US3265782A - Process for sealing mains - Google Patents

Description

w. E. ROSENGARTEN, JR, ET AL 3,265,782

Aug. 9, 1966 PROCESS FOR SEALING MAINS Original Filed May '7, 1962 4 Sheets-Sheet 1 w m 9% r W p 1 2 y L f Z w M m g- 1966 I w. E. ROSENGARTEN, JR, ETAL 3,265,782

, PROCESS FOR SEALING MAINS 4 Sheets-Sheet z 1 9, 1966 w. E. ROSENGARTEN, JR, ETAL 3,265,782

PROCESS FOR SEALING MAINS Original Filed May 7, 1962 4 Sheets-Sheet 4.

w V Z a m e/ a a i K M W ATTORNEYS United States Patent 3,265,782 PROCESS FOR SEALING MAINS Walter E. Rosengarten, Jr., 2895 Gradyville Road, Broomall, Pa., and Archibald T. Flower, Gleuside, and David L. Buchanan, Flourtown, Pa.; said Flower and gait! Buchanan assignors to said Rosengarten, Broomall,

a. i D al application May 7, 1962, Ser. No. 192,817, now Patent No. 3,178,793, dated Apr. 20, 1965. Divided and this application Jan. 25, 1965, Ser. No. 427,638 Claims. (Cl. 264-32) The present invention is a division of our co-pending application Serial No. 192,817, filed on May 7, 1962, for Process and Apparatus for Sealing Mains.

The present invention relates to a process for sealing mains and particularly to a process for sealing bell and spigot joints in existing mains carrying fluids such as fuel gas, water and other liquids.

An object of this invention is to provide a method for sealing gas mains atthe joints by applying a mold there to from a position remote to the main.

It is a further purpose to provide a method for sealing gas mains which permits a substantial reduction in the size of the excavation required and in the area of the pavement which must be destroyed in order to gain access to the main.

A further object of this invention is to provide a method for sealing gas mains which keeps the main in service while it is being sealed.

Additionally it is an object of this invention to seal gas mains by surrounding the main with a flexible mold on an articulated frame tightening the mold against the joint and subsequently introducing sealing material into the mold.

A still further object of the invention is to provide a method for sealing joints which permits the restoration of trafiic conditions during non-working hours by keeping the mold mechanism below the surface level during setting or curing and by applying a cover over the top of the hole.

A further object of this invention is to seal a pipe joint in a main by applying a reusable mold to the joint, introducing sealing material into the mold to seal the joint and subsequently removing the mold and applying it to another jointto be sealed.

A further purpose is to provide a method for cleaning the joint prior to attaching the mold.

The drawings illustrate by way of example one embodiment of a sealing device and one embodiment of a cleaning device which may be used in the sealing of gas main joints according to theobjects of this invention.

FIGURE 1 is an axial elevation of the cleaning device of the invention about to be inserted on a main.

FIGURE 2 is a section taken on the line 2-2 of FIG- URE l. 1

FIGURE 3 is an enlarged sectional view taken on the line 3-3 of FIGURE 1.

FIGURE 4 is an enlarged partial sectional elevation of the frame and nozzle of the cleaning device of the invention.

FIGURE 5 is an axial elevation of the cleaning deviceof the invention applied to the top side of a main.

FIGURE 6 is an axial elevation of the cleaning device of the invention showing the nozzle at the underside of the pipe.

FIGURE 7 is a section taken on the line 77 of FIG- URE 5.

FIGURE 8 is a transverse section through the pipe,

- showing the mold of the invention being applied to a main at a bell and spigot joint.

FIGURE 9 is a partial axial elevation of the mold de- 3,265,782 Patented August 9, 1966 vice of the invention in place on a main for molding.

FIGURE 10 is an enlarged section taken on the line 10-10 of FIGURE 9.

FIGURE 11 is a fragmentary plan view of the mold of the invention.

FIGURE 12 is a section taken on the line 1212 of FIGURE 11.-

FIGURE 13 is a section taken on the line 1313 of FIGURE 8. Y

FIGURES 14 to 17 show the various steps in sealing a bell and spigot joint using the present invention.

