenforcing ribs which are anchored to the cast concrete by means of ties permanently anchoring the 25liners to the wire mesh reenforcement of the cast member to assure retention of the liner section curvilinear-shape and to present bulging or warping.
Still another object of the present lnvention is to provide a liner assembly for lining 30manholes and the like and which is easy to both manufacture and install.
It i~ a further object of the present invention to provide a liner assembly formed of rotocast liner sections which are ~ecurely and - permanently anchored to the cast manhole sections.
Still another object of the present invention is to provide a connector for manhole assemblies and the like which provides a corrosion resistant water-tight connection between entry castings and precast concrete cones and flat-top sections and enables grade adjustments without the need for added parts.
In the accompanying drawings:
Fig. 1 is a sectional view of a manhole assembly embodying the principles of the present invention.
Fig. la, lb and lc are detailed sectional views showing the sealants employed between adjacent manhole sections.
Fig. 2 is a perspective view, partially sectionalized, showing the interior of the liners in ne manhole section of Fig. 1.
Fig. 2a is a detailed sectional view of a portion of Fig. 2 shown encircled.
Fig. 2b is a perspective view, partially sectionalized, showing the arrangement of two liner section and a reinforcing mesh cage surrounding the liner sections and the members anchoring the liners of the cage.
Fig. 2c is a detailed sectional view of Fig. 2b showing the portion of Fig. 2b encircled.
- Fig. 3 shows simplified top plan vlew of liner sections joined together.
Fig. 3a is a top view showing one of the clamping assemblies of Fig. 3 in grater detail.
-Fig. 3b is a top view similar to that shown in Fig. 3a showing an alternative fastening clip .
Fig. 4 shows a top plan view of a liner for use with the slab top section of a type shown in Fig. 1.
Fig. 4a is a sectional view of Fig. 4 looking in the direction of arrows 4a-4a of Fig. 4.
Fig. 4b is a sectional view looking in the direction of arrows 4b-4b of Fig. 4c;
Fig. 4c is an elevational view of Fig. 4 with a number of the reinforcing ribs removed to simplify the figure.
Fig. 5 is a detailed view showing the manner in which a manhole gasket is assembled with a liner in a mold for casting a manhole section.
Fig. 5a is an exploded sectional view of the mandrel assembly.
Fig. 5b is an enlarged and detailed cross-section of the gasket of Fig. 5.
Fig. 6a shows a top view of a molding tool used in rotocasting liner sections.
Fig. 6b shows one of the end caps secured to top and bottom ends of the molding tool.
Fig. 6c is an interior side view of one of the panel forming sections employed in the mold tool of Fig. 6a.
Fig. 1 shows one typical manhole assembly 10 comprising a manhole base 20, riser section 30 and top section 40, each being of a cylindrical-shape. Top section 40 is typically shorter than sections 20 and 30 and provides a top opening which g is eccentrically aligned for receiving a cast iron frame 50 and sewer lid cover 52, which opening is aligned with the ladder steps to enable service personnel to gain access to the interior thereof.
Although the assembly 10 utilizes a slab top 45, a cone-shaped top may be employed.
Members 20, 30 ahd 40 are formed of concrete and each has a metal reenforcing framework or cage comprised of a grid work of mutually perpendicularly aligned rods. For example, note the rods 21 and 22 shown in section 20 of Fig. 1. It should be understood that a number of vertical rods 21 are arranged at a substantially equispaced intervals about the circumference of section 20 to make up the wire mesh cage.
Base 20 is typically provided with two openings only one of which is shown at 25, each opening receiving one end of a pipe section, inserted into the base section from the exterior thereof. Resilient rubber-like seal 26 is preferably integrally cast into the base member although it can be hydraulically placed after the opening is either cast or cored to provide a water-tight seal between the pipe section (not shown) and base section 25. An interior shoulder 27 is provided along the top edge of base 20 and has an outer projection 28 surrounding shoulder 27.
Riser section 30 has a like reenforcement cage structure comprised of mutually perpendicularly aligned steel rods 31 and 32. An outer shoulder 33 at the bottom of section 30 rests upon projection 28 and an inner projection 34 rests upon shoulder 27.
