GB2217418A - A conduit section with plastics coupling rings - Google Patents

Abstract

The section has two end portions, each adapted for connection to an end portion of another said section. For the connection of two said sections (1, 11, 21, 31, 41; 2, 12, 22, 32, 42) at their adjacent end portions, the first section has a first end portion provided with a first moulding (4, 14, 24, 34, 44) and the second section has a second end portion provided with a second moulding (3, 13, 23, 33, 43). Each said moulding is in the form of ring-shaped profiled moulding or extrusion of synthetic plastics and is fixed to the respective end portion during the manufacture of the relevant section or subsequently. <IMAGE>

Description

CONDUIT SECTIONS The invention relates to conduit sections, particularly precast conduit sections of concrete, and to means for their connection and sealing.

Sections of this type are used in sewers, drains, pipes, ducting and tunnels.

Traditionally precast concrete components have been jointed by one of the following methods: 1. sliding rubber rings of circular or shaped profile; 2. rolling rubber rings of circular or shaped profile; 3. mastic type sealants of a butyl or biu- mastic type base; 4. expanding chemical substances; or 5. combinations of these.

The shortcomings and disadvantages of these jointing methods are well-known to persons skilled in the art. The design limitations of these methods and joints reside in the joint profiles obtainable using casting methods, together with the tolerances achievable. In addition the quality and finish of the jointing surfaces normally requires 2 finishing operation when the component is demoulded. This is especially so in the case of sockets which are "dressed" with a sand/cement mortar to smooth over the coarse aggregate. The majority of concrete pipes are cast with a bell end. This is to maintain the required wall thickness to prevent leakage of water through the concrete when it is subjected to internal or external water pressure. This feature requires additional concrete, a wider trench, care when laying and limits the manner of storage and handling.

Generally the adjacent ends of two pipes to be connected together are provided in addition to one or two transverse surfaces also with a substantially longitudinal extending surface and between the two adjacent longitudinal surfaces of the adjacent ends is inserted at least one sealing ring. Because the surfaces in contact with the sealing ring or rings are rough, and may be porous, the sealing provided by the sealing ring or rings is imperfect so that water and other liquids can escape from or infiltrate into the pipe. This can be minimised by the use of relatively large section sealing rings under high compression. However, this solution has performance limitations under shear loads and/or high internal water pressures. Also the current methods of jointing do not protect the jointing surfaces from sulphate attack.This is an increasingly important aspect especially in areas with restrictions on the use of water.

The aim of the invention is to avoid or at least to mitigate the disadvantages.

This is achieved according to the invention in thatat least a portion of the adjacent surfaces of two sections to be connected together are provided with a synthetic plastics moulding or extrusion which is fixed to the respective end surfaces either during their manufacture or subsequently.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, each of which is a longitudinal section through a portion of the adjcent ends of two pipes being connected together. In the drawings: Figure 1 shows a first embodiment; Figure 2 shows a second embodiment; Figure 3 shows a third embodiment; Figure 4 shows a fourth embodiment; and Figure 5 shows a fifth embodiment.

The first embodiment, shown in Figure 1, is a connection of a pipe 1 with a spigot end to a pipe 2 with a socket end. To a part of the inside surface of the socket is connected a ring-shaped synthetic plastics moulding 3 which extends partly along a longitudinal surface and partly along a transverse surface of the socket. Also to the spigot is connected a ring-shaped synthetic plastics moulding 4 which extends partly along a longitudinal surface and partly along a the transverse surface of the spigot. The last mentioned moulding t has an annular recess 5 which in the illustrated example receives a sealing ring 6 of a substantially wedgeshaped cross-section.

Figure 2 shows a connection of two pipes 11, 12 having substantially step-shaped butt ends.

One longitudinal and one transverse face of each end is provided with a moulding 13, 14 of the type described and one of the mouldings 14 has a recess 45 for receiving a sealing ring 16 which in the illustrated example is of a circular cross-section.

In the embodiment shown in Figure 2 both ends of each of the mouldings used are hook-shaped and the hooks 13A, 13B; 14A, 143 are surrounded by concrete during the casting process.

Fig#ure 3 shows two butt ends of two pipes 21, 22. In both ends is provided an outer peripheral recess. The recess of the pipe 22 is relatively shallow and houses a substantially tubular moulding 23 which extends beyond the pipe. The other pipe 21 has a stepped peripheral recess in the end portion of which is provided a relatively short annular moulding 24. In the moulding 24 is a recess 25 for receiving a sealing ring 26.