FIGURE 14 is a fragmentary longitudinal elevation showing the cleaning device of the invention being applied to the joint.

FIGURE 15 shows a vacuum cleaner to suck sand and loose earth out of the hole being applied to clean the joint.

FIGURE 16 shows the mold of the invention applied to the joint. I

FIGURE 17 shows the manner in which the mold may be left in the hole while the sealing material is setting.

FIGURE 18 is an enlarged exploded sectional perspective of a mold and articulated frame.

FIGURE 19 is enlarged fragmentary side elevation showing the clamp and the related handle.

FIGURE 20 is a top view of the clamp and related handle shown in FIGURE 19, with the handle in section.

Describing in illustration but not in limitation and referring to the drawings:

In the distribution of gas for domestic, commercial, and industrial use, a network of mains is employed to carry the gas from central points to points of usage. These mains in many instances have bell and spigot joints which are typically packed by jute and then usually leaded or cemented at the outside. When these joints were originally installed, many of the mains were distributing carbureted water gas or coke oven gas which contained a substantial content of moisture, tars and oils. These liquids had over a period of time, saturated the packing materials to provide relatively leak-free joints.

' In recent years, there has been a shift over to natural gas which is of a comparatively d-ry nature. The natural gas has reduced by absorption the content of tars and oils which has been built up in the joints, and thus drying out the joints. Furthermore, many of the textile packing materials tend to shrink when they dry. The result encountered in a widespread way has been a tendency of the packing to shrink, causing openings through the dried-out packing which permit leakage of gas.

In other instances, leaks have. been caused in many areas of the country by active earth conditions which in certain localized areas has involved settling ormovement of the earth in the order of half inch or even one inch a year. This settling has caused a certain tendency for misalignment of the various pipe section-s, both vertically and also horizontally, and this has further increased the.

' tendency toward leakage. This misalignment in some instances has caused a withdrawal to some extent of the pipe from the spigot causing additional leakage.

All of these factors have made it quite important to develop some technique for sealing the joints. One approach to the problem has been to cut out the line, and actually introduce a self-propelled crawler which both cleans the line and locates the joint, sometimes electronically, and then to coat the inside with a suitable sealing which may be used without taking the line out of service.

These usually involved digging an excavation at each joint large enough for a man to descend to the area around the hell or pipe and to fix a bolted clamp fitting around the joint. The fitting compresses a rubber gasket which seals against the outside of the bell and also against the adjoining straight pipe section of the spigot.

There is also another technique which in effect butters epoxy resin around the face of the bell in order to accomplish sealing. This method also requires extensive excavation.

The present invention permits the line to remain in service at normal (superatmospheric) pressure without any interruption of gas flow and can be carried on with a minimum of excavation. The process and equipment can function using a slit about 18 inches in length and about 4 inches in width where it penetrates the sidewalk or other paving, and slightly wider in the earth at the bottom where the pipe joint is located.

The present invention as compared to any preformed gasket technique gives greatly improved seal by providing a bond to the metal surface.

Principally due to the reduced amount of excavation, the speed of the operation is considerably increased compared 'to the other techniques. It is believed that the time is not more than one-half that of the best prior technique.

By virtue of the relatively very small size of the opening in the paving it is much less costly to rcpave after sealing the leak than it was in prior art methods. In addition high-way authorities have permitted openings of this size in paving to be repaired with a mere block of concrete, rather than expensive cutback and repaving according to specifications. This provides quite substantial savings. Also, it is usually possible to work around reenforcing rods in concrete paving, thus eliminating the necessity for replacing and/or tie welding new rods when repaving.

In accordance wtih the present invention, a suitable cleaning technique is employed which may conveniently be sand-blasting but could be grit-blasting, wheat blasting or refractory blasting. Alternatively, the joint could be cleaned by wire brushing, scraping or by solvent. After the cleaning has been completed a mold is introduced about the joint more or less by remote control since the operator is at ground level. A suitable sealing material is introduced under pressure into the mold space.