The top end of riser section 30 is provided with an inner shoulder 35 have a projection 43 provided that the bottom of section 40 resting thereon. An outer projection 36 at the top of section 30 has an outer shoulder 44 of section 40 resting thereon. The inner shoulder 35 supports an inner projection 43 of top section 40.
Similar to sections 20 and 30, top section 40 is likewise provided with a wire reinforcement comprised of mutually perpendicular wires or rods 41 or 42.
A water lock entry sleeve 47, to be more fully described is provided to protect the cast material forming opening 46.
A circular shaped protective liner 49 has a portion 49a extending into a lower portion of opening 46 and cooperates with sleeve 47, which is telescopingly received within portion 49a, to provide water tight corrosion protection. The water tight seal is obtained through the use of O-rings which will be described hereinbelow.
Sections 20 and 30 have corrosion protecting liner assemblies 60 and 70, each of which lines the interior surface of its associated manhole, and thereby protects the surface from corrosion and deterioration.
Figs. la, lb and lc show three different techniques for providing a water tight seal between adjacent manhole sections which are stacked one upon the other. In Fig. la, a substantially toroidal shaped rubber gasket 90 having an annular cross-section is arranged upon a small shoulder as shown.
A strip of butyl material 92 is arranged upon projection 28. Gasket 90 is lubricated preparatory to its placement. The butyl strip has its right-hand end set back approximately one-quarter inch from the outer diameter of the manhole section 20.
Fig. lb shows an arrangement in which a - "spigot up" joint receives a butyl strip over the top of projection 28, and extending downwardly along the tapered surface 28a. This arrangement is used in manhole assemblies having 48-60 inch diameters.
Fig. lc shows the arrangement utilized in manhole assemblies having 72-144 inch diameters wherein the first butyl strip 92 is placed upon the surface of projection 28 so that its right-hand end is set back approximately three-quarters of an inch.
A second butyl strip 94 has a portion thereof resting upon inner shoulder 27 and extending upwardly along the tapered surface 28a.
The liner assemblies are comprised of a plurality of liner sections, three such liner sections being provided in one of the preferred embodiments described herein. Two such liner sections 100' and 100" are shown in Fig. 2. The liner sections have outwardly directed flanges 102', 102" and 103', 103" at the upper and lower ends thereof said flanges engaging flanges of adjacent liner assemblies as will be more fully described hereinbelow.
A suitable sealant is provided between adjacent flanges to assure a water tight corrosion seal in the region of mating flanges. Figs. 4a, 4b and 4c show the manner in which sealing material is arranged along the mating surfaces to provide the desired water tight seal.
Figs. 2, 2a and 2b show details of the manner in which the liner sections which are joined along vertical flanges or returns, are anchored to the wire mesh reinforcement, and are thereby securely fixed within the cast member.
Sections 100', 100", which are roto-cast in a manner to be more fully described, are joined by joining clips 110 and are arranged within mold members, not shown for purposes of simplicity, preparatory to a casting operation. A wire mesh reinforcement cage comprised of the plurality of vertically aligned spaced parallel wire members 21 which are joined to a plurality of horizontally aligned spaced parallel wires 22 which form closed circular members that are affixed to, welded to or otherwise joined to the vertical members 21. Each of the liner sections 100', 100" is provided with a plurality of arcuate-shaped reinforcement ribs which are substantially horizontally aligned, and arranged in spaced parallel fashion to one another, the ribs being provided with holes or openings 106a" shown in Figs. 2b and 2c. Plastic wrap-it ties typically referred to as nylon ties, have a female locking member at one end for receiving an opposite end of the tie member which, once inserted, cannot be pulled out. The tie members are threaded through the openings 106a" and wrapped about either the horizontal wires 22 or the vertical wires 21 or both thereby anchoring the liner sections and centering the liner sections within the casting mold. The ties 108 have a 100 pound pull strength capability.
The number of ties utilized may vary over a wide range. In the preferred embodiment, two ties are typically arranged at approximately six (6) inch inwardly spaced horizontal intervals from the vertical sides of each liner with a third tie arranged at the center of the rib. Every other rib is anchored in this manner. The "intervening" ribs have only two ties equi-distant from the center position and six (6) inches in from the ends of the ribs. The top rib overlies the top lip of the cast - member.
