CA1195514A - Manhole construction - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Means and method for assuring tightly sealing a manhole/sewer pipe connection are provided herein. The heart of the invention resides in a molded elastomeric circular gasket for resiliently supporting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe. The transverse cross-section of the gasket has a generally triangular head, with a forward face pro-vided with an arcuate depressing therein, and a sloping rear face; a generally rectangular body, integral with the generally triangular head and generally "L" shaped leg depending from the body and coextensive with the rear face of the body, the leg of the "L" being directed towards the forward face. The method of installation of the gasket into the peri-pheral surface of an opening through the body of a manholw wall comprises the first step of installing at a predetermined movable location, between the inner and outer shells of a form for casting the concrete wall of a manhole, a special two-part mold. The two-part mold consists of an inner mold member of dished shaped having radially outwardly extending flanges thereon of greater diameter than the opening, and an outer mold member of complementary dished shaped having side flanges thereon of the same dia-meter as the opening. The mold is configured to hold a portion only of the elastomeric gasket strip, leaving a portion of the gasket strip pro-jecting outwardly from the mold. The second step involves positioning the mold between the shells by means of a depending bar held to the outer shell and temporarily but firmly secured to the outer shell. The next step involves pouring settable material into one space between the inner and outer shells so as to surround and enclose the mold, and so as to (abstract continued) surround and enclose those portions of the gasket strip which are not received within the mold. The settable material is then permitted to set, and the inner and outer forms are removed, the two part mold separated and removed. This leaves that portion of the gasket strip which had been embedded in the mold projecting into the opening in the body of the manhole wall.

Description

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This invention relates to the installation of sanitary sewers, and is particularly concerned with the problem of tightly sealing a man-hole against inflow or outflow of liquid, at the points where a sewer pipe passes through its walls. The invention also relates to elastomeric gaskets for resiliently supporting and sealing the space between a pipe and the surrounding surface of an opening through which the pipe passes.
The invention also relates to a method and a means for installing a gasket in the peripheral wall of an opening in a manhole for sealing a pipe passing through such opening. This invention also relates to an apparatus for supporting a rubber sealing ring or gasket in position while a concrete structure is cast thereabout, the apparatus serving the deEine an opening in the concrete structure and to support the rubber-sea]ing ring in posi~
tion while the concrete is formed thereabout in securing relation. This invention also relates to an apparatus and method for use in the formation of manholes. In particular, the invention is also concerned with the pro-duction of precast manhole bases.
The construction of concrete manholes is hea~ dirt~ work and the m~n who engage in this t~pe ~f w~rk are usually classified as unskilled labour, the use of the pre-cast base having a pipe section precast therein and pre-sealed thereto have also been proposed heretofore. Such pre-sealed structures lack the flexibility needed to accommodate changes that are frequently dictated by conditions encountered in the field and which are not known at the time the installation is in the design or planning s-tage.
Hence it is advantageous if a method that is devised for sealing the annu-lar opening between sewer pipes and concrete manholes is simple, inexpensive and easy to follow and use.
When forming openings in poured concrete structures it is necessary to permit ample time for the concrete to set to a relatively rigid - 1 - 5~

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condition, before the apparatus used to Eorm the opening in the concrete wall can be removed. Clearly, the longer the setting time, the more forms that must be used in order to enable the concrete objects to be produced on a mass production basis. Conversely, the shorter the curing time, the lower the capital investment that must be made in terms of forms, opening forming inserts, and the like. If the opening forming inserts are removed too soon, before the concrete is sufficiently set, the rubber gasket being set in the concrete opening may be jarred or moved prematurely, and con-sequently the water-tightness of the seal may be broken, Furtherrnore, in a heavy business like the concrete pouring business~ and concrete being a good fastening agent, it is frequently necessary to use a sledge hammer or some other heavy object to break loose an insert forming an opening in a concrete wall, These heavy removal techniques contribute to the proba-bility that the seal formed in place in the poured concrete will be jarred in a manner which breaks the water-tightness of the seal~
While it is important to keep the interior of a manhole reasonably dry, this has proved to be a difficult objective to accomplish where pipes pass through a manhole wall~ Concrete cannot economically be installed with precisely smooth surfaces. Gaskets and other seals are not always effec-tive in situations of the type. Too often water seeps past them, where irregularities, holes or humps are present in the concrete~
The sealing methods and seal constructions heretofore used are generally time consuming in application, and thus require that ample curing time be given to the concrete before forms can be removed. Long curing times for poured concrete, particularly in mass production situations, in-creases the cost of manufacture of the poured concrete forms. Furthermore~
complicated pouring techniques tend to increase the cost of -the poured concrete structures.

One proposed sealing technique has been the installation of 0-rings between suitably shaped collars which surround the pipe and mate with the inner surface of the opening through which the pipe passes. This has not been entirely successful, however, for minor imperfections in the concrete will permit the seepage of moisture past the 0~ring gasket.
Furthermore, such a gasket must be tight along at least two lines of con-tact,-and this doubles the problem of avoiding irregularities and rough-ness at any point which comes in contact with the 0~ring. Since the 0~
ring is solid, it is not easily forced into different shapes in order to conform to local irregularities in the surface or to imperfections in con~
centricity. Since the 0-ring can roll upon itself, it needs extraneous fittings to make it stay in place.
Because of the conditions under which sewer pipe is installed, it frequently happens that a section of pipe will lie at an angle to the overall axis of the pipe, due to subsidence in a muddy trench, lack of care in back filling, or any of numerous other causes~ When such a condition arises and affects a section of pipe which is to pass through the wall of a manhole, it is quite important that the opening through which the pipe passes should be so constructed as to allow for variations in alignment.
As noted hereinbefore, it has been proposed to use molded gaskets of elastomeric material and shaped like an ordinary washer. Such washers are embedded in concrete about their outer margin, and lie normal to the axis of the pipe. They are subject to the disadvantage that the elastomer used has lirnited stretch in radia].ly outward direction. That is, even though it can be made with an undersized hole~ so that the pipe will stretch the material on being inserted, the amount of stretch is not suf-icient, in the plane of the gasket, to provide enough freedom for dis-tortion to preserve a tight seal.

