IE891375L

IE891375L - Pipe connection

Info

Publication number: IE891375L
Application number: IE891375A
Authority: IE
Inventors: Siegfried Hopperdietzel
Original assignee: Himont Inc
Priority date: 1988-05-03
Filing date: 1989-04-26
Publication date: 1989-11-03
Also published as: NO891672D0; DK171812B1; ATE91768T1; IE63101B1; FI892046A; DK206589D0; PT90445B; FI892046A0; DE3814913A1; NO891672L; PT90445A; FI90794B; EP0340499A1; EP0340499B1; DK206589A; ES2042852T3; FI90794C; DE3814913C2

Abstract

The invention relates to a pipe joint for propulsion pipes or the like, having joining elements in each case on the free ends of the individual pipes. In the joining region there is a flexible sealing element (3) for sealing the connected pipes (1). The pipe wall (13) in this region is displaced backwards on at least one free end (11, 12) as a mirror image of the surrounding sleeve end, in stepped segments (121, 122, 131, 132) of corresponding length and depth. An additional retaining slot (123, 133), for forming a retaining chamber (15), is incorporated in each case on the inner circumference at a defined distance from the free end (111) of the sleeve end (11) and from the free end (124) of the plug end (12). A locking element (2) is inserted into this retaining chamber (15) from the outside, via an opening (14) in the pipe wall. The sealing element (3) is located between the free end (124) of the plug end (12) and the supporting shoulder (112) of the sleeve end (11). In this way, a pipe joint is produced which is resistant to tension and compression forces in equal measure and which is still designed to be fluid-proof by means of the partially- compressed sealing element (3). <IMAGE>

Description

6 3101 The invention relates to a pipe joint for two pipe-jacking pipes or the like, wherein on placing together of the pipes a plug end formed at one end of one of the pipes engages into a socket end formed at one end of the second pipe, the wall 5 thickness of the pipes at the plug end and the socket end being reduced by a radially inward and a radially outward turned step respectively and the height of the step at the ' plug end matching the height of the step at the socket end, wherein on placing together of the pipes a flexible sealing 10 element is inserted between the free end of the plug end and the adjacent region of the socket end, and wherein at a distance from the free end of the plug end and at a distance from the free end of the socket end location grooves are disposed on the outer periphery of the plug end and on the 15 inner periphery of the socket end respectively, said location grooves upon striking of the free end of the socket end against the locating shoulder formed by the step on the plug end forming a receiving chamber into which, once the pipes have been placed together, is let a locking element which is 20 inserted from outside through an opening in the pipe wall.

A field which in recent times has grown in importance is renovation of leaking liquid-carrying conduits such as sewers etc. This has led to the development of various renovation processes, with a process whereby existing conduits are 25 repaired using short pipe portions - known in the trade as short-pipe relining - having become predominant.

In said process, short pipe portions are pushed into the defective pipeline conduits via the inspection chambers of the existing pipe system, without excavation. However, since the 3 0 inside dimensions of said inspection chambers are limited, the possible installation length of the individual pipe portions is also limited. Relatively short pipe pieces of around 1 ns ' in length are used in said process. » 1 Said locking elements are locking bar bodies with sharpened ends, which are driven into the receiving chamber formed by the location grooves.

From DE-B 1 525 525 a pipe joint is known, which has connecting elements at the free ends of the individual pipes as well as a flexible sealing element for sealing off assembled pipes in the joint region. At at least one free end, the pipe wall of the individual pipes is set back, in a mirror-image manner relative to the socket end engaging over it, in graduated steps of matching length and depth. At a defined distance from the free end of the socket end and from the free end of the plug end, at the inner periphery a respective additional location groove is let into the remaining pipe wall to form a receiving chamber for a locking element which is insertable from outside through an opening in the pipe wall, and the sealing element is inserted between the free end of the plug end and the locating shoulder of the socket end.

With said type of plug-and-socket joint, once the mirror-image-shaped pipe ends have been inserted one into the other, no pressing power is exerted in an axial direction upon the sealing element, so that there is no guarantee that the pipe joint created is absolutely tight.

The object of the invention is to provide a pipe joint of the type described initially, whereby the two pipes may easily be joined to one another in a compression- and tension-resistant manner, while simultaneously generating an axial pressure on the sealing ring.

Said object is achieved according to the invention in that the axial length of the stepped region of the plug end is shorter than the axial length of the stepped region of the socket end, and that once the pipes have been placed together the sealing element is held in a press fit on the one hand by the free end of the plug end and on the other hand by the locating shoulder of the socket end.

The pipe joint according to the invention is used in pipes having a plug end at one end and a socket end at the other. The wall thickness is reduced at the socket end by a radially outward turned step and at the plug end by a radially inward turned step. The plug end may be pushed into the socket end, with the open surfaces sliding along one another and the location grooves forming the receiving chamber for the locking element which is insertable from outside through the pipe wall opening. Said locking element may - since the two location grooves lie precisely one above the other when the free end of the socket end strikes against the locating shoulder of the plug end - easily be inserted from outside through the tangential pipe wall opening into the receiving chamber.