The ties are tightened to form four (4) inch circles.
As was set forth hereinabove, each of the liner sections is provided with a pair of returns or flanges which are substantially vertically aligned when cast into the manhole sections. Fig. 3 shows a top plan view of three liner sections 100, 100' and 100" joined together to form a circular liner a~sembly, e.g. the liner assemblies 60 and 70, by means of an elongated polyethylene clip 109. Each of the liner sections is provided with returns 105 along opposite vertical sides. An elongated resilient, compressible foam rubber strip preferably formed of a EPDM compound is placed between the confronting surfaces of the returns 105, as shown in Fig. 3a. The returns are pressed together and the elongated polyethylene clip is aligned with returns 105 and is slid onto the returns to provide the locking assembly shown in Fig. 3a. Clip 109 is substantially C-shaped, and embraces and holds the bulging portions 105a of the returns 105 being joined. Strip 110 is compressed therebetween aiding clip 109 in ret~;n;ng a superior locking grip on the returns while at the same time providing a water tight seal along the vertical seam between adjacent panels.
In addition thereto, the substantially T-shaped configuration further acts as a further means to anchor the liner sections within the cast member at the three locations shown in Fig. 3 spaced at 120 intervals.
The ends of the reinforcing ribs 106 have tapered portions 106b to provide adequate clearance for clip 109.
Fig. 3b shows an alternative embodiment wherein a stainless steel clip 112 may be substituted for polyethylene clip 109 shown in Fig.
3a. Clip 112 may either be slid into position in the same manner as was described hereinabove with regard to clip 109 or alternatively may be snapped into position, for example, by orienting the clip so that its right-hand end embraces the right-hand return 105 and then snapping the clip over the bulge 105a of the left-hand return 105. As a further alternative, although it is preferred that the plastic clip 109 be a continuous one-piece member extending the height of the liner sections, shorter clip lengths may be utilized. It is nevertheless preferred that adjacent edges of clip lengths be in engagement since a liquid tight seal is desired over the entire length of the seam. The stainless steel clip assembly may likewise be a plurality of shorter length clip sections also preferably arranged so that adjacent edges of the shorter clip lengths are in engagement.
Fig. 4 shows a top plan view of the liner 49 employed to protect the slab top 45.
The liner 49 has a substantially circular shape and the major portion thereof is substantially flat and is provided with a plurality of reinforcing ribs 49b. A profile of the liner, with most of the ribs removed for simplicity, is shown in Fig. 4c looking in the direction of arrows 4c-4c in Fig. 4.
The slab top liner 49 has an eccentric opening, and surrounding the opening there is provided a stepped cylindrical extension 49c whose 21 62357 `
bottom portion is integrally formed and joined with the flat, circular portion of the liner as is shown in Figs. 4a and 4c. The cylinder has a first diameter portion 49d, which tapers at 49e to define a smaller diameter portion 49f, the top end of which terminates in an outwardly directed flange 49g. A
hollow cylindrical extension 47 having an outer diameter which is slightly less than the inner diameter of the cylindrical portion 49f, is telescopingly received within the stepped cylindrical projection 49. The upper end of the cylindrical extension 47 has an outwardly directed annular flange 47a, which is arranged to be secured between a top one of a plurality of grade rings and a cover frame 50, which, as is conventional, is provided with a supporting flange 5Oa resting upon flange 47a and a flange 50b for positioning and supporting a manhole cover member, not shown for purposes of simplicity.
The number of grade rings 120 employed is dependent upon the spacing required between the cover frame 50 and the top surface of slab 45. It should further be understood that additional grade rings may be inserted or one or more grade rings may be removed or grade rings of different thickness may be substituted to accommodate any changes in the spacing between the top surface of top slab 45 and grade level.
The telescoping cylindrical section 47, in one preferred embodiment, is provided with a substantially corrugated cross-section taken in the vertical direction so as to form a plurality of spaced annular recesses arranged at spaced intervals along the outer periphery, any one or more of the recesses being adapted to receive and support an 0-ring 53. One or more O-rings may be provided as shown in Fig. 4a. The three O-rings 53 shown in Fig. 4a are formed of a suitable resilient, compressible rubber or rubber-like material, which is compressed between the cylindrical section 47 and the inner periphery of smaller diameter portion 49f.