Considering now the invention in detail, the preferred sand-blasting device is shown in FIGURES 1 to 7, inclusive. A handle 20 is pivotally connected at 21 to frame 22 having arcuate elements 23 and 24 suitably pivoted at 25. A connector element 26 supports elements 23 and 24 to pivot and also supports pivot 27 to which handle 20 is attached at 21. Handle 20 has a suitable U-shaped bend 28 at the end adjacent frame 22. Rollers '30 are pivotally mounted on arcuate elements 23 and 24 which engage circumferentially on the pipe 116. As best seen in FIGURE 7, there are two rollers 30 on the outer end of element 23 and one roller near the pivot and one roller on the outer end of element 24, the rollers being disposed at approximately 120 intervals around the circumferonce. A nut and bolt 31 retains helical compression spring 32 which biases the segments 23 and 24 together as best seen in FIGURE 4.

A nozzle 33 having orifice opening 34 is held to arcuate element 24 by extension 35 and retainer 36. Retainer 36 is held against extension 35 by nuts and bolts 37 which are spring loaded by helical compression springs 38 to secure the nozzle 33 by engaging surface 40 of the nozzle. A shoulder 41 and nut 42 threaded on nozzle 33 prevent longitudinal movement of the nozzle with respect to the arcuate element 24. The spring loaded yieldable retainer 36 allows the nozzle 33 to be rotated selectively.

A hose 43 is connected to the nozzle at 44 whereby sand or other abrasive can be brought to the nozzle and into contact with the pipe, the hose being connected at the outer end to any suitable air compressor and abrasive pickup mechanism as well known.

Considering now the mold, frame, and handle of the invention as best seen in FIGURE 8, a mold suitably of any flexible resilient material such as rubber or the like, has a radial separation 51. The mold shape conforms circumferentially to a pipe circumference for covering a bell and spigot joint and leaves suitable interior space for sealing material to be introduced. The mold in longitudinal section, as best seen in FIGURES l0 and 18, comprises a flange section 52 of an inner circumference conforming in a closed position to the circumference of the spigot 53. A radially extending web 54 extends for a suitable distance, and has at its radially outward extremity a longitudinally extending flange 55 whose inner face 56 conforms circumferentially to the outer face of the bell 57. An integral circumferential extension 58 extends circumferentially around flange portion 55.

Two circumferentially spaced radially extending openings 61 and 62 extend through the mold. At the inner face of the mold 50 a bevel face 64 extends from the spigot to the bell when the mold is in closed position during the scaling of a joint. Thus, there is created a circumferentially extending mold cavity 65 about the bell and spigot joint. This mold cavity 65 extends longitudinally adjacent existing lead packing 66 and jute packing 67. In some cases cement has been used instead of lead.

Extending circumferentially around and radially outward from flexible mold 50 is an articulated circumferentially segmented frame 68. Frame 68 is composed of a plurality of longitudinally segmented segments 70 and 71 which are held in radial relation to one another in a circle and in abutting relationship to mold 50 by a leaf spring 70' which passes circumferentially around the outside of the mold 50 and passes over a series of bolts 71 which longitudinally loosely join segments 70 and 71.

It should be understood that while the action of one pair of segments is described, these segments extend around the complete circumference of the mold as at 72.

As shown in FIGURE 18, segment 70 has a portion 74 which rests against the flange 52 of mold 50, a web 75 which extends radially outward and has extending at right angles a portion 76 with a bearing surface which circumferentially rests against mold 50. A radially outwardly extending portion 77 has at its radially outer end lateral extensions 78 adjacent its circumferential ends which engage with notched portions on mating longitudinal segment 71.