The shear stress imposed on sewer pipe passing through a manhole opening may be ~ery severe. Sometimes it is suEficiently substantial to break the pipe right off. If the load, including not only the weight of the pipe and its contents, but also that imposed by fill, traffic stress, and vibration, is great, the pipe will be driven down into the inner edge of the rubber in the lower part of the gasket, directly under the pipe, and the amount of compression may be sufficient to cause the top of the pipe to pull away from the inner upper edge of the gasket, thus leaving a small but opening between gasket and pipe. If the elasticity of the elastomeric material is sufficient to ensure that its upper rim will follow the pipe even under the stress conditions stated, it is probably so "tight" that insertion of the pipe is practically impossible. This fac-tor is important, for the choice of elastomeric material is limited. The ~STM specifications for rubber gasketed sewer pipe are quite strict. The elastomer usually conforms to ASTM 13, SBR 1200, or to ASTM 361, Poly-styrene, TS 2400.
If the embedded portions of the gasket are planar and extend in a normal direction away from the pipel they may be pulled right out of the concrete in which they are embedded, under stress of axial movement of the pipe.
~ne problem which faced the prior art was to provide an improved technique for positively and permanently anchoring the gasket in the ce-mentitious material which defines the inner surface of the opening. The problem did not appear to be solvable by the use of individually molded unitary gasket washers ["washers" as used herein, refers to centrally~
apertured articles of disk~like shape], since they lack sufficient resis-tance to compression in their lower, inner portion, which carries the major load, and were too subject to peripheral separation from the pipe in their upper portions. Furthermore, such washers would have to be stocked in many sizes.
~ s noted above, typical prior art structures include a sealing ring formed of rubber or rubber-like material which is inserted into the annular cavity formed in the usual pipe joint, whether this joint be formed between pipe sections or between the entry end of a second of pipe and the hole in a concrete manhole. Such prior art structures have not proven to ben entirely satisfactory from the standpoints of ease of in-stallations, durabili-ty and economy. On one such structure, a sealing ring inserted into the joint cavity is provided with two flanges which may be forced apart by means of an auxiliary sealing wedge. The friction of en-gagement between the sealing ring and the opposing walls of the annular cavity provide the holding power against dislodgement, but it has been found that pressure fluid internally of the pipes can blow out the seal or produce leakage. In another prior art structure, annular metal clamps are used to secure the sealing ring into the cavity; however, this has proven to be costly and time consuming in the manufacture and installations thereof.
Du~ch Patent 290,612 of Raatjes dated June 10, 1963 provided a ring-shaped sealing member of the detachable, flexible coupling being lo-cated at the radially outwards or inwards directed ring respectively of the recess, forming the inner or outer surface of the coupling part that com-prises the sealing me~ber and forming, at both sides of the recess, a strip whose diameter in the axial direction gradually decreased, beginning at the edge of the recess. The cross-sectional pattern of the anchoriny member of the molded washer shown therein seemed to be likely to remain embedded in its surrounding concrete, no matter how severe the stress upon it might become. But there seemed to be no way to convert a lineal extrusion having this cross-sectional shape into a disk-like washer, and no practical way to provide the endless cavity unless it could be formed by extrusion. Thus, this Netherlands Patent merely illustrated a gasket in the shape of a washer, having a corrugated face and having a rim embedded in concrete.
Pressure of the pipe entering the washer distorted the latter, and effected a seal between pipe and opening. Unfortunately, if the material of which the gasket is composed was too stiff, it would not permit easy insertion of the pipe, or, if not stiff enough, it would permit tiny spaces to open up, under the stress of traffic shocks, through which water could flow.
Several other proposals have made in the past in Canadian Patent No. 964,043, issued March 11, 1975, to Harry ~. Skinner, disclosed an apparatus adapted to support a rubber-sealing ring or gasket in posi-tion while a concrete structure is cast thereabout, the apparatus serving to define an opening in the concrete structure and to support the rubber-seal-ing ring in position while the concrete was formed thereabout in securing relation. The rubbex seal was an elaborate and expensive genexally V~shaped rubber sealing ring, which fitted between the circular opening in the man-hole and the pipe penetrating into the interior of the manhole. The sealing qualities of the rubber seal were said to be enhanced by applying outward pressure on the arms of the V-shaped seal by driving a wedge-shaped material into the space existing between the arms of the V~shaped seal. This system was relatively successful but the V-shaped seal was prone to ripping or tearing when the pipe is introduced into the interior of -the manhole.
Canadian Patent No. 971,997, granted July 29, 1975, to John Ditcher, provided a method for installing a sealing member which yieldingly spans the annular space between the exterior surface of a sewer pipe when it passed through theopening in the wall of a manhole, and the inner surface of the opening through which the pipe passed Ditcher disclosed an A-shaped sealing ring, of a particular specified cross-sections. This A-shaped seal performed reasonably well but was prone to breaking because of its hollow-core construction. Further, the two legs of the A-shaped seal were rather widely angled, and this construction, when the A shaped seal was distorted by inserting the pipe through the opening in the manhole, tended to place considerable lateral and upward pressure on the two legs of the seal, with the result that one or both of the two legs broke free from the concrete in which the legs are embedded.
The invention provided in Canadian Patent 971,997, issued July 29, 1975 to John Ditcher provided a method for installing a sealing element for use between the outer surface of a pipe and an opening in a wall through which the pipe passes. The method included casting a wall of settable material about a particularly described shaping member. The shaping member was provided with means defining a peripheral channel to engage a peripheral gasket ring of resilient material and to house a subs-tantial portion only of the ring. A remaining portion of the ring was leEt extending into the set-table material as it is being emplaced. The material was allowed to set and thereafter the shaping member was removed. This was said to provide a sealing member within the manhole opening.
The invention in Canadian Patent 996,150 issued Aug. 13, 1976 to John Ditcher provided a gasket for sealing the space between a pipe and the surrounding surface of an opening through which the pipe passed. The gasket was composed of elastomeric material, having, throughout its extend~ a uni-form cross-section. The gasket is made from an extruded rubber strip, hav-ing a cross section in the shape of a capital A. When properly positioned in the manhole opening, the apex of the A was exposed~ and extended radially inwardly to make first contact with the surface of the pipe. The legs of the A extended outwardly, and were embedded in cementitious material which lined the opening in the manhole wall. There was some difficulty in in-stallation because the elastomeric gasket was made from an extrusion in the cross-sectional form of a capital A, and hence it required some distortion of the gasket, to fit this gasket onto the mold rings.
Canadian Patent No. 1,018,331, issued October 4, 1977, to Ronald E. Yoakum, disclosed a means of automatically affecting a seal at the junc-tures between a manhole and its inlet and/or outlet sewer pipe connections by the use of a seal. It also taught a method of installing the seal.
A complex shaped elastomeric annular sealing means was positioned circum ferentially within the opening in the manhole, was intricately connected to the wall portion of the manhole and was adapted for automatically engaging the sewer pipe which was inserted through the manhole opening. The seal provided a connection which was purportedly water proof. The Yoakum seal was rather complex in construction and hence both expensive and difficult to install. The construction of the seal involved a number of grooves and projections, and hence because of the nature of poured concrete which does not flow readily into small corners and openings, it was difficult to ob-tain a water-tight seal, par-ticularl~ when the dry casting technique of pouring concrete was used.
The invention in Canadian Patent 1,073,938 issued Aug. 18, 1980 to John Ditcher provided a molded elastomeric gasket for resiliently sup-por-ting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe. The gasket had an outer cylindrical flange member connected to a main bulbous body portion by a composite inwardly directed annular web and an outwardly directed annular web. The main body portion was intetrally connected to region of the inner surface o- the cylindrical flange member and inteyral a "T"
cross-section head which was to be embedded in the materi.al lining the manhole opening.
The invention in Canadian Patent 1,077,692 issued May 2Q, 1980 to John Ditcher was based on the discovery that a seal having all of the desired properties could be made by utilizing an extrusion having a pipe-contacting part which, instead of being of A-shape was pear-shape in sec-tion and was unitarily provided with a T-shaped anchoring part, the stem of the T being united with the bottom of the pear-shaped part and affording, when longitudinally considered, a web of substantial height and th.ickness.
Such an extrusion can be used effectively only if handled in the complex manner specifically set forth.
The invention in Canadian Patent 1,079,993 issued June 2~, 1980 to Dominique Palazzo provided a sealing system, and a method of installation therefor, whereby the annular opening existing between an opening through the wall of a concrete manhole, and the inlet~outlet connection of the sewer pipe or conduit could be effectively and inexpensively sealed in a water-tight manner, to eliminate infiltration andfor ex-filtration of liquids into and out of the manhole. The seal is provided was said to be of sufficient flexibility in construction and design that it would be capable of continuing to maintain a water-tight seal between the manhole and the conduit, even when the manhole-conduit combination is subjected to significant degrees of distortion due to shifting earth, and relative mis-alignment occurs between the manhole opening and the conduit. The anchoriny legs were subject to stress and strain, and, even though they were firmly embedded i.n the concrete, were subject to breakage at theix flexive points, thus being prone to leakage.