The stepped cylindrical projection 49 protects the top slab 45 from corrosion. The water tight seal provided by the O-rings in cooperation with the stepped cylindrical projection 49 and the telescoping cylindrical section 47 protects grade rings from corrosion.
The opening 25 for receiving a pipe or conduit is preferably formed during the casting operation, and as was mentioned hereinabove, a gasket 26 is anchored in the cast material by holding gasket 26 with a mandrel assembly 130 as shown in Figs. 5 and 5a, and comprised of outer and inner mandrel members 132 and 134 shown in exploded fashion in Fig. 5a. Interior mandril member 134 has a central section 134a and a truncated conical shaped portion 134b integrally joined thereto.
Outer mandrel section 132 has a central portion 132a, a first truncated conical portion 132b joined thereto and a second truncated conical portion 132c integrally joined to truncated portion 132b, as shown. A threaded member 135 having a head 135a and threaded portion 135b is secured to the central portion 134a. A thick reinforcing member 136 is secured to the central portion 132a so that openings 132c and 136a are concentric and are axially aligned.
A resilient compressible gasket formed o~
a suitable rubber or rubber-like material for example, polyisoprene, and which is extruded, cut to length and formed into an annular shape has its free ends joined together by a suitable solvent, epoxy, vulcanization, or other suitable techniques to form a continuous annular gasket. A cross-section of gasket 140 is shown in Fig. 5b and is comprised of a substantially T-shaped portion defined by a head portion 140a and a tapered portion 140b joining the head portion to the main body portion of 140c of the gasket. The main body portion has a triangular shaped cross-section. A
diagonally aligned flange 140d is integral with the left-hand end of the gasket, as shown in Fig. 5b.
A plurality of hollow, continuous, annular cavities 140e-140h are provided in the main body portion of the gasket and function in the manner to be more fully described.
Preparatory to the introduction of the cast material (i.e. concrete) into the mold, openings are cut or otherwise formed in the wire mesh reinforcement 21, 22 and in the appropriate liner section or sections.
The ann~ular gasket 140 is fitted into the opening in the liner section 100 as shown in Fig. 5 so that the flange 140d overlies a marginal portion of the interior periphery of liner section 100 to provide a liquid seal therealong. The internal and external mandrel members are then positioned in the manner shown in Fig. 5 and are secured to one another by fastener F to embrace the surfaces 140j, 140k, which surfaces extend generally inwardly toward the center line extending substantially through the axis of threaded member 135b. The cast material is poured into the mold and forms about the exterior mandrel 132, which serves to define the opening through the cast member which is aligned with the openings in the gasket and the liner section.
- When the cast material is set, fastener F
is loosened and removed, and the mandrel sections 132 and 134 are withdrawn respectively in the inward and outward direction.
The T-shaped portion of the gasket is embraced by the cast material assuring that the gasket is properly anchored in and fixedly secured to the cast member.
When a manhole section having an opening therein is installed at a field site, a pipe or conduit is inserted into the cast member in the direction shown by arrow A in Fig. 5. The pipe being inserted and the gasket are selected so that the outer diameter of the pipe is greater than the inner diameter D of the gasket. The tapered surface 140j serves the dual functions of guiding the pipe into the manhole section, and further collapsing and/or compressing as the pipe is inserted beyond the apex 140m of the gasket (see Fig. 5b), the apex 140m thus moves closer toward flange 140d. Cavities 140e-140h begin to collapse in a controlled manner to provide different amounts of compression which assures better centering of the pipe within gasket 140, further placing the resilient compressible material at that portion of the gasket where it is most needed.
As was mentioned hereinabove, the liner sections of the present invention are produced using a rotocast assembly method. Figs. 6, 6a and 6b show one suitable mold for casting the curved liner sections 100, the mold assembly 160, which is fabricated to substantially resemble an elliptical cylinder comprised of curved mold sections 1162, 162 which are substantially mirror images of one another. Fig. 6c shows one mold section 162 looking in the direction of arrows 6c, 6c shown in Fig. 6a.