Mating longitudinal segment 71 has a radially extending flange 80 which conforms to the longitudinal extension 55 of mold 50. A circumferential portion 81 fits against the mold at its outer circumference and has a radially extended portion 82 whose inward surface has circumferential notches 83 at its radially outer end for engagement with the extensions 78. It should be noted that the notches form fulcrums for the pointed extensions 78 on the mating longitudinal segment 70 which act to form pivots for the longitudinal segments. This serves to articulate the mold frame both radially and longitudinally, so that the mold will always close against the outside of the spigot and against the outside of the hell even though one or the other may lack perfect concentricity or may vary somewhat in diameter.

The portions 77 and 82 of the respective segments 70 and 71 carry longitudinally inward circumferential extensions 84 disposed adjacent their radial inner ends. The longitudinal sections of the frame 70 and 71 are held together in position by the bolt 71' which passes through a longitudinal opening 79 centrally in the portion 77 of the segment 70 and engages a threaded corresponding opening 79' in the portion 82 of the segment 71. The extension 58 of the mold 50 is engaged between the portions 77 and 82 in such manner that the extensions 84 engage the indent at 60 the radial inward portions of the lateral sides of the extension 58 and hold the mold 50 securely in the position as shown in FIGURE 10. The radial outward edge of the extension 58 has notches 59 which engage the respective bolts 71 and properly position the several segments of frame 68 with respect to the mold 50.

Radially outward extensions 85 of the portions 76 and 81 having circumferential openings 86 receive flexible cables 87 which extend circumferentially around the mold frame radially in'ward of the bolt 71 and force the frame segments radially inward upon the application of tension to the cables. When the elements shown in FIGURE 18 are assembled as in FIGURES 8 to '12 inclusive, the spring 70' is disposed radially outward of the bolts 71' and radially inward of the extensions 78.

A terminal segment 88 has attached thereto an arcuate guide 90 by bolting or other means. The guide 90 has a bevelled end portion 91 at one end and a handle 92 of suitable length and desirably of tubular construction which extends tangentially from the mold frame. This handle can be suitably for instance of a length of seven feet so that it can conveniently be manipulated from above the ground. The handle is desirably subdivided at 93 by telescoping or by any other suitable means. The handle has at its end away from the mold a tension mechanism which can suitably be of the conventional jack type as shown at 94. This jack mechanism 94 has a portion 95 extending longitudinally of handle 92 and is, for instance, of rectangular cross section having spaced notches 96.

A lever 97 has suitable fulcrum and engaging means not shown for engaging notches 96 whereby a mechanical advantage is secured so that a tangential force applied in a direction away from the mold can be secured on a curved saddle 98 by the application of force on lever 97. The curved saddle 98 receives a loop integral with and formed from cables 87.

Guides 100 lying in parallel planes transverse to the pipe axis extend circumferentially from the side faces of the terminal segment 88. The guides 100 act to guide terminal segment 101 into position longitudinally and the guide 91 acts to align segment 101 with segment 88 circumferentially when force is applied to cable 87. When the mold 50 is in closed position, as best seen in FIGURE 12, the mold 50 has terminal faces 102 and 103 which come into abutting relationship and serve to form a closed mold which extends circumferentially continuously about the bell and spigot joint.

A clamp 104 is fixed to theportion of the handle closest to the frame in such manner that the cable 87 can be clamped by tightening bolt 105 so that the force at the jack mechanism 94 may be released without releasing the force exerted by the cable at the mold frame.

Clamp 104 is comprised of a channel element 121 bent into a right angle with outwardly protruding flanges, having a longitudinal extension 122 of a substantial part of the web of one leg 12-3' of the angle and an opening 124 in the web of the other leg 123. The wheel-handled bolt 105 passes through the opening 124 and engages a threaded opening 125 in a keeper element 126, conveniently of a channel similar to element 121, which is provided with a slot 127 to receive and anchor the enlarged end of the extension 122, the latter beingspread at the end to prevent separation of the elements 121 and 126.

