GB2350082A

GB2350082A - A concrete pipe having a sealing member

Info

Publication number: GB2350082A
Application number: GB9911322A
Authority: GB
Inventors: Robert James Fifer
Original assignee: Stanton Bonna Concrete Ltd
Current assignee: Stanton Bonna Concrete Ltd
Priority date: 1999-05-15
Filing date: 1999-05-15
Publication date: 2000-11-22
Also published as: GB9911322D0; EP1054204A3; EP1054204A2

Abstract

This invention provides a concrete pipe having an annular sealing member 12 anchored in a joint-forming surface thereof; the sealing member 12 having been positioned into a recess 10 in the said joint-forming surface such that it is substantially flush with the said joint-forming surface after moulding, and being anchored in the wall of the pipe by means of an anchoring portion 12b embedded in the surface of the recess; a non-anchoring portion 12a of the annular sealing member 12 having been repositioned after moulding such that it is supported in a position whereby it protrudes from the surface. The pipe is formed by placing the sealing member 12 (figure 4, not shown) about a pallet (figure 3) which is then assembled together with a mould core and an outer mould member. Concrete is poured into the mould which is vibrated to cause compaction. After curing, the non-anchoring portion 12a of sealing member 12 is prised out of recess 10 and a second annular sealing member 14 is snapped into place within the recess 10 behind member 12.

Description

2350082 1 IMPROVEMENTS IN AND RELATING TO SEALS This invention relates to

sealing arrangements, and more particularly to sealing arrangements for concrete pipes.

Concrete pipes typically are formed in lengths having a spigot formation at one end and a socket formation at the other end. Such pipes can be joined together to form pipelines by means of successive spigot and socket joints. In order to prevent leakage from the pipe joints, it is customary to provide a seal around the inner surface of the socket, and a variety of seals have previously been disclosed. Exemplary of known sealing arrangements are the seals described in, for example, GB-A 20033293, GB-A-2108421, DE-A3542427, DE-A3631265, DE-A 3642880, DEA-3900873, DE-A-4025603, DE-A-4112976, DE-A 4133763,DE-A-4134049,DE-A-4315119,EP-A-0077918,EP-A-343677' EP-A-0358256, EP-A-0471319, EP-A-0507005, EP-A-0634532, EP-A 0716260, FR-A-2710085, WO-A-94/05944 and WO-A-94/07073.

One of the problems facing manufacturers and users of concrete pipes is to ensure that when the spigot end is inserted into the socket, the seal is not displaced from its position, but rather forms an effective and complete seal around the circumference of the spigot end of the pipe. However, it is usually difficult to determine visually whether or not a seal has been displaced and consequently with many known sealing systems, there exists the potential for an incorrect or incomplete seal to be formed which would go undetected, thereby resulting in leakage from the pipe joint. In recognition of this problem, it has previously been suggested to anchor the seal in the wall of the concrete pipe, and typically this is achieved by embedding a portion of the seal into the concrete during the 2 moulding operation. Examples of such anchored sealing arrangements are disclosed in many of the patent publications listed above.

Although anchored seals solve the aforementioned problem, the requirement to introduce a seal during the moulding operation introduces complexities into the manufacturing of the pipe and, in particular, means that specially modified moulds and moulding equipment such as pallets (for sockets) and spigot formers (for spigots) may need to be created for a given embedded seal design.

In a typical large scale manufacturing process for making concrete pipes, the pipes can be formed on a pallet and, following the initial moulding operation, the pipe is left on the pallet whilst the concrete cures. Such manufacturing operations require a large number of moulding pallets in order to be able to achieve a required high throughput of moulded pipes. It follows therefore that any change in the seal design, and in particular any attempt to introduce an embedded anchored seal during the moulding process will usually necessitate the production of a large number of new moulding pallets. Thus, in view of the capital cost involved, there is a significant deterrentto investing in the new moulding equipment necessary to produce embedded seal designs. As an alternative to modifying the pallet, various proposals have been made whereby packing rings or spacers have been positioned around the seal during moulding, the removal of the packing rings or spacers after moulding providing the desired surface profile within the socket. However, the use of such packing rings and spacers introduces further complexity and cost into the manufacturing operation.

It is an object of this invention to overcome the aforementioned problems, and to provide a means of manufacturing concrete pipes having anchored seals, without the need to change the pallets conventionally used for concrete pipes, and without the need to use packing rings, 3 spacers and other means for altering the prof i I e of the joint- forming surface of the concrete pipe.