A plurality of spaced, parallel recesses 162a are provided within the mold section to define the curved reinforcing ribs. The sides 162b, 162c of each mold section are secured by fasteners F to elongated joining members 163 in the manner shown in Fig. 6a. The top and bottom surfaces of each mold section 162 are provided with a plurality of openings 162e, which receive fastening members (not shown) for securely but releaseably mounting top and bottom mold caps, one such mold cap 164 being shown in Fig. 6b. Each mold cap is provided with a lS plurality of openings 164a for receiving the aforementioned fastening members to secure the mold cap to the top 162d and bottom 162c ends of the mold sections 162. Additional openings are similar to openings 164a are provided at the top and bottom ends thereof for securing the end caps to the top and bottom sections 163. Openings 164a are aligned with the openings 162e.
The mold material, which is preferably polyethylene, is inserted into the rotor casting mold assembly 160, which is mounted upon a suitable turntable, and rotated, typically at an angular velocity suitable to drive the mold material into the mold sections, thereby forming a pair of panels.
More particularly, polyethylene in powdered form is inserted into the tool. When the cover caps are securely fastened to the mold tool, the assembly is mounted upon a platform capable of rotating in three (3) mutually perpendicular directions.
The mold assembly is heated as it is spun.
- When a proper temperature is obtained for a suitable time period, the mold assembly is transferred to a cooling station where it is cooled as the mold continues to spin. When the mold is cooled for a sufficient period, it is sent to a stripping station where the liner sections are removed. The process is the same for each of the liner members of the manhole sections with the only exception being that the mold obviously differ for different sections.
In addition, although Fig. 1 discloses a manhole assembly with a slab top and a liner therefor when desired, a cone-shaped top can be substituted therefor and liner sections to line the interior of a cone-shaped top may also be produced using the rotocast method.
Each panel represents one-third of the circumference of a manhole section to be cast. The mold sections 162 are of a suitable height. The ribs or returns are spaced at six inch centers enabling the panels to be cut down to the desired height.
As was described hereinabove, the returns along the vertical sides of the liner sections cooperate to form a substantially T-shaped configuration when the panels are positioned side-by-side, enabling the C-shaped clip to be driven over the top of the T-shaped arrangement, to provide an effective seal.
The non-corrosive ties, preferably nylon tie members, which are looped through the reinforcing ribs at about the wire reinforcement significantly increase the liner's ability to withstand pull-out or loss of shape due to hydrostatic pressure, the anchoring strength resulting from the solid cross-section of the rotor cast ribs.
The employment of low density liner polyethylene as the molding material provides the Sliners with excellent abrasion and chemical resistance, high impact resistance, and the ability - to withstand a multitude of welding methods to fabricate custom designs, fasten appurtenances thereto and/or facilitate field repairs.
10The uniform size liner sections, which require separate molding means for manhole sections of each standard diameter may be mass produced, and conveniently stored in a compact manner for use either in-situ casting in new construction or 15rehabilitation of existing underground structures, the design herein elim;n~ting the need for custom fabrication on a job site.
Claims (20)
1. A liner assembly for lining an annular-shaped interior of a cast structure to protect the cast structure from corrosion, said assembly comprising:
a plurality of liner sections, each section being comprised of a curved member having a convex surface engaging said cast structure and a concave surface defining an interior of said structure;
said member having a plurality of spaced substantially parallel curved reenforcing ribs integral with said member and extending into and embedded in said cast structure;
opposing sides of each member extending substantially parallel to a longitudinal axis of said annular-shaped interior and having integral flanges extending outwardly from said convex surface and into said cast member;
the flanges of each member being arranged in opposing fashion with the flanges of adjacent members forming said liner assembly;
resilient, compressible gasket means being arranged between the flanges of adjacent members;
said flanges having an increased thickness at the free ends thereof forming bulges on sides thereof opposite those sides engaging said gasket means;
an elongated C-shaped fastening clip joining the opposing bulges of said flanges for compressing said gasket therebetween to form a liquid-tight seal along said joint;
said gasket being an elongated strip of resilient compressible material having a substantially oblong cross-section, said strip extending an entire length of each joint defined by opposing flanges of adjacent liner section members;
and said liner assembly providing a liquid-tight seal about the annular interior of said cast member.