The handle 92 is provided with a transverse opening 128 offset from the diameter, to receive the bolt 105. The clamp 104 is applied to the handle 92 so that the leg 123 is adjacent the side nearest the opening 128. The clamp in the open position receives cables 87 in such manner that they are engaged between the jaws 123 and 126 of the clamp beyond dead center or inward of a diameter of the handle 92. When the clamp is tightened, the cables are thus firmly grasped and tend to be forced inwardly of the jaws toward the leg 123 rather than to be squeezed out therefrom. I

Extending through the radially extending openings 61 and 62 is an inlet orifice 107 and an outlet orifice 106 which can suitably be short lengths of small diameter rigid tubing. Connected to the inlet orifice 107 is flexible tubing 110 and connected to the outlet orifice 106 is flexible tubing 108. Fluid plastic is supplied through opening 111 of tube 110 and controlled by valve 114. Outlet tube 106 connects through tube 108, through pressure indicating gauge 113 and through valve 112 to the atmosphere.

The process of the invention can use any suitable curable sealing material, although we have preferably used an epoxy resin of the character described in the text, Epoxy Resins: Their Application and Technology," published in 1957, by H. Lee and K. Neville.

It will be evident that in the preferred embodiment the sealing material should have several different properties which will cooperate to render it most suitable for use in the present invention. The sealant should initially be a liquid which can be injected into the mold under a moderate pressure. After the sealant has been injected and has filled the mold, it should undergo a change of state within a reasonable time and not excessive time. For good results the change should not take place until about fifteen minutes have elapsed so as to allow adequate time for injection, and the change should take place within six-teen hours so that it will not be necessary to leave the mold in place indefinitely. The material may cure or set either chemically, as by polymerizing or cross linking, or other plastic curing mechanism, or it may simply cool and solidify. The sealant should form a bond of adequate strength to the suitably clean surface of the main. Thus, where the main is of cast iron cleaned by sand-blasting, we have found that bonds having an adhesive tensile strength of the order of 500 psi. can readily be obtained by using the epoxy resins above referred to. The sealant should of course be capable of releasing from the mold by a suitable mold release agent as well known.

The sealant in its final form should preferably remain flexible to a sufiicient extent to absorb energy due to traflic passing overhead without failure. The sealant should also be resistant to chemical deterioration by contact-with the earth and the medium within the main, and therefore should not undergo softening, cracking, dissolving or disintregation within its normal service life.

The sealant in its final form should have negligible cold flow at normal temperatures and under the pressure to which it is normally subjected.

In operation, a 'hole 115 is dug from the street or pavement surface to the level of the main 116. This hole can be suitably of a cross section of 4" x 18" at the surface and is then extended to any necessary dimension surrounding the pipe to introduce the mechanism for cleaning and sealing. After digging and cleaning the hole the cleaning device 20 is lowered into the hole with the arcuate sections 23 and 24 disposed on either side of the top portion of the pipe 116. The arcuate sections 23 and 24 are normally biased toward a closed or radially inward position by helical spring 32 acting against nut and bolt 31. The arcuate sections 23 and 24 are extended by forcing the rollers 30 against the pipe section in a downward direction so the sections expand and then contract and snap into place about the pipe.

The operator uses the handle 20 to maneuver the sections 23 and 24 carrying noule33 with its opening 34. The arcuate sections 23 and 24 are rotated around the pipe into positions shown in FIGURE 5 and FIGURE 6 as the blast is applied to the face of the bell as shown in FIGURE 2, or to the spigot as shown in FIGURE 5. The shoulder 41 is provided with radial studs 49 so that the nozzle may be rotated with a suitable forked rod applied from above ground for adjustment of the direction of the blast. .It is also relatively easyfto remove the cleaning device from the hole to rotate the nozzle 33 to get a selected-direction for the blast. The cleaning device is rotated through the entire 360 circumference of the pipe by alternatively flopping the handle so that the U bend 28 is on the one side of the pipe during the 180 of rotation as shown in FIGURE 5, and then on the other side of the pipe through the remaining 180 of rotation as shown in FIGURE 6. The handle rotates about the pivot 27 during this flopping from one side to the other.

After the bell and spigot have been sand-blasted, the cleaning'meohanism is removed by pulling upwardly on the handle. A suction cleaner 119 is then introduced into hole 115, as shown in FIGURE 15, and the grit or blast material is removed from the hole and from the vicinity of the joint.