The invention in Canadian Pa-tent 1,112,468 issued Nov. 17, 1981 to ~. Poulette provided a method for installing a~gasket in the peripheral wall of an opening in a masonry wall a particularly complicated series of steps using special complicated apparatus. The installing step required a high degree of expertise and adjustments for deficient sizes was difficult Typical seals were also disclosed in U.S. Patent Nos. 2,924,~27

2,935,349; 3~348,850 and 3,382,438. Such annular seals were secured in place either by frictional contact with the walls defining the clearance or in the alternative by auxiliary clamping devices assembled to the pipe or to the concrete structure. Such sealing arrangements suffered from the disadvantage of being diEficult and time consuming to install as well as being subject to leakage or blowout~
Another example of such gasket is shown in U.S, Patent No~ 3, 832,438, issued August 27, 1974. That gasket consists generally of a peak portion which engages the pipe and a leg portion which is embedded in con-crete around the peripheral wall of the opening. In the above patent, the peak portion of the gasket is positioned in a recess formed between the mating edges of two oppositely tapered metal molds. The molds are mounted between the walls of a form and concrete is poured between the walls to embed the leg portion of the gasket in the peripheral wall of the opening when the concrete is set.
Another prior art gasket is embedded in the wall of the riser and projects inwardly of the opening through the riser to engage the outer surface of the intersecting feed pipe. The gasket is made of a resilient material which permits the gasket to yield and form a tight seal when the intersecting pipe is thrust into position.
The invention in U.S. Patent 3,727,876~ issued April 17, 1973 to L.R. Keyser provided a three-piece assembly for the installation of the ~s~

seal. The assembly includes inner and outer mold members, and a ring-shaped sustaining plate. Thus, this patent provided ap~aratus for forming a void through a molded wall during fabrication thereof and supporting a gasket for embedment in the wall about the void.
The invention in U.S. Patent 3,758,060, issued Sept~ 11, 1973 to H.W. Skinner et al provided an apparatus for forming a pipe ]oint sealing device which serves the dual purpose of supporting a rubber-sealing ring in position while concrete was cast thereabout and also for defining the opening into which the sealing ring is installed. This mold device included plug structure of particular specification. ~lere, too, the major problem was of easy adjustability. This patent suffered the de-iciency that ad-justments for different locations of the manhole openings were difficult.
The invention in ~.S. Patent 3,759,285, issued Sept. 18, 1973 to R.E. Yoakum provided an in situ seal in a hole in the wall of a manhole which was said to permit independent movement of ei-ther the pipes or the base to maintain the seal and yet to accommodate changing job conditions.
However, because of the embedment means within the coverete, the seal could be worked lose and hence cause leakage.
The invention in U.S. Patent 3,787,061,issued ~an. 22, 1974 to R.E. Yoakum provided an in situ seal in a hole in the wall of a manhole in which the pipe engaging portion was a pair of spaced apart ribs, releasably biased inwardly but adapted to be flattened into sealing engagement with the pipe. Such flattening did not always, however, provide a continuous water-tight seal or movement or misalignment of the pipe or manhole~
In the invention in ~.S. Patent 3,874,068, issued April 1, 1975 to F.W. Skinner et al a pipe joint sealing device is provided which includes an annular resilient body of rubber-like material. This body is generally a V-shaped cross-section which includes radially inner and outer annular body portions or flanges which is secured to the hole in the wall of the man-hole by casting or molding concrete around the outer periphery or flange of the sealing ring such that when the concrete hardens, the ring is locked into position. A major deficiency is that, in order to effect a seal between the concrete manhole and the pipe a wedge of rubber material must be inserted into the space between the inner and outer flanges.
The invention in U.S. Patent 4,333,662 issued June 8, 1982 to William D. Jones provides a gasket which is particularly suited for seal-ing the annular space between a pipe and a port in an underground struc-ture is disclosed. The gasket comprises a hollow annular ring which sur-rounds the pipe and is connected by a narrow neck to a base at least partially embedded in the underground structure. The base has means ex-tending around its outer periphery to mount the seal securely in the manhole and to provide a block against water seepage across the periphery of the gasket.
The invention in U.S. Patent 4,387,900 issued June 14, 1983 to Jack Ditcher et al provides a resilient gasket having an outer annular flange positioned within a manhole opening and maintained thereagainst un-der compression by means of a compression band. The gasket is provided with a central opening defined by an enlarged beaded periphery having an elasticity adapted to tightly encircle the outer periphery of the pipe.
A folded intermediate section is arranged between and integrally ~oined to the outer flange and the beaded inner periphery, the intermediate sec-tion is comprised of first and second diagonally aligned annular portions integrally joined along a fold to define a V shape which imparts a yielda-bility enabling the gasket to maintain a watertight seal between the man-hole opening and the pipe, even in the presence of a significant misalign-ment therebetween. A strap is positioned about the intermediate section of the gasket adjacent the inner beaded periphery to enhance the water-tight seal between the gasket and the pipe. The compression band may be provided with pairs of substantially V--shaped slots which enable the band to assume a curvature in a direction transverse to the curved periphery in order to conform to the curvature of the manhole opening. The clamping band is formed of a material which is impervious to the surrounding envir-onment and has a gap and a segment hingedly connected to the main bodythereof for placement in the gap and against the interior surface oE the gasket to lock the compression band in position and maintain the gasket flange under compression. An expansion assembly includes an expansion ring which cooperates with a hydraulic jack and is positioned against the com-pression band to expand the compression band into position against the gasket flange and to apply a force uniformly around the compression band to insure proper positioning and locking of the clamping band.
While each of the above disclosed patented devices may function satisfactorily for its intended purpose, none has all of the att~ibutes of a commercially desirable seal. For instance, such a seal should pro~
vide leak resistance up to 10 psi. and should enable the pipe to be de-flected omnldirectionally up to 20~ with respect to its receiving port.
A satisfactory pipe seal should also prevent the pipe from contacting the bottom of the pipe-receiving port in response to transverse shear loads on the pipe as may be imposed by backfill and traffic loads adjacent the man-~hole. The seal should also be sufficiently compressible as to accommodate variations in the outside diameters of pipes of different materials which ~ 13 have the same nominal inside diameters. I~he seal should also be mounted securely in place and should be capable of in-field adjustments and repair to accommodate unusual situations. A desirable seal must also be suffici~
ently foolproof as to be capable of being installed by relatively unskilled labor, and the seal must be capable of being installed rapidly and in a minimum amount of time.
In spite of all the aforementioned prior art there is still a need for an arrangement and method for joining the ends of burried pipe to a manhole wherein precise location of the manhole is not required, and whereby a joint can be easily and quickly made. It is also desirable that a seal be effected automatically when a pipe is inserted into an opening in the wall of a manhole, and that such seal be maintained upon the occurrence of universal relative movements of either the manhole or the pipeline.