a plurality of liner sections, each section being comprised of a curved member having a convex surface engaging said cast structure and a concave surface defining an interior of said structure;
said member having a plurality of spaced substantially parallel curved reenforcing ribs integral with said member and extending into and embedded in said cast structure;
opposing sides of each member extending substantially parallel to a longitudinal axis of said annular-shaped interior and having integral flanges extending outwardly from said convex surface and into said cast member;
the flanges of each member being arranged in opposing fashion with the flanges of adjacent members forming said liner assembly;
resilient, compressible gasket means being arranged between the flanges of adjacent members;
said flanges having an increased thickness at the free ends thereof forming bulges on sides thereof opposite those sides engaging said gasket means;
an elongated C-shaped fastening clip joining the opposing bulges of said flanges for compressing said gasket therebetween to form a liquid-tight seal along said joint;
said gasket being an elongated strip of resilient compressible material having a substantially oblong cross-section, said strip extending an entire length of each joint defined by opposing flanges of adjacent liner section members;
and said liner assembly providing a liquid-tight seal about the annular interior of said cast member.
2. The liner assembly of claim 1 wherein the liner sections and the fastening clip are formed of a plastic material.
3. The liner assembly of claim 1 wherein said liner is formed of polyethylene.
4. The liner assembly of claim 1 wherein said fastening clip is formed of polyethylene.
5. The liner assembly of claim 1 wherein the fastening clip is formed of stainless steel.
6. The liner assembly of claim 2 wherein said liner is formed of low density polyethylene.
7. The apparatus of claim 1 wherein said gasket is formed of a suitable rubber or rubber-like material.
8. The apparatus of claim 7 wherein said material is EPDM.
9. The apparatus of claim 1 further comprising means joining the ribs to reenforcing means embedded in the cast material.
10. The apparatus of claim 1 wherein said cast member is formed of concrete.
11. The apparatus of claim 1 wherein said liner assembly is comprised of at least two liner sections of substantially equal size.
12. The apparatus of claim 1 wherein said liner assembly is comprised of three liner sections of substantially equal size.
13. A method for producing a manhole section provided with a corrosion-resistant liner assembly, comprising the steps of:
(a) providing a plurality of curved liner sections each having a concave surface which, when said liner sections are joined, define an interior surface of an annular assembly for lining said manhole section;
(b) providing vertically aligned integral flanges along each side of each liner section, said flanges being formed to having substantially flat gasket engaging surfaces and a bulge on an end of the flange and extending in a direction opposite said gasket engaging surface;
(c) arranging the flanges of adjacent liner sections in closely spaced opposing fashion;
(d) providing a gasket comprised of an elongated strip;
(e) positioning said gasket against the gasket engaging surfaces of flanges of adjacent liner sections;
(f) providing C-shaped elongated fastening means for joining said flanges engaging said gasket means for securing said adjacent liner sections to one another and compressing said gasket means an amount sufficient to create a corrosion-resistant liquid-tight seal in said joint;
(g) sliding said elongated fastening clip onto said flanges to effect a water-tight seal;
(h) assembling all of said liner sections to one another utilizing steps (c) though (g);
(i) casting a manhole section about said assembled liner sections to form a manhole section of generally cylindrical shape having an interior substantially cylindrical-shaped surface engaging the convex surfaces of said assembled liner sections;
(j) said flanges forming said joints extending into said cast material and being embedded therein.
(a) providing a plurality of curved liner sections each having a concave surface which, when said liner sections are joined, define an interior surface of an annular assembly for lining said manhole section;
(b) providing vertically aligned integral flanges along each side of each liner section, said flanges being formed to having substantially flat gasket engaging surfaces and a bulge on an end of the flange and extending in a direction opposite said gasket engaging surface;
(c) arranging the flanges of adjacent liner sections in closely spaced opposing fashion;
(d) providing a gasket comprised of an elongated strip;
(e) positioning said gasket against the gasket engaging surfaces of flanges of adjacent liner sections;
(f) providing C-shaped elongated fastening means for joining said flanges engaging said gasket means for securing said adjacent liner sections to one another and compressing said gasket means an amount sufficient to create a corrosion-resistant liquid-tight seal in said joint;
(g) sliding said elongated fastening clip onto said flanges to effect a water-tight seal;
(h) assembling all of said liner sections to one another utilizing steps (c) though (g);
(i) casting a manhole section about said assembled liner sections to form a manhole section of generally cylindrical shape having an interior substantially cylindrical-shaped surface engaging the convex surfaces of said assembled liner sections;
(j) said flanges forming said joints extending into said cast material and being embedded therein.