The mold device of. the invention is then introduced into the hole by the following method. The cable 87 which forms the loop around saddle 98 is removed and dropped into the hole on one side of the pipe while the rest of the device is above the hole. mechanism, such as a pole with a hook on the end, is introduced on the opposite side of the pipe and the loop of cable 87 in the hole is fished under the main. Also, a block of magnetic material may be attached to the bight of the cable and a suitable fishing magnet can then be used to pull the cable through under the main. T-he mold and frame are then lowered by means of handle 92. The mold and frame are in an open position, as shown in FIGURE 8, by virtue of the resilience of the flexible mold which has a tendency to circumferentially separate at faces 102 and 103 so that a gap exists between these faces as shown in FIGURE 8.

The mold and frame are lowered completely over the main as shown in FIGURE 9. This is conveniently accomplished by alternatively pushing down on the handle 92 and pulling up on the cable which has been passed under the pipe. The bight of the cable 87 is then looped over the saddle 98. The guides 90 and on the terminal segment 88 guide the terminal segment 101 of the frame into position as tension is applied to cable 87 by saddle 98 so that the cable is drawn upwardly along the handle by operation of the jack mechanism.

A linear force on cable 87 along handle 92 is converted to a tangential force at 117 (FIGURE 9) so that a radially inward force is created by the cable at each segment of the mold frame. Since separate cable portions extend circumferentially along longitudinal segments 70 and 71, separate radial forces are exerted upon these segments, Each segment 71 acts independently against mold section 55 to contract and retain the mold against the outer circumferential face of the bell end. Each segment 70 also acts independently against mold section 52 to contract and retain the mold against the spigot.

By virtue of these articulated segments compensation is automatically made for any variance of the bell or spigot from true roundness and for any'variance of any fixed relationship between the bell and the spigot longitudinally, axially or otherwise. i

A suitable sealing compound is introduced through open valve 114 and tube under pressure and through inlet opening 107 into mold cavity 65. Gases from the cavity escape through outlet opening 106 and outlet tube 108 through open valve 112 to atmosphere. As soon as the sealing fluid emerges through outlet open- 106 and is seen in transparent outlet tube 108, valve 112 is closed and the pressure is increased until it is slightly in excess of the pressure of the gas in the main, so that the sealant is forced into leak-passages and escape of gas is prevented and thus a tendency to form gas bubbles in the plastic sealing compound will not exist. The pressure of the air above the sealant in outlet tube 108 is read on gage 113. .The pressure on said material is maintained until it has hardened. As the sealant cures it may have a tendency to shrink which together with the expansion of the plastic tubes 108 and 110 would cause a drop in pressure as registered on gage 113. Fitting A suitable fishing -104 which secures the cable under tension to the handle by tightening bolt 105. This allows force to be released on the cable at saddle 98 without releasing the tangential force being applied to the mold frame. The jack mechanism and the outmost sections of the handle are removed and the cable loop is permitted to drop into the hole as best seen in FIGURE 17. In this position, the entire mold mechanism and the lower portion of the handle is below the surface of the pavement and a hole cover 118 is placed over the hole,'secured in place if desired. In this condition trafiic, both vehicular and pedestrain, can move over the covered hole in safety.

After the sealing material sets in the cavity 64, for example, from less than one hour to about twelve hours, depending upon the sealant used, tension on cable 87 is released and the cable loop is allowed to drop into the hole. The resilience of the mold causes the mold and frame to open as shown in FIGURE 8, especially if a suitable parting compound has been employed to permit separation from the sealing material, and the mold and frame are removed from the hole by use of the handle 92. The fill and vent tubes 107 and 106 and the associated plastic tubing are replaced with new tubes and the mold recoated with the release agent and the apparatus is then ready to reuse. The advantage of using sealants with shorter curing time is that more joints can be rescaled per day with a single sealing apparatus.