It is an object of an aspect of the present invention to provide a method for installing a sealing member which yieldingly spans the space betwen a sewer pipe which passes through the wall of a manhole and the inner surface of the opening through which the pipe passes.
It is an object of another aspect of the invention to provide shaping elements which will impart the desired configuration to the opening through which the pipe passes, which can be readily installed at the time the manhole is being cast, and whose location can be readily controlled at will, and which can readily removed after the concrete sets.
It is an object of yet another aspect of the invention to con-figure shaping elements in such a way as to enable them to receive and secure, ly hold in place an elastomeric gasket whiah surrounds the entire periphery of the opening and which will hold that gasket element in its intended position with portions thereof extending outwardly from the shaping element to be embedded in the concxete as the manhole is poured.
It is an object of still another aspect of the invention to provide a gasket which can be readily be formed by the extrusion of an elas-tomeric material, and which, as formed, is readily deformable so that it may locally yield to accommodate itself to irregularities in surface or in concentricity as it yieldingly spans the distnace between a sewer pipe and the surface of the opening through which the pipe passes.
An object of a still further aspect of the present invention is to provide means automatically effecting a seal at the juncture between a manhole and its inlet and/or outlet pipe connections when a pipe is inserted therein and for maintaining the effectiveness of the seal during and after the occurrence of universal relative movement of either the manhole struc-ture or the pipe structure.
It is an object of another aspect of the present invention to provide a new method and apparatus for installing a gasket in the peripheral wall of an opening in a masonry wall.
It is an object of another aspect of this invention to provide a combination gasket-supporting and concrete-molding device so arranged that upon positioning the same in a concrete mold, a concrete structure may be cast with the hole being formed by the device and a sealing ring or gasket permanently interlocked into the perimeter of the opening.
It is an object of still another aspect of this invention to pro-vide an apparatus for forming the opening in a concrete structure and mount-ing a rubber-sealing ring in relation thereto, the device being constructed such that once the concrete hardens it may be simply and quickly removed therefrom.
It an object of yet another aspect of this invention to provide - 15 ~

a pipe joint sealing device which permits some relative movement between a section of pipe and another structure to which it is jointed without causing failure of the seal or damage to the pipe.
An object of another aspect is to provide a manhole joint arrangement that can be pre-manufactured and which then requires no tools to install on site.
An object of a further aspect is to provide a manhole joint arrangement that allows for variations to occur in the relative positions of the manhole and the pipe connected thereto.
By one broad aspect of this invention, an apparatus is provided for installing a gasket having a pipe-engaging portion and anchoring por-tion in the peripheral wall of an opening in a masonary wall, comprising:
(a) an inner mold member of dished shaped having radially outwardly ex-tending flanges thereon of greater diameter than the opening; (b) an outer mold member of complementary dished shaped having side flanges thereon of the same diameter as the opening; (c) means between the outer periphery of a flange on the outer mold member and a flange on the inner mold mem-ber adopted to recieve the pipe engaging portion of the gasket and to allow the anchoring portion of the gasket to project radially outwardly;
and (d) means for temporarily but firmly securing the inner mold to the outer mold.
By another aspect of this invention, a forming apparatus for usw in installing in place a sealing ring in the peripheral surface of a circular opening through a wall formed from a settable material comprising:
(a) an inner mold member of dished shaped having radially outwardly ex-tending flanges thereon of greater diameter than the opening; (b) an outer mo].d member of complementary dished shaped having side Elanges there-on oE the same diameter as the opening; (c) rneans between the outer peri-phery of a flange on the outer mold member and a flange on the inner mold member adapted to receive the pipe-engaging portion of the gasket and to allow the anchoring portion of the gasket to project radially outwardly;
and (d) means for temporarily but firmly securing the inner mold to the outer mold and to the outer shell designed to form the peripheral surface.
By still another aspect of this invention, a me-thod is provided for installiny a gasket having a pipe-engaging portion and an anchoring portion in the peripheral wall of an opening in a poured-in-place masonry wall, comprising : (i) erecting a form including an inner wall and an outer wall to define the poured-in-place masonry wall; (ii) providing an assembly of (a) an inner mold member of dished shaped having radially outwardly ex-tending flanges thereon of greater diameter than the opening; (b) an outer mold member of complementary dished shaped having side flanges thereon of the same diameter as the opening; and (c) a gasket having a pipe engaging portion and an anchoring portion disposed in means between the outer periphery of a flange on the outer mold member and a flange on the inner mold member adapted to receive the pipe-engaging portion of the gasket and to allow the anchoring portion of the gasket to project radially outwardly;
(iii) suspending the assembly at a desired preconceived location between the ilmer and outer walls of the form by a depending bar having spaced apart means thereon to be joined temporarily but firmly to cooperating means on the assembly; (iv) in filling the space between the walls o:E the form with settable material, so as to embed the anchoring portion of the gasket in the settable material; and (v) after setting of the material, 17 _ s~