It has proved advantageous if the sealing element, once the pipes have been placed together, is laterally delimited by the free end of the plug end and by the locating shoulder of the socket end. In order for the pipe joint to be able to take up manufacturing tolerances and deformation resulting from thrust load or bending stress without starting to leak, a seal of the greatest possible volume is required. In said respect, it may be assumed that a compression seal designed for sustained tightness is capable of taking up a maximum compression of 30% of the original cross section without, in the long term, failing as a result of permanent deformation. To achieve absolute tightness, a minimum compression of a compression seal of about 10% is necessary, i.e. for taking up the above-mentioned manufacturing tolerances and deformation, roughly 20% of the sealing ring height remains available for compression.

When the free end of the socket end strikes against the locating shoulder of the plug end, compression of the sealing ring inserted between the free end of the plug end and the locating shoulder of the socket end is effected.

Since under said compression the sealing ring yields into the clear interior of the pipeline, it further appears advantageous not to place the seal into the parting line 5 between the locating shoulder of the socket end and the free end of the plug end, but to let an insert groove for the sealing element into the locating shoulder of the socket end in a direction along the pipe axis. Said groove is so deep that part-regions of the sealing element project outwards 10 towards the free end of the plug end. The projecting length should be great enough to allow the maximum sealing ring compression of 30%.

A further possible way of inserting the sealing element is provided in that, in the region of the locating shoulder of 15 the socket end, an insert groove for the sealing element is let in a radial direction into the pipe wall. Here too, it is necessary to take into account the maximum compressibility of 30%. In said form of construction, the free end of the plug end is advantageously bevelled towards the seal, thereby 20 allowing improved compression of the seal.

The last two sealing options described involve a locking in position of the sealing ring, so that it is prevented from being pushed or pulled out by specific operating conditions. Furthermore, as a result of said type of seal, it is possible 25 to keep small the gap arising after assembly between the plug end and the socket end in accordance with the maximum sealing ring compression of 30% which has to be taken into consideration.

The pipe joint according to the invention provides a means of 30 joining whereby no step arises either at the pipe exterior or the internal diameter. Said advantage may be achieved when one end of the pipe takes the form of a plug end and the other end takes the form of a socket end. Alternatively, however, 4 both ends of the pipe may take the form of plug ends if, for example, a double-ended socket is used to join two such pipes. The joint itself and its properties remain the same.

Because of the smooth, continuous transition at the exterior 5 of the pipe from one pipe to the next, pushing or drawing of the pipes into the pipe to be renovated is made much easier. The same advantages arise in the case of direct laying of pipelines without digging trenches, e.g. thrust-boring pipes through a channel of earth which may be produced using various 10 methods.

If the pipe cross-section is narrowed on the inside in the region of the socket joint, this leads not only to cross-sectional losses and hence to increased pressure losses in the case of nonpressure conduits but also to regions in each 15 individual pipe portion where water cannot flow away, i.e. water remains stagnant in the pipe system. Since such "water pockets" are to be avoided at all cost in wastewater systems, in this respect too the pipe joint according to the invention offers a considerable advantage because on the inside also 20 there is a continuous transition from pipe to pipe.

Finally, it is an advantage that the pipe joint according to the invention is equally suitable for pushing through and for drawing through. The joint is capable of taking up the high tensile or compressive loads arising during pushing or drawing 25 through at the socket joints because, at said points, the locking element immovably fixed in the receiving chamber effects non-positive interlocking of the joined pipe portions.

The pipe joint according to the invention may in principle be used for pipes made of different materials such as 30 thermoplastics or thermosetting plastics, fibre cement, steel, concrete. The dimensions of the socket system should then be adapted to the strength characteristics of the relevant material.

Embodiments of the pipe joint according to the invention are illustrated diagrammatically in the drawings; the drawings show: » Fig.l a pipe with part-sectioned regions of the socket end and the plug end; Fig.2 a partial cross-section of the pipe joint, with a locking element inserted into the receiving chamber; Fig.3 a partial longitudinal section through a pipe joint with a locking element and sealing ring; Fig.4 a partial longitudinal section according to Fig. 3 with a special sealing ring seat; Fig.5 a partial longitudinal section according to Fig.3 with a further special sealing ring seat.

Fig.l shows the pipe 1 with its socket end 11 and the plug end 12. The pipe 1 has a wall thickness 13. At the socket end 11 and at the plug end 12 there are regions 131, 132, 121, 122 of reduced wall thickness. In the socket end 11, a pipe wall opening 14 is let tangentially from the outside into the pipe 20 wall directly above and aligned with the location groove 133. The pipe wall opening 14 has a predetermined longitudinal expansion range and extends through the pipe wall as far as into the location groove 133.