In view of our invention and disclosure, variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of our invention without copying the method and structure shown, and we, therefore, claim all such insofar as they fall within the reasonable spirit and scope of our claims.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

l. A method of sealing an area of an underground conduit containing fluid under superatmospheric pressure, which comprises the steps of excavating a narrow shaft above an area of the conduit to be sealed, lowering into the excavation and disposing in open position partially surrounding the conduit a split elastomeric mold, closing said mold about the area of the conduit to be sealed, applying radially inward force to the outside of the mold to press said mold into tight radial engagement with the conduit leaving a completely annular space between said mold and the area of the conduit to be sealed, introducing a hardenable sealing material into the space between the mold and the area of the conduit to be sealed under external pressure in excess of the pressure in the conduit and at the same time pushing out the gases in said space to the atmosphere ahead of the sealing material, and when the sealant fills the mold maintaining the tight engagement of said mold with said conduit and the pressure on said material in excess of the pressure in the conduit until the material has hardened.

-2. A method of claim 1, in which said radially inward force is produced by applying tension on flexible circumferential elements surrounding said mold from above the surface of the excavation.

3. A method of claim 1, in which said conduit is a gas main, and in which leakage occurs from the gas main at said area, through an aperture in the conduit wall in the area, which further comprises introducing said hardenable sealing material from said space into said aperture, notwithstanding the pressure in the main, thereby sealing said leakage.

hardenable sealing material into the space between the 4. A method of sealing an area of an underground gagement of said mold with said conduit and the pres conduit containing fluid under 'superatmospheric pressure on said material in excess of the pressure in the sure, which comprises the steps of excavating a narrow conduit until the material has hardened. shaft above an area of the conduit to be sealed, lowering 5. A mcthcd of claim 4, wherein after said material into the excavation and disposing in open position par- 5 has hardened, the external pressure on the material is tially surrounding the conduit a split'elastomeric mold relieved, the circumferential force is removed from the within a coextensive longitudinally and transversely fr me, th mold is r leased from engagement with the articulated segmented reinforcing frame having longi conduit, and the mold and frame are opened and removed tudinally separate groups of segments, closing said mold from the excavation. and said frame about the area of the conduit to be sealed, 10

applying circumferentail tensile forces on the respective References Cited by the Examm" longitudinal groups of segments of said frame to press UNITED STATES PATENTS said mold into tight radial engagement with the conduit 2 055 885 9/1936 Weston 25 127 XR leaving a, completely annular space between said mold 2163261 6/1939 Norton a n and the area of the conduit to be sealed, introducing a 15 2:2 g:0 9 7 941 Evans 5 127 mold and the area of the conduit to be sealed under ex- FOREIGN PArlrENTs ternal pressure in excess of the pressure in the conduit 721,664 1/1955 Great Britain.

and at the same time pushing out the gases in -said space; to the atmosphere ahead ofthe sealing material, and 20 ROBERT WHTTE, when the sealant fills the mold maintaining the tight en- J. A. FINLAYSON, Assistant Examiner.

Claims (1)

1. A METHOD OF SEALING AN AREA OF AN UNDERGROUND CONDUIT CONTAINING FLUID UNDER SUPERATMOSPHERIC PRESSURE WHICH COMPRISES THE STEPS OF EXCAVATING A NARROW SHAFT ABOVE AN AREA OF THE CONDUIT TO BE SEALED, LOWERING INTO THE EXCAVATION AND DISPOSING IN OPEN POSITION PARTIALLY SURROUNDING THE CONDUIT A SPLIT ELASTOMERIC MOLD, CLOSING SAID MOLD ABOUT THE AREA OF THE CONDUIT TO BE SEALED, APPLYING RADIALLY INWARD FORCE TO THE OUTSIDE OF THE MOLD TO PRESS SAID MOLD INTO TIGHT RADIAL ENGAGEMENT WITH THE CONDUIT LEAVING A COMPLETELY ANNULAR SPACE BETWEEN SAID MOLD AND THE AREA OF THE CONDUIT TO BE

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