removing -the form, ~le inner mold member and the outer mold member so as to leave the pipe~engaging porti~n of the gasket is not embedded in the set material projecting into the space intended to receive the pipe.
By a still furtiler aspect of this invention, a m~lded elasto-meric circular gasket is provided for resiliently supporting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe, the transverse cross-section of the gasket having: (a) a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face; (b) a gen-erally rectangular body, integral with the generally triangular head; and (c) a generally "L" shaped leg depending from the body, and coextensive with the rear face of the body.
By a further aspect of this invention, a method is provided for sealing the space between a pipe and an opening in a wall through which the pipe passes, which method comprises (i) providing a molded elastomeric circular gasket for resiliently supporting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe, the transverse cross-section of the gasket hav-ing^ (a) a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face; (b) a generally rectangular body, integral with the generally triangular head; and (d) a generally "L" shaped leg depending from the body, and coextensive with the rear face of the body; (ii) posi-tioning and supporting the gasket so that it is located between wall~defining surfaces with its central axis being general].y perpendicular to the plane of the wall and with its "L"-shaped leg extending radially outwardly; (iii) filling the wall space surrounding the gasket with suficient settable material to fill the space and embed the entire "L"-shaped leg in the settable material; and (iv) allowing -the settable material to set.
By another aspect of this invention, there is provided for use in forming a fluid-tight seal between a pipe and a wall opening through which the pipe passes, a molded elastomeric circular gasket for resilient-ly supporting a sewer pipe in a manhole opening and sealing the space be-tween the wall of the opening and the surface of the pipe, the transverse cross-section of the gasket having: (a) a generally triangular head, hav-ing a forward face provided with an arcuate depressing therein, and a sloping rear face; (b) a generally rectangular body, integral with the generally triangular head; and (c) a generally l'L" shaped leg depending from the body, and coextensive with the rear face of the body.
By yet another aspect of this invention, there is provided, for use in forming a fluid-tight seal between a pipe and a wall opening through which the pipe passes, the combination of a mass of settable material externally configured to provide the wall opening and a molded elastomeric circular gasket for resiliently supporting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe, the transverse cross-section of the gasket having:
~a? a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face; (b) a generally rec~
tangular body, integral with the generally triangular head; and (c) a generally "L" shaped leg depending from the body, and coextensive with the rear face of the body extending circumferentially about the opening in the mass with the entire "L" shaped leg being embedded in settable material with the head portion of the gasket protruding into the opening.

~5~

By another aspect of this invention, there is provided, in combination, a concrete manhole structure having a manhole opening through which a sewer pipe can pass and a molded elastomeric circular gasket for resiliently supporting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of -the pipe, the transverse cross-section of the gasket having: (a) a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face; (b) a generally rectangular body, in-tegral with the generally triangular head; and (c) a generally "L"
shaped leg depending from the body, and coextensive with the rear face of the body positioned between the inner and outer walls of the manhole and extending circumferentially about the wall opening with the entire "L"-shaped leg being embedded in the concrete surrounding the manhole opening and with the head portion of the gasket protruding into the manhole open-ing on the periphery thereof.
By a further aspect of this invention, a shaping element is provided to define the inner surface of an opening through a wall of settable material as it is being formedf the shaping element comprising:
inner and outer mating parts, releasably securable together and providing an inner peripheral wall configured to produce an inner surface to the opening of the desired size and shape, and an outer peripheral wall configured to produce an outer surface to the opening, each of the parts having a transverse flange extending from its periphery, and having means associated with the Elange to cooperate with the flange upon the other element, the flanges providing a periphera]. channel; and means associated with the inner portions of the inner and outer mating parts to secure both parts together.