14. A method for producing a manhole section provided with a corrosion-resistant liner assembly, comprising the steps of:
(a) providing a plurality of curved liner sections each having a concave surface which, when said liner sections are joined, define an interior surface of an annular assembly for lining said manhole section;
(b) providing horizontally aligned integral curved supporting ribs at spaced intervals along a curved side of each liner section;
(c) providing an elongated gasket between adjacent liner sections and engaging flanges provided along vertical sides of the liner sections;
(d) joining flanges of adjacent liner sections by fastening clips to compress the gasket therebetween, providing a corrosion-resistant liquid-tight seal in said joint;
(e) providing an annular wire mesh cage surrounding said liner sections;
(f) providing openings in said supporting ribs;
(g) passing tie members about wires of said cage and through said openings;
(h) tying ends of each tie member to anchor the liner sections to said cage; and (i) casting a manhole section about said assembled liner sections to form a manhole section of generally cylindrical shape having an interior substantially cylindrical-shaped surface engaging the convex surfaces of said assembled liner sections, said supporting ribs and said flanges forming said joints extending into said cast material and being embedded therein and said cage and ties being embedded therein to secure said clips to the cast member.
(a) providing a plurality of curved liner sections each having a concave surface which, when said liner sections are joined, define an interior surface of an annular assembly for lining said manhole section;
(b) providing horizontally aligned integral curved supporting ribs at spaced intervals along a curved side of each liner section;
(c) providing an elongated gasket between adjacent liner sections and engaging flanges provided along vertical sides of the liner sections;
(d) joining flanges of adjacent liner sections by fastening clips to compress the gasket therebetween, providing a corrosion-resistant liquid-tight seal in said joint;
(e) providing an annular wire mesh cage surrounding said liner sections;
(f) providing openings in said supporting ribs;
(g) passing tie members about wires of said cage and through said openings;
(h) tying ends of each tie member to anchor the liner sections to said cage; and (i) casting a manhole section about said assembled liner sections to form a manhole section of generally cylindrical shape having an interior substantially cylindrical-shaped surface engaging the convex surfaces of said assembled liner sections, said supporting ribs and said flanges forming said joints extending into said cast material and being embedded therein and said cage and ties being embedded therein to secure said clips to the cast member.
15. The method of claim 13 further comprising the steps of:
forming an opening in at least one of said liner sections;
providing a continuous toroidal-shaped gasket having a cross-section that includes a triangular-shaped main body portion, an integral substantially T-shaped head and an integral flange extending from one end of the body portion;
positioning the gasket in said opening by assembling a two-piece mandrel for supporting the gasket therebetween; and placing the flange over a marginal portion surrounding the opening in the liner section to provide a liquid seal therealong, whereby the T-shaped head is embedded in the cast material and an opening is provided in the cast material by said mandrel, the cast material opening being in communication with the opening in said liner section.
forming an opening in at least one of said liner sections;
providing a continuous toroidal-shaped gasket having a cross-section that includes a triangular-shaped main body portion, an integral substantially T-shaped head and an integral flange extending from one end of the body portion;
positioning the gasket in said opening by assembling a two-piece mandrel for supporting the gasket therebetween; and placing the flange over a marginal portion surrounding the opening in the liner section to provide a liquid seal therealong, whereby the T-shaped head is embedded in the cast material and an opening is provided in the cast material by said mandrel, the cast material opening being in communication with the opening in said liner section.
16. The method of claim 15 further comprising the step of disassembling and removing the mandrel when the cast material is set.