Accordingly, in a first aspect, the invention provides a concrete pipe having an annular sealing member anchored in a joint-forming surface thereof; the anchored sealing member having been moulded into a recess in the said joint-forming surface such that it is substantially flush with the said joint-forming surface after moulding, and being anchored in the wall of the pipe by means of an anc horing portion embedded in the surface of the recess (e.g. towards or at a forward end thereof); a non-anchoring portion of the annular sealing member having been repositioned after moulding such that it is supported in a position whereby it protrudes from the surface.

The non-anchoring portion of the annular sealing member can be repositioned by means of folding or otherwise deforming and is supported in the protruding position by means of a folded or deformed portion of the sealing member. Alternatively, the non-anchoring portion can be repositioned by lifting, or pivoting out of the recess about the anchoring portion, and a second annular sealing member inserted behind and/or beneath the first annular sealing member in order to support it in the protruding position.

Thus, in one embodiment of the invention, there is provided a concrete pipe having first and second annular sealing members anchored in a joint-forming surface thereof; the first anchored sealing member having been moulded into a recess in the said joint-forming surface such that it is substantially flush with the said joint-forming surface after moulding, and being anchored in the wall of the pipe by means of an anchoring portion embedded in the surface of the recess (e.g. towards or at a forward end of the recess); a non-anchoring portion of the first annular sealing member having been lifted out of the recess allowing the 4 placing of the second annular sealing member within the recess behind the first annular sealing member; the second annular sealing supporting the first annular sealing member in a position whereby it protrudes from the surface.

The joint-forming surface is a surface which will typically be in contact with or very close proximity to a surface of another pipe or pipe member to which the concrete pipe is joined. Thus a joint-forming surface is typically a surface in or on which a seal can be mounted for sealing against a surface of another pipe when the concrete pipe and the other pipe are connected together in a spigot and socket joint.

The joint-forming surface can therefore be, for example, a radially inner surface of the socket end of a pipe, or the radially outer surface of the spigot end of a pipe. Preferably however, the joint-forming surface of the pipe is the radially inner surface of the socket end of a pipe.

Thus, in a preferred embodiment, the invention provides a concrete pipe having first and second annular sealing members anchored in a radially inner surface of a socket end of the pipe; the first anchored sealing member having been moulded into a recess in the surface such that it is substantially flush with the said surface after moulding, and being anchored in the surface by means of an anchoring portion embedded in the surface (e.g. towards or at a front end of the recess) such that it is pivotable out of the recess about the said anchoring portion allowing the placing of the second annular sealing member within the recess behind the first annular sealing member; the second annular sealing supporting the first annular sealing member in a position whereby it protrudes radially inwardly from the surface.

The recess within which the first sealing member is disposed, and hence the first sealing member itself, can be of a substantially rectangular shape in cross-section, with exception of the anchoring portion at the forward end of the recess. The second annular sealing member can take the form of a wedge which tapers towards the front of the recess.

However, the shape of the first and second sealing members, and the recess can be varied, provided that the profile of the first sealing member corresponds to the cross-sectional shape of the recess in order that the first sealing member remains flush with the surface of the socket during the manufacturing process.

The first sealing member is formed from an appropriate elastomeric material, for example an ethylene propylene diene monomer (EPDM) rubber or a styrene butadiene rubber (SBR), for example having an IRH hardness in the range from 30 to 55, preferably approximately 45.

The second annular sealing member can also be formed from an elastomeric material, for example an elastomeric material as hereinbefore defined. Alternatively, the second annular sealing member can be formed from a non-elastomeric material, such as a substantially non-elastomeric thermoplastic, in which case the sealing function of the second annular sealing member is to support the first annular sealing member.

However, it is presently preferred that the first and second annular sealing members are both formed of an elastomeric material. As such, the elastomeric materials can be the same or different. Thus, for example, in one embodiment, the first annular sealing member is formed from an elastomer of greater hardness than the second annular sealing member, whereas in another embodiment, the first annular sealing member is formed from an elastomer of lesser hardness than the second annular sealing member.