~3 ~

By another aspect of this invention, there is provided in a device for establishing a watertight seal between the inner surface of an opening in a manhole wall and the outer surface of a sewer pipe passing through the opening, apparatus for positioning a peripheral gasket of elastomeric material in a locus within the concre-te of the manhole wall, the apparatus comprising: an outer shaping element having a peripheral wall structure of the shape desired for the outer portion of the opening through the wall and terminating in a flange; an inner shaping element having a peripheral wall adapted to complement the outer element in providing the desired shape for the finished opening, the wall terminating in an outwardly extending flange; the adjacent surfaces of the flanges of the inner and outer elements providing, between the opposing surfaces, a peripheral re-cess which configured to receive and support a portion of the gasket strip first mentionsa; the shaping elements being provided with releasable clamping means simultaneously to site the shaping elements at a predeter-mined location within the manhole wall thereby to site the opening, and to hold them together in use and impose a limited pressure on the gasket~
By yet another aspect of this invention, there is provided, in a method of installing a sealing element for use between the outer surfaces of a pipe and an opening in a masonry wall through which the pipe passes, which method comprising the steps of: casting a wall of settable material about a sectional shaping membsr sited at a predetermined movable location with respect to the masonry wall configured to produce an opening at the desired location and of the desired dimensions to pass the pipe in slight-ly spaced relation thereto; the shaping member being provided with means defining a peripheral channel configured to engage a peripheral gasket ring of resilient material and to house a substantial portion only of the ring, leaving a remaining portion extending into the settable material as it is being emplaced; permitting the material to set, and thereafter re-moving the shaping member.
By still another aspect of this invention a method is provided for installing a sealing element in the peripheral surface of an opening through the body of a manhole wall, wh:ich method comprises the steps of installing at a predetermined movable :Location, between the inner and outer shells of a form for casting the concrete wall of a manhole, a two-part mold, comprising: (a) an inner mold member of dished shaped having radially outwardly extending flanges thereon of greater diameter than the opening, (b) an outer mold member of complementary di.shed shaped having side flanges thereon of the same diameter as the opening; the mold being configured to hold a portion only of an elastomeric gasket strip, leaving other structure of the gasket strip projecting outwardly from the mold;
positioning the mold between the shells by means of a depending bar held to the outer shell and temporarily but firmly secured to and pouring settable material into the space between the inner and outer shells so as to surround and enclose the mold, and so as to surround and enclose those portions of the gasket strip which are not received within the mold; per-mitting the settable material to set, and then removi.ng the inner and outer forms and separating and removing the two parts of the mold, thus leaving that portion of the gasket strip which had been embedded in the mold projecting into the opening in the body of the manhole wall.
By yet another aspect of this invention, a method is provided for manufacturing a pre-cast portion of an access pit for underground piping systel~ comprising the steps of: assembling an annular elastomeric seal body on a mandrel, two part mandrel comprising: (a) an inner mold member of dished shaped having radially outwardly extending flanges thereon of greater diameter -than the opening; (b) an outer mold member of comple-mentary dished shaped having side flanges thereon of the same diameter as the opening; (c) means between the outer periphery of a flange on the outer mold member and a flange on the inner mold mernber adapted to re-ceive the pipe-engaging portion of the gasket and to allow the anchoring portion of the gasket to project radially outwardly; fixing the assembly to one of a pair o~ form members and positioned between the members by means of a depending bar held to the outer shell and temporarily but firmly secured to; pouring concrete between the form members and around the assembly; and removing the form mernbe~s and the mandrel after the con-crete has set.
As described above, the present invention involves, in one as-pect the concept of providlng a first support for the pipe, which support is sufficiently resilient to compensate for stress and for shear, is sufficiently flexible to accomodate extensive misalignment of the pipe, and yet is capable of affording an absolutely fluid tight seal in the rim of the opening. The gasket of an aspect of the present invention is easy to install, comparatively inexpensive to make, and extremely relia~
ble in use. The sealing system of an aspect of the invention utilizes a continuous profile having a generally triangular shaped head, including flat face portion provided with an inset arcuate depression, a sloping rear face, a flat base and flat rear wall extending downwardly to a for-wardly-facing "L"-shaped leg~ An effective water-tight seal is estab-lished when the pipe is inserted through the opening in the manhole be-cause the outer diameter of the pipe, being of greater diameter than the inner diameter of the sealing ring, causes the pipe to contact and distort the ruhber sealing ring such that the rubber sealing ring applies pressure to the external surface of the pipe, therehy providing a water-tight seal between sealing ring and the pipe.
The cylindrical ring is preferably positioned on the rim de-fined between the inner and outer mating dished mold rings so that its triangular shaped head is within the peripheral groove, and the "L"-shaped corresponding leg projecting outwardly. The complementary parts of10 the mold rings are clamped in place wi-th the inverted manhole hold and held therein by the adjustment securement clamping stavel.
A suitable mold ring according to an aspect of this invention for the installation of the novel gasket of an aspect of this invention consists of inner and outer shells oE dished shaped which are so configured that when assembled they define between them a peripheral groove which accommodates the triangular-shaped head, leaving the "L"-shaped leg free.
In aspects of the present invention, the inner and outer shells are pro-vided with complementary rectangular insets, provided with mating holes for adjustahle securement within the manhole mold by the adjustment se-curement clamping stave. Concrete or other cementitious~materiaI is then applied to mold the manhole and also to define the peripheral wall of the opening in the manhole wall. The cementitious material covers the llL-shaped leg" and embeds it, but the triangular;shaped head is exposed, and is adapted to yield to receive the pipe inserted therein, upon separa-tion and removal oE the mold parts.
One of the advantages of aspects of the present in~ention is the unexpected discovery that extrusions having the cross~section form described can often be used with pipes of different sizes, without alter-ing their cross-sectional dimensions. A11 that is necessary is to change the length of the extrusion and the diameter of the mold rings. This capacity to coact with pipe of many different sizes is believed to be due, in part at least, to the fact that the manner of use places considerable compression on the inner flattened face portion of the gasket, and causes tension on its outer, sloping periphery. As a consequence, the gasket of an aspect of the present invention hugs the pipe tightly.
It must be reali~ed that, in the past, the part of the gasket which lies at the bottom of the opening, when in use, had to sustain most of the load of the pipe and its contents, and in addition had to resist environmental stresses, which may be imposed upon the pipe outside of the manhole by the weight of the fill, or by impacts due to traEfic shock, or by the dead weight of passing vehicles. If the prisr art gasket were to be used, it could yield too much under these stresses, and become ovexly compressed at the bottom of the opening. The pipe could then pull away from the gasket at the upper part of the opening, thereby allowing fluid to pass the seal. Since the stresses imposed may some~
times be measured in thousands of pounds, particularly where the pipe i5 large - say 24" or 30" in diameter, it was thought to be necessary to em-ploy a molded gasket ring which would manifest both sufficient resis~
tance to compression at the bottom of the opening and sufficient capaci-ty for expansion at the top.
The gasket of an aspect of this invention described herein is remarkably adapted to meet this problem~ It cooperates with a xim on the interior of the hole in the manhole to support such considerable weight without the need for a large mass of elastomeric material to be present to carry the weight imposed, Moreover, the flattened gasket pro-vides an extensive rubbery seal between the pipe and the hole.
The other major need is to ensure that the gasket ring is so firmly anchored in the concrete as to resist any stress which might tend to dislodge it. This is ensured by the deep embedding of the "L-shaped"
leg, as well as by the embedding of the base of the body in the surround-ing concrete~

The concrete material used in casting the manhole will usually be a fairly stiff mix. Therefore, the forms can be stripped from the freshly cast pipe fairly soon after casting. This permits a minimum number of forms to be used in the operation and appreciably reduces the capital expenditures which would otherwise be necessary if the forms were retained about the pipe until they had cured.
By the same token it is desirable that the mold members may also be removed from the freshly cast pipe at the same time the pipe form is removed so that the mold members may also be reused and the number necessary kept to a minimum. However, as noted above, it is important that the gasket be shaped and positioned properly with respect to the hole in the wall of the manhole.
While the freshly cast concrete is capable of sustaining its own weight, some support must be provided for the resilient gasket to insure that it remains around and positioned correctly in the riser wall until the concrete has cured to a degree sufficient to retain the gasket in place. At the same time, as noted above, it is desirable that the relatively expensive, void defining mold members, which also support the gasket during the cas-ting operation, be removed at the time the form is stripped from the riser for reuse.
In the accompanying drawings, Fig. l is a perspective view of the manhole with a sewer pipe installed therein according to one embodiment of this invention;
Fig. 2 is a cross-section through line II~II of Fig. li Fig. 3 is a perspective view of the gasket of an embodiment of this invention;