17. A cast member comprised of a continuous, substantially cylindrical wall;
an opening provided in said wall;
a liner lining an interior surface of said cylindrical wall and having an opening aligned with the wall opening;
a continuous, toroidal-shaped gasket formed of a resilient compressible material and having a cross-section comprised of a triangular-shaped main body portion and an integral, T-shaped head extending radially outward and being embedded in the cast material and an integral flange extending from one end of the main body portion and overlying a marginal portion of the liner surrounding the liner opening;
said main body portion having a plurality of continuous annular cavities each having an elongated, oblong cross-section and being oriented so that their longitudinal axes are substantially parallel to a surface of the main body portion which is diagonally aligned with a central axis of said liner opening to control collapsing of the main body portion as a pipe is inserted into the gasket by controlling the manner in which the resilient compressible material collapses the cavities in the region of the gasket which provides improved support of an inserted pipe.
an opening provided in said wall;
a liner lining an interior surface of said cylindrical wall and having an opening aligned with the wall opening;
a continuous, toroidal-shaped gasket formed of a resilient compressible material and having a cross-section comprised of a triangular-shaped main body portion and an integral, T-shaped head extending radially outward and being embedded in the cast material and an integral flange extending from one end of the main body portion and overlying a marginal portion of the liner surrounding the liner opening;
said main body portion having a plurality of continuous annular cavities each having an elongated, oblong cross-section and being oriented so that their longitudinal axes are substantially parallel to a surface of the main body portion which is diagonally aligned with a central axis of said liner opening to control collapsing of the main body portion as a pipe is inserted into the gasket by controlling the manner in which the resilient compressible material collapses the cavities in the region of the gasket which provides improved support of an inserted pipe.
18. The cast member of claim 17 wherein the gasket is formed of pdyisoprene.
19. The assembly of claim 1 wherein an annular wire mesh cage is positioned to surround said liner sections;
said liner sections having integral curved reenforcement ribs extending horizontally and projecting outwardly along a convex surface of each liner section and toward said cage;
a plurality tie members being looped through openings provided in the reenforcing ribs and encircling portions of wires forming the cage for anchoring said liner sections to said cage, said cage and said tie members and said reenforcement ribs being embedded in the cast material.
said liner sections having integral curved reenforcement ribs extending horizontally and projecting outwardly along a convex surface of each liner section and toward said cage;
a plurality tie members being looped through openings provided in the reenforcing ribs and encircling portions of wires forming the cage for anchoring said liner sections to said cage, said cage and said tie members and said reenforcement ribs being embedded in the cast material.
20. The assembly of claim 19 wherein said liner sections are formed of a rotocast method to provide integral reenforcement ribs which are substantially solid throughout their cross-section aid in maintaining the shape of the liner section.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US48034895A | 1995-06-07 | 1995-06-07 | |
| US08/480,348 | 1995-06-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2162357A1 true CA2162357A1 (en) | 1996-12-08 |
Family
ID=23907624
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2162357 Abandoned CA2162357A1 (en) | 1995-06-07 | 1995-11-07 | Method and apparatus for lining manhole assemblies and the like |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2162357A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102767230A (en) * | 2012-07-26 | 2012-11-07 | 宁夏大林科技有限公司 | Constituent component of inspection well body |
| CN108547323A (en) * | 2018-05-07 | 2018-09-18 | 安徽砼宇特构科技有限公司 | A kind of high intensity precast inspection well |
| CN112431287A (en) * | 2020-11-30 | 2021-03-02 | 湖北普耐姆塑业有限公司 | Combined plastic inspection well |
-
1995
- 1995-11-07 CA CA 2162357 patent/CA2162357A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102767230A (en) * | 2012-07-26 | 2012-11-07 | 宁夏大林科技有限公司 | Constituent component of inspection well body |
| CN102767230B (en) * | 2012-07-26 | 2015-07-29 | 宁夏大林科技有限公司 | Manhole well bore building block |
| CN108547323A (en) * | 2018-05-07 | 2018-09-18 | 安徽砼宇特构科技有限公司 | A kind of high intensity precast inspection well |
| CN112431287A (en) * | 2020-11-30 | 2021-03-02 | 湖北普耐姆塑业有限公司 | Combined plastic inspection well |
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