The first and second annular sealing members can be formed with 6 relatively smooth abutting surfaces such that retention of the second annular sealing member in the recess is effected primarily by means of an edge or lip of the recess engaging an edge of the second sealing member. However, the first and second sealing members can be provided with 5 roughened abutting surfaces so as to increase friction therebetween. Furthermore, the first and second sealing members can be provided, on abutting surfaces thereof, with protrusions and/or recesses or other interlocking formations for inhibiting or preventing dislodgement of the second annular sealing member. Alternatively, or additionally, adhesive may be used to hold the two sealing members together and/or bond the second annular sealing member to the underlying concrete.

In another embodiment, the invention provides a concrete pipe joint formed between a spigot ended concrete pipe and a socket ended concrete pipe, a sealing member (preferably first and second annular sealing members) as hereinbefore defined being arranged radially between the spigot end and socket end and being anchored in one surface thereof whereby a seal is formed therebetween.

In a further embodiment, the invention provides a concrete pipe joint formed between a spigot ended concrete pipe and a socket ended concrete pipe, the socket ended concrete pipe having an annular sealing member (and preferably first and second annular sealing members) as hereinbefore defined disposed in an end thereof, and the spigot end being inserted into the socket end whereby a seal is formed therebetween.

In a still further aspect, the invention provides a process for manufacturing a concrete pipe having a seal embedded therein, the process comprising forming the concrete pipe with a socket or a spigot (preferably a socket) having a first annular sealing member anchored in a wall thereof, the first annular sealing member being moulded into a recess into the pipe wall such as it is substantially flush therewith and, after 7 moulding, pivoting the first annular sealing member forwardly about an anchoring portion embedded in the concrete towards a front end of the recess, and positioning a second annular sealing member behind and radially outwardly of the first sealing member, the second sealing member being retained within the recess, such that the first annular sealing member is supported in a configuration whereby it protrudes from the pipe wall, (e.g. into the bore of the socket).

In another aspect, the invention provides a process for manufacturing a concrete pipe having a seal embedded therein, the process comprising forming the concrete pipe with a socket or a spigot (preferably a socket) having an annular sealing member anchored in a wall thereof, the first annular sealing member being moulded into a recess into the pipe wall such as it is substantially flush therewith and, after moulding, repositioning a non-anchoring portion of the annular sealing member and supporting the annular sealing member in a configuration whereby it protrudes from the pipe wall, (e.g. into the bore of the socket).

In a still further aspect, the invention provides a method of manufacturing a concrete pipe having first and second annular sealing members embedded therein as hereinbefore defined, the process comprising placing a first annular sealing member having a sealing portion and an anchoring portion about a pallet portion of a mould such that the anchoring portion is oriented towards the outer end of the pallet; placing an outer mould member and inner mould core about the pallet and pouring a concrete mix into the assembled mould to form a concrete pipe shape; removing the outer mould and inner core to leave the pipe mounted on the pallet; allowing the pipe to cure and then removing the pipe from the pallet; prising the seal out of the recess such that it pivots about the anchoring portion, and positioning a second annular sealing member behind the first annular sealing member and within the recess such that the first annular sealing member protrudes from the radially inwardly of the 8 socket wall.

After moulding of the pipe has taken place, the first annular sealing member is substantially flush with the surface of the pipe wall into which it has been moulded. A suitable tool is then used to prise the sealing member out of the recess so that the second sealing member can be snapped into place. As an alternative, or in addition, to using a tool, means may be provided for assisting removal of the sealing member from the recess. Such removal means can take the form of, for example, a string or tape placed between the wall of the recess and the sealing member and having an end protruding such that pulling on the string or tape has the effect of pulling the sealing member out of the recess. Such a string or tap would be positioned about the sealing member on the pallet prior to moulding taking place.

Although it is presently preferred that a second annular sealing member is used to support the first annular sealing member in a position whereby it protrudes from the surface of the pipe, the sealing member could be supported in a protruding position by virtue of being folded or deformed, a folded or deformed portion serving as the support. In such as case, the second annular sealing member could be omitted. In order to enable the folded portion of the sealing member to provide the necessary support, the floor of the recess can, for example, be provided with ridges, ledges or other protrusions or indentations which can engage the folded portion of the sealing member to hold it In place.

The invention will now be illustrated by reference to the accompanying drawings of which:- Figure 1 is a sectional elevation through a socket end of a concrete pipe fitted with a seal according to one embodiment of the invention; Figure 2 is a partial sectional elevation of the socket end of Figure 1 after moulding and removal of a mould pallet, but prior to insertion of a 9 second sealing member; Figure 3 is a side elevation of a pallet used in the manufacture of the concrete pipes of Figures 1 and 2; and Figure 4 is a sectional elevation through a first sealing member prior 5 to moulding into the pipe wall.