Figure 4 shows an embodiment similar to that shown in Figure 3 in that one pipe 32 has a moulding 33 which projects beyond its ends and the other pipe 31 has a moulding 34 having two peripheral recesses 35, 35A each housing one sealing ring 36, 36A. While in the embodiments according to Figures 1, 2 and 3 there was always a gap between the transverse faces, in Figure 2 there was substantially only one moulding along each transverse face and in Figure 3 there was no moulding along the transverse faces, in the fourth embodiment mouldings are provided along both adjacent transverse faces of the pIpes 31, 32 being connected. The moulding 33, 34 have each extensions received in recesses provided in the pipe ends.

The end face of the pipe 32 is provided with several (eg. eight) angularly spaced apart ribs 38 which strengthen the pipe 32 and also give a positive minimum joint gap between the mouldings 33 and 34 when the joint is assembled. In the forth embodiment both the pipes 31, 32 are provided with internal linings 39 which form continuation of the internally situated portions of the mouldings 33, 34.

In this way a pipe line is obtained which is totally protected from sulphate attack.

The fifth embodiment shown in Fig. 5 illustrates a connection of two pipes 41, 42 provided, respectively, with mouldings 43, 44. It differs from the fourth embodiment in that the moulding 44 on the pipe 41 has a longitudinal portion which projects beyond the end face of the adjacent pipe 42, but this longitudinal portion is situated on the inner rather than the outer side of the pipes.

The moulding 43 is stepped to delimit between the stepped portion of the moulding 43 and the longitudinal portion of the moulding 44 a first annular gap 45 in which is situated a substantially wedge-shaped sealing ring 46. At their outer ends the mouldings 43, 44 delimit a second annular gap d7 for a secondary sealing ring 48 of a substantially circular cross-section. This embodiment is suitable for pipe checking where the transverse portions 4Q, 49A of the mouldings 41, 42 act to transmit longitudinal loads without "spalling" the concrete from which the pipes 41, 42 are made.

A further useful feature of the fifth embodiment is that the inner portion of the pipe A2 has a substantially U-shaped end 50 open towards the pipe 41. The longitudinal portion of the moulding 44 has a tapering end 51 received in the annular space defined by the U-shaped end 50 to give a smooth bore even after significant angular deflection of the pipes 41, 42 relative to the other. Also in this embodiment both the pipes 41, 42 are provided with internal lining 52 which forms continuation of the adjacent portions of the mouldings 43, 46.

The invention has a number of advantages which include the following: (a) Positive prevention of leakage through the concrete in the joint area.

(b) Protection of the jointing surfaces from sulphate attack.

(c) Protection of the joints from damage in handling and alignment.

(d) Improving the tolerances achieveable and therefore increasing the performance of the joint.

(e) Eliminating the need to perform finishing work on sockets and spigots after demoulding.

(f) Reducing the wear on moulds and forming rings.

(g) Reducing the size of elastomer needed.

(h) Permitting the design of joints with low insertion forces improved performance in terms of internal and external pressure resistance, shear, draw and angular deflection.

(i) Permitting the design of joints with predetermined joint gap.

(j) Permitting the design of joints with factory fitted sealing rings.

(k) Permitting the design of joints with retained and/or lip seals.

(l) Existing moulds and casting to be used with, or without, modification.

(m) Permitting the design of a joint which will limit deflection under a low shear load but will remain flexible under high loads.

(n) Eliminate the need for belled sockets reducing cost of concrete, transport, trenching and laying.

Claims (9)

1. A conduit section having two end portions, each adapted for connection to an end portion of another said section, wherein for the connection of two said sections at their adjacent end portions, the first section has a first end portion provided with a first moulding and the second section has a second end portion provided with a second moulding, each said moulding being in the form of ring-shaped profiled moulding or extrusion of synthetic plastics and being fixed to the respective end portion during the manufacture of the relevant section or subsequently.

2. A conduit section according to Claim 1, wherein the first moulding has a portion providing an annular recess or gap for accommodating a sealing ring, and the second moulding has a portion which on connection of the two sections is in sealing contact with the sealing ring.

3. A conduit section according to Claim 2, wherein the said moulding portions are elongate and extend substantially longitudinally with respect to the sections being connected.

4. A conduit section according to any one of Claims 1 to 3, wherein at least one end of at least one of said mouldings is hook-shaped.

5. A conduit section according to Claim 2 or any claim appended thereto, wherein the second moulding has a portion projecting beyond the end portion by which it is carried, said portion being the portion in sealing contact with the sealing ring.

6. A conduit section according to Claim 2 or any claim appended thereto, wherein the first moulding has a portion projecting beyond the end portion by which it is carried and extending along the second moulding, the second moulding and said projecting portion of the first moulding defining a gap for accommodating a sealing ring.

7. A conduit section according to any one of the preceding claims, wherein each of the mduldings has at least one substantially longitudinal portion and one transverse portion.

8. A conduit section according to Claim 1, constructed, arranged and adapted to operate substantially as herein described with reference to, and as shown in, the accompanying drawings.

9. A conduit composed of conduit sections according to any one of the preceding claims.