Fig. 4 is a transverse cross~section of the gasket of Fig. 3 embedded in the concrete of the manhole around the hole;
Flg, 5 is an e~ploded side elevational view of the two part mold of an emb~diment of this invention for the installation of the gas-ket in the hole in the manhole;
Fig. 6 is a horizontal cross-sectional view of the two;part mold of Fig. 5 in installed attitude; and Fig. 7 is a horizontal cross-sectional view of the hole in the manhole after removal of the two~part mold, As seen in Figure 1 the manhole lO is a precast cylindrical member 11 with a concrete sewer pipe 12 extending through an opening 13 therein.
The opening 13 is provided with a cast~in~situ gasket 14, shown in greater detai] in Figures 3 and 4. The gasket is a cast)elongated rubber gasket formed into an endless circular form It consists of a head portion 15 including a front face 16 and a rear faca 17. Front face 16 includes an upper deflectable flange 18, an arcuate inset l9 and a lower, embedable portion 20. The rear face 17 is shorter than the 27 ~

front face 16 and is~joined thereto by a sloping face 21.
The rear face 17 extends downwardly to a leg 22 which is gen-erally of "L"~shaped i.e. in the form of a downward extension 23 and a forward-acing foot 24, defining a recessed zone 25 therebetween.
As seen in Figure 6 and 7, the manhole 10 is cast with the hole 13 therein and with the gasket 14 cast-in-situ by means of a manhole form including inner and outer cylindrical walls 25, 26 and a pair of com~
plementary mold rings 27, 28. m e inner mold ring 27 incl~ldes a main dished central circular area 30, having an annular rim 31 coextensive therewith. A reduction rectangu]ar flange 32 in the fotm of a radially inwardly extending portion 33 and an annular rim portion 34 leads to an expansion flange 35, terminating in a dished terminal rim 36.
Outer mold xing 28 includes a main central dished area 40 mat-ing with dished portion 30 and annular rim 31 and a stepped portion 41 mating with portion 33. Stepped portion 41 enlarges to an expansion flange 42 which continues as an intermediate rim 43 and an outer rim 44 terminating in a facia 45~
Before the assembled inner and outer mold rings 27, 28 are placed within the manhole form, the gasket 14 is placed thereon, with face 16 of the gasket abutting face 34 of inner form, and s]oping face 21 abutting expansion flange 42. In this way only face 16 and sloping face 21 are adapted to be exposed, with the removal~ of the gasket 14 being adapted to be embedded in the concrete.
In its installation in the manhole form, the two-part mold rings 27, 28 are assembled with their mating rectangular insets 46, 47 respectively together and with the gasket 14 therearound as described above. The mold ring unit is - -then suspended in -the inverted manhole form by means of rec-tangular fixing bar 48 which has an upper crown 48a and a depending f]ange 48b and which is provided with spaced apar-t apertures 49 to align with apertures 50a, 50b, in the insets 47, 46, respectively. A set screw 48c holds the bar 48 to the outer shell ~6 ~See Fig. 6). When ~he mold ring assembly is at the predetermined position in the manhole mold to provide aperture 13 at the preselected location, bolts 51 are passed through washers 51a, apertures 49, and 50a and 50b, and through washer 51b, and are held thereon by nuts 52.
Then the concrete is poured into the manhole form and when set, the forms and the mold rings are removed to provide a manhole with an aperture therein having a gasket molded in-situ.
The unique cooperation of the manhole opening 13 and the gasket 14 in maintaining a seal when sewer pipe 12 is inserted as shown in Figure 2. ~ere is is seen that the weight oE the sewer pipe 12 forces the head 15 of the gasket into its fully compressed position. However excess com-pression is prevented by contact of the sewer pipe 12 at 60 with flattened annulus 61 of the opening 13 where the base 62 of the sloping face 21 in~
tersects the lo~Jer portion of the manhole opening 13. Sealing contact is maintained because of the amount of contact between areas 63 of the sewer pipe 13 and 64 of the gasket 14.

This compression does not result in any transfer of forces to the leg 22, since the forces are absorbed by the compression of the upper portion 18 of the front face 16 into the arcuate depression 18.
Moreover, the lower portion 20 of the fron-t face is encased by the con-crete. Thus, the lower portion of the head of the gasket and the entire leg 22 are free from forces which might tend to loosen the gasket from within the concrete.

Claims (13)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An apparatus for installing a gasket having a pipe-engag-ing portion and anchoring portion in the peripheral wall of an opening in a masonry wall, comprising:
(a) an inner mold member of dished shaped having radially outwardly extending flanges thereon of greater diameter than said opening;
(b) an outer mold member of complementary dished shaped having side flanges thereon of the same diameter as said opening;
(c) means between the outer periphery of a flange on said outer mold member and a flange on the inner mold mem-ber adapted to receive the pipe-engaging portion of said gasket and to allow the anchoring portion of said gas-ket to project radially outwardly;
and (d) means for temporarily but firmly securing said inner mold to said outer mold.

2. A forming apparatus for use in installing in place a seal-ing ring in the peripheral surface of a circular opening through a wall formed from a settable material comprising:
(a) an inner mold member of dished shaped having radially outwardly extending flanges thereon of greater diameter than said opening;
(b) an outer mold member of complementary dished shaped having side flanges thereon of the same diameter as said opening;
(c) means between the outer periphery of a flange on said outer mold member and a flange on the inner mold mem-ber adapted to receive the pipe-engaging portion of said gasket and to allow the anchoring portion of said gasket to project radially outwardly;
and (d) means for temporarily but firmly securing said inner mold to said outer mold,.

3. A method of installing a gasket having a pipe-engaging portion and an anchoring portion in the peripheral wall of an opening in a poured-in-place masonry wall, comprising:
(i) erecting a form including an inner wall and an outer wall to define said poured-in place masonry wall (ii) .providing an assembly of (a) an inner mold member of dished shaped having radially outwardly extending flanges thereon of greater diameter than said opening;
(b) an outer mold member of complementary dished shaped having side flanges thereon of the same diameter as said opening;
and (c) a gasket having a pipe engaging portion and an anchoring portion disposed in means between the outer periphery of a flange on said outer mold member and a flange on the inner mold member adapted to receive the pipe-engaging portion of said gasket and to allow the anchoring portion of said gasket to project radially outwardly;
(iii) suspending said assembly at a desired preconceived location between said inner and outer walls of said form by a depending bar having spaced apart means thereon to be joined temporarily but firmly to coopera-ting means on said assembly;
(iv) in filling the space between the walls of the form with settable material, so as to embed the anchoring portion of the gasket in said settable material;
and (v) after setting of said material, removing the form, the inner mold member and the outer mold member so as to leave the pipe-engaging portion of said gasket is not embedded in the set material projecting into the space intended to receive the pipe.