As shown in Figure 1, a concrete pipe according to the invention has a socket end 2 having an enlarged bore region 4 relative to the main bore 6 of the pipe. The socket has a radiused front edge 8 behind which is formed a recess 10. Disposed within the recess Is a sealing arrangement comprising a first seal member 12 and a second seal member 14. The first sealing member 12 has a sealing portion 1 2a of generally rectangular cross-section, and an anchoring portion 12b which in this embodiment is of substantially circular cross-section (although it could of course be of a different shape in cross section, such as rectangular or other regular or irregular polygonal shape, for example). The anchoring portion 1 2b is embedded in the concrete at the leading or forward end of the recess 10. Held within the recess behind the first sealing member is the second sealing member 14 which is generally wedge-shaped at the forward end 14a thereof and tapers at its rear end 14b. The first and second sealing members 12, 14 in this embodiment are both formed from an ethylene propylene diene monomer (EPDM) rubber having an IRD hardness of approximately 45.

The concrete pipe and moulded in seal are moulded on a pallet having the general shape shown in Figure 3. A pallet of this shape can be used to form conventional concrete pipes without moulded in seals. In order to form the pipes of the invention, a sealing member of the profile shown in Figure 4 is placed about the pallet which is then assembled together with a mould core and outer mould member in conventional fashion. Concrete is then poured into the mould which is subjected to vibration to effect compaction. In this embodiment, the pipe is formed from a relatively dry mix which means that immediately after moulding it is capable of being self supporting, and hence the inner mould core and outer mould member are removed, thereby allowing the uncured pipe to be removed from the moulding machine on its pallet. The pipe is thereafter left on the pallet whilst curing takes place to an extent sufficient to allow the dimensions of the pipe to remain stable, and to allow handling. A pipe thus formed has a socket end as shown in Figure 2, in which the first sealing member is embedded in the concrete wall and lies in the recess 10 so as to be substantially flush with the wall of the socket.

Thereafter, the first sealing member can be prised out of the recess 10 using a suitable tool such that it pivots about the anchoring portion 1 2b at the forward end of the recess. The second annular sealing member 14 can then be snapped into place within the recess behind the first sealing member 12. The resilience of the first sealing member and the restoring force towards the recess, serve to hold the second annular sealing member in place. However, as further means of retaining the second sealing member in place, the first and second sealing members could be bonded together by means of a suitable adhesive if required and/or the second sealing member can be adhesively bonded to the underlying concrete.

However, this is less preferred, and in any event should be unnecessary.

In the foregoing embodiment, the production of the concrete pipe makes use of a relatively dry concrete mix. It will be appreciated however that the invention could also be applied to methods of casting concrete pipes using a wet concrete mix, although in such methods the pipes would typically e left longer to cure before removing from the moulds.

It will readily be apparent that numerous modifications and alterations can be made to the pipes and sealing assemblies shown in the accompanying drawings without departing from the principles underlying this invention; and all such modifications and alterations are intended to be embraced by this application.

Claims

1 A concrete pipe having an annular sealing member anchored in a joint-forming surface thereof; the anchored sealing member having been moulded into a recess in the said joint-forming surface such that it is substantially flush with the said joint-forming surface after moulding, and being anchored in the wall of the pipe by means of an anchoring portion embedded in the surface of the recess; a non-anchoring portion of the annular sealing member having been repositioned after moulding such that it is supported in a position whereby it protrudes from the surface.

2. A concrete pipe according to claim I wherein the non-anchoring portion of the annular sealing member is repositioned by means of folding or otherwise deforming and is supported in the protruding position by means of a folded or deformed portion of the sealing member.

3. A concrete pipe according to claim 1 wherein the non-anchoring portion is repositioned by lifting, or pivoting out of the recess about the anchoring portion, and a second annular sealing member inserted behind and/or beneath the first annular sealing member in order to support it in the protruding position.

4. A concrete pipe having first and second annular sealing members anchored in a joint-forming surface thereof; the first anchored sealing member having been moulded into a recess in the said joint-forming surface such that it is substantially flush with the said joint-forming surface after moulding, and being anchored in the wall of the pipe by means of an anchoring portion embedded in the surface of the recess (e.g.

towards or at a front end of the recess); a non-anchoring portion of the first annular sealing member having been lifted out of the recess allowing the placing of the second annular sealing member within the recess behind 12 the first annular sealing member; the second annular sealing supporting the first annular sealing member in a position whereby it protrudes from the surface.