Fig.2 is a partial cross-sectional view of the joint of two 25 pipes 1 according to Fig.l. The partial cross-sectional view illustrates the situation in which the plug end 12 of one pipe 1 is inserted into the socket end 11 of a following pipe 1. Said insertion process is complete when the groove 133 of the socket end 11 lies precisely above the groove 123 of the plug 3 0 end 12. The two location grooves 123, 133 form the receiving 6 chamber 15 for the locking element 2. From the point of view of its dimensions, the locking element 2 is so fashioned that it may be inserted easily through the pipe wall opening 14 into the receiving chamber 15. The locking element 2 has a 5 chamfer 21 at its leading end to facilitate its introduction into the pipe wall opening 14 and its passage through the receiving chamber 15. Formed in a set-back manner in its opposite free end is a predetermined breaking point 22 at which the excess length of the locking element 2 is broken off 10 once the chamfer 21 of the free end meets up again with the locking element 2 in the region of the pipe wall opening 14.

Fig.3 shows the installed situation of the socket end 11 of the pipe 1 and of the plug end 12 of the corresponding pipe 1. The free end 111 of the socket end 11 is shown adjoining the 15 locating shoulder 124 of the plug end 12. The region 121 of the plug end 12 and the region 131 of the socket end 11 are precisely adjacent to one another. The location grooves 123, 133 form the receiving chamber 15 for the locking element 2, which is shown inserted into the receiving chamber 15 (cf. 20 Fig.2). The free end 124 of the plug end 12 is shown set back relative to the free end 111 of the socket end 11. Inserted into the receiving space thereby created is the sealing element 3, which is held under tension on the one hand by the free end 124 of the plug end 12 and on the other hand by the 25 locating shoulder 112 of the socket end 11.

Fig.4 shows, in a partial longitudinal section according to Fig.3, a special seat for the sealing ring 3. For said purpose, an insert groove 113 is let in an axial direction into the locating shoulder 112 of the socket end 11. The 30 insert groove 113 is let into the locating shoulder 112 in such a way that there is left, in an inward direction in relation to the clear cross-section of the pipe 1, a residual wall region 114 which is strong enough to take up the maximum compression of the sealing ring. 7 Finally, Fig.5 shows a further possible seat for the sealing ring 3. Here, an insert groove 115 for the sealing ring 3 is introduced in a radial direction into the socket end 11 in the region of the locating shoulder 112. The maximum depth of said insert groove 115 corresponds to the maximum depth of the location groove 133. The free end 124 of the plug end 12 here extends in a bevel 125 directed towards the sealing ring 3.

One effect achieved by the bevel 125 is a pressing of the sealing ring 3 in an axial and radial direction, with an additional effect being a reduction in the force required to deform the sealing ring 3. Owing to the small gap 4 remaining between the locating shoulder 112 of the socket end 11 on the one hand and the opposite free end 124 of the plug end 12, an escape of the sealing ring 3 as a result of unfavourable operating conditions is reliably avoided. At the same time, as a result of said gap 4, the maximum deformation of the sealing ring 3 under compression may be taken up without the free ends 112, 124 touching one another.

Claims

1.CLAIMS Pipe joint for two pipe-jacking pipes or the like, wherein on placing together of the pipes a plug end formed at one end of one of the pipes engages into a socket end formed at one end of the second pipe, the wall thickness of the pipes at the plug end and the socket end being reduced by a radially inward and a radially outward turned step respectively and the height of the step at the plug end matching the height of the step at the socket end, wherein on placing together of the pipes a flexible sealing element is inserted between the free end of the plug end and the adjacent region of the socket end, and wherein at a distance from the free end of the plug end and at a distance from the free end of the socket end location grooves are disposed on the outer periphery of the plug end and on the inner periphery of the socket end respectively, said location grooves upon striking of the free end of the socket end against the locating shoulder formed by the step on the plug end forming a receiving chamber into which, when the pipes are placed together, is let a locking element which is inserted from outside through an opening in the pipe wall, characterized in that the axial length of the stepped region of the plug end (12) is shorter than the axial length of the stepped region of the socket end (11), and that when the pipes (1) are placed together the sealing element (3) is held in a press fit on the one hand by the free end (124) of the plug end (12) and on the other hand by the locating shoulder (112) of the socket end (11). Pipe joint according to claim 1, characterized in that an insert groove (113) for the sealing element (3) is let into the locating shoulder (112) of the socket end (11) in a direction along the pipe axis. Pipe joint according to claim 1, characterized in that, in the region of the locating shoulder (112) of the socket end (11), an insert groove (115) for the sealing element (3) is let in a radial direction into the pipe wall. Pipe joint according to claim 3, characterized in that provided at the free end (124) of the plug end (12) is a wall bevel (125) extending over the periphery. A pipe joint as claimed in any preceding claim substantially as hereinbefore described with' reference to and as illustrated in the accompanying drawings. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS. 10