4. A molded elastomeric circular gasket for resiliently sup-porting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe, the transverse cross-section of said gasket having:
(a) a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face;
(b) a generally rectangular body, integral with said generally triangular head;
and (c) a generally "L" shaped leg depending from said body, and coextensive with the rear face of said body.

5. The method of sealing the space between a pipe and an opening in a wall through which the pipe passes, which method comprises (i) providing a molded elastomeric circular gasket for resiliently supporting a sewer pipe in a manhole open-ing and sealing the space between the wall of the opening and the surface of the pipe, the transverse cross-section of said gasket having:
(a) a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face;
(b) a generally rectangular body, integral with said generally triangular head;
and (c) a generally "L" shaped leg depending from said body, and coextensive with the rear face of said body;
(ii) positioning and supporting said gasket so that it is located between wall-defining surfaces with its central axis being generally perpendicular to the plane of the wall and with its "L"-shaped leg extending radially outwardly;
(iii) filling the wall space surrounding the gasket with suf-ficient settable material to fill said space and embed the entire "L"-shaped leg in the settable material;
and (iv) allowing the settable material to set.

6. For use in forming a fluid-tight seal between a pipe and a wall opening through which said pipe passes, a molded elastomeric circular gasket for resiliently supporting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe, the transverse cross-section of said gasket having:
(a) a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face;
(b) a generally rectangular body, integral with said generally triangular head;
and (c) a generally "L" shaped leg depending from said body, and coextensive with the rear face of said body.

7. For use in forming a fluid-tight seal between a pipe and a wall opening through which said pipe passes, the combination of a mass of settable material externally configured to provide said wall opening and a molded elastomeric circular gasket for resiliently supporting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe, the transverse cross-section of said gasket having:
(a) a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face;
(b) a generally rectangular body, integral with said generally triangular head;
and (c) a generally "L" shaped leg depending from said body, and coextensive with the rear face of said body extending circumferentially about the opening in said mass with the entire "L"-shaped leg being embedded in settable material and with the head portion of the gasket protruding into the opening.

8. In combination, a concrete manhole structure having a wall opening through which a sewer pipe can pass and a molded elastomeric circular gasket for resiliently supporting a sewer pipe in a manhole opening and sealing the space between the wall of the opening and the surface of the pipe, the transverse cross-section of said gasket having:
(a) a generally triangular head, having a forward face provided with an arcuate depressing therein, and a sloping rear face;
(b) a generally rectangular body, integral with said generally triangular head;
and (c) a generally "L" shaped leg depending from said body, and coextensive with the rear face of said body positioned between the inner and outer walls of the manhole and extend-ing circumferentially about the wall opening with the entire "L"-shaped leg being embedded in the concrete surrounding the manhole opening and with the head portion of the gasket protruding into the manhole opening on the periphery thereof.

9. A shaping element to define the inner surface of an open-ing through a wall of settable material as it is being formed, said shaping element comprising: inner and outer mating parts, releasably se-curable together and providing an inner peripheral wall configured to produce an inner surface to said opening of the desired size and shape, and an outer peripheral wall configured to produce an outer surface to said opening, each of said parts having a transverse flange extending from its periphery, and having means associated with said flange to cooperate with the flange upon the other element, said flanges providing a peripheral channel; and means associated with the inner portions of said inner and outer mating parts to secure both parts together.

10. In a device for establishing a watertight seal between the inner surface of an opening in a manhole wall and the outer surface of a sewer pipe passing through said opening, apparatus for positioning a peripheral gasket of elastomeric material in a locus within the concrete of the manhole wall, said apparatus comprising: an outer shaping element having a peripheral wall structure of the shape desired for the outer portion of the opening through said wall and terminating in a flange; an inner shaping element having a peripheral wall adapted to complement the outer element in providing the desired shape for the finished opening, said wall terminating in an outwardly extending flange; the adjacent sur-faces of the flanges of the said inner and outer elements providing, between said opposing surfaces, a peripheral recess which configured to receive and support a portion of the gasket strip first mentioned; said shaping elements being provided with releasable clamping means simultane-ously to site the shaping elements at a predetermined location within the manhole wall thereby to site said opening, and to hold them together in use and impose a limited pressure on said gasket.

11. In a method of installing a sealing element for use be-tween the outer surfaces of a pipe and an opening in a masonry wall through which the said pipe passes, which method comprising the steps of:
casting a wall of settable material about a sectional shaping member sited at a predetermined movable location with respect to said masonry wall configured to produce an opening at the desired location and of the de-sired dimensions to pass the said pipe in slightly spaced relation there-to; said shaping member being provided with means defining a peripheral channel configured to engage a peripheral gasket ring of resilient ma-terial and to house a substantial portion only of the said ring, leaving a remaining portion extending into the settable material as it is being emplaced; permitting said material to set, and thereafter removing the shaping member.

12. The method of installing a sealing element in the peripher-al surface of an opening through the body of a manhole wall, which method comprises the steps of installing at a predetermined movable location, between the inner and outer shells of a form for casting the concrete wall of a manhole, a two-part mold, comprising:
(a) an inner mold member of dished shaped having radially outwardly extending flanges thereon of greater diame-ter than said opening;
(b) an outer mold member of complementary dished shaped having side flanges thereon of the same diameter as said opening;
said mold being configured to hold a portion only of an elastomeric gasket strip, leaving other structure of the gasket strip projecting outwardly from said mold; positioning said mold between said shells by means of a depending bar held to said outer shell and temporarily but firmly secured to said and pouring settable material into the space be-tween the inner and outer shells so as to surround and enclose said mold, and so as to surround and enclose those portions of the gasket strip which are not received within the mold; permitting the settable material to set, and then removing the inner and outer forms and separating and removing the two parts of the mold, thus leaving that portion of the gasket strip which had been embedded in the mold projecting into the opening in the body of the manhole wall.

13. A method of manufacture of a pre-cast portion of an access pit for underground piping systems comprising the steps of:
assembling an annular elastomeric seal body on a mandrel, two part mandrel comprising:
(a) an inner mold member of dished shaped having radially outwardly extending flanges thereon of greater dia-meter than said opening;
(b) an outer mold member of complementary dished shaped having side flanges thereon of the same diameter as said opening;
(c) means between the outer periphery of a flange on said outer mold member and a flange on the inner mold mem-ber adapted to receive the pipe-engaging portion of said gasket and to allow the anchoring portion of said gasket to project radially outwardly;
fixing said assembly to one of a pair of form members and positioned between said members by means of a depending bar held to said outer shell and temporarily but firmly secured to said;
pouring concrete between said form members and around said assembly; and removing said form members and said mandrers after said concrete has set.