5. A concrete pipe according to any one of the preceding claims wherein the joint-forming surface is a radially inner surface of the socket end of a pipe, or the radially outer surface of the spigot end of a pipe.

6. A concrete pipe according to claim 5 wherein the joint-forming surface of the pipe is the radially inner surface of the socket end of a pipe.

7. A concrete pipe having first and second annular sealing members anchored in a radially inner surface of a socket end of the pipe; the first anchored sealing member having been moulded into a recess in the surface such that it is substantially flush with the said after moulding, and being anchored in the surface by means of an anchoring portion embedded in the surface towards or at a front end of the recess such that it is pivotable out of the recess about the said anchoring portion allowing the placing of the second annular sealing member within the recess behind the first annular sealing member; the second annular sealing supporting the first annular sealing member in a position whereby it protrudes radially inwardly from the surface.

8. A concrete pipe according to any one of the preceding claims wherein the recess within which the first annular sealing member is initially disposed is of a substantially rectangular shape in cross- section.

I

9. A concrete pipe according to any one of claims 3 to 8 wherein there is present a second annular sealing member in the form of a wedge which 30 tapers towards the front of the recess.

10. A concrete pipe according to any one of the preceding claims 13 wherein the annular sealing member(s) are formed of an elastomeric material.

11. A concrete pipe according to claim 10 wherein both first and second annular sealing members are present and the first annular sealing member is formed from an elastomer of greater hardness than the second annular sealing member.

12. A concrete pipe according to claim 10 wherein both first and second annular sealing members are present and the first annular sealing member is formed from an. elastomer of lesser hardness than the second annular sealing member.

13. A concrete pipe according to claim 7 wherein both first and second annular sealing members are present and the first and second annular sealing members are formed from elastomeric materials having the same hardness, and, for example are formed from the same material.

14. A concrete pipe substantially as described herein with reference to the accompanying drawings.

15. A concrete pipe joint formed between a spigot ended concrete pipe and a socket ended concrete pipe, an annular sealing member (preferably first and second annular sealing members) as defined in any one of the preceding claims being arranged radially between the spigot end and socket end and being anchored in one surface thereof whereby a seal is formed therebetween.

16. A concrete pipe joint formed between a spigot ended concrete pipe and a socket ended concrete pipe, the socket ended concrete pipe having an annular sealing member (preferably first and second annular sealing members) as defined in any one of claims 1 to 14 disposed in an end 14 thereof, and the spigot end being inserted into the socket end whereby a seal is formed therebetween.

17. A concrete pipe joint substantially as described herein with 5 reference to the accompanying drawings.

18. A process -for manufacturing a concrete pipe having a seal embedded therein, the process comprising forming the concrete pipe with a socket or a spigot (preferably a socket) having a first annular sealing member anchored in a wall thereof, the first annular sealing member being moulded into a recess into the pipe wall such as it is substantially flush therewith and, after moulding, pivoting the first annular sealing member forwardly about an anchoring portion embedded in the concrete (e.g. towards a front end of the recess), and positioning a second annular sealing member behind and radially outwardly of the first sealing member, the second sealing member being retained within the recess, such that the first annular sealing member is supported in a configuration whereby it protrudes from the pipe wall, (e.g. into the bore of the socket).

19. A process for manufacturing a concrete pipe having a seal embedded therein substantially as described herein with reference to the accompanying drawings.

20. A method of manufacturing a concrete pipe having first and second annular sealing members embedded therein as defined in any one of claims 1 to 14, Ihe process comprising placing a first annular sealing member having a sealing portion and an anchoring portion about a pallet portion of a mould such that the anchoring portion is oriented towards the outer end of the pallet; placing an outer mould member and inner mould core about the pallet and pouring a concrete mix into the assembled mould to form a concrete pipe shape; removing the outer mould and inner core to leave the pipe mounted on the pallet; allowing the pipe to cure and then removing the pipe from the pallet; prising the seal out of the recess such that it pivots about the anchoring portion, and positioning a second annular sealing member behind the first annular sealing member and within the recess such that the first annular sealing member protrudes from the 5 radially inwardly of the socket wall.

21. A method of manufacturing a concrete pipe having first and second annular sealing members embedded therein substantially as described herein with reference to the accompanying drawings.