GB1586862A

GB1586862A - Pipe joints

Info

Publication number: GB1586862A
Application number: GB3095176A
Authority: GB
Original assignee: McAlpine and Co Ltd
Current assignee: McAlpine and Co Ltd
Priority date: 1976-07-24
Filing date: 1976-07-24
Publication date: 1981-03-25
Also published as: BE857078A; NL7708173A

Description

(54) IMPROVEMENTS IN AND RELATING TO PIPE JOINTS (71) We, MCALPINE & COMPANY LIMITED, a British Company, of Kelvin Avenue, Hillington, Glasgow G52 4LF, Scotland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to pipe joints and particularly but not exclusively to pipe joints formed between two pipe units of synthetic plastics material.

It is common practice when two pipes have to be connected sealingly together to provide the end of one of the pipe sections with an end socket of slightly greater diameter than the diameter of the pipe. Within the socket a groove or other abutment is formed in the inside surface of the socket to retain an O-ring thereagainst. It is usual for the end of the other pipe section which is to be inserted into the socket, to be chamfered. When the two pipe sections are to be connected together, the chamfered pipe section is merely inserted into the end socket of the other pipe section to an extent such that the O-ring in the socket is sealed against the outer surface of the inserted section.

The aforesaid arrangement has a significant disadvantage in that on inserting the chamfered section into the pipe socket of the other section the O-ring is engaged by the inserted end and there is a tendency for the O-ring to be rolled or otherwise pushed out of its intended location. The result is that the fitting of the two sections has to be effected once again after replacing the O-ring seal or alternatively the sections are fitted together without a proper seal being made.

An object of the present invention is to provide a coupling socket for a spigot-andsocket pipe coupling of the type incorporating a sealing ring in which the sealing ring is restrained against movement out of position on insertion of one pipe section into the other.

According to the present invention there is provided a coupling socket for receiving one end of a second pipe section which has a predetermined outside diameter to form a spigot-and-socket pipe coupling, said coupling socket comprising a first pipe sectionas defined hereinbelow said first pipe section having an end provided with an annularly radially inwardly extending stop means and an annularly radially inwardly extending deformable wedge means, said stop means having a predetermined minimum internal diameter for disposal therethrough of said one end of the second pipe section, said wedge means having an inner end surface disposed opposite said stop means for defining a groove therebetween, and a radially inner wedge surface inclined towards the central axis of said first pipe section towards the said inner end surface; and a resiliently deformable sealing ring disposed in said groove, said radially inner wedge surface having a predetermined minimum internal diameter less than said predetermined minimum internal diameter of the stop means and said sealing ring having a minimum internal diameter similar to that of said predetermined minimum internal diameter of said radially inner wedge surface, such that said sealing ring is substantially shielded from the inserted end of the second pipe section during insertion thereof in use of the coupling socket, whilst permitting sealing contact between the sealing ring and the outside of the second pipe section in its fully inserted position, and said wedge means having a predetermined minimum internal diameter relative to that of said stop means and being formed and arranged and said inner end surface of the wedge means being disposed at an angle to the central axis of the first pipe section, such that upon insertion of the end of a said second pipe section having a predetermined outside diameter greater than the predetermined minimum internal diameter of the wedge means but not greater than said predetermined minimum internal diameter of said stop means, in use of the coupling socket, the end of said second pipe section engages said inner wedge surface and deforms the wedge means radially outwards with displacement of its inner end surface against the sealing ring so as to securely clamp said sealing ring in said groove whereby said sealing ring is substantially shielded from and held against displacement by the end of the second pipe section during insertion of the second pipe section end.

As used herein the expression "pipe section" indicates either a simple pipe or part of a more complex body which includes a pipe with a free end for coupling to another pipe section.

By providing a wedge means disposed so that it substantially shields the sealing ring from the end of the second pipe section during the latter's insertion, damage to or displacement of the sealing ring during pipe connection is substantially avoided whilst still retaining good sealing between the sealing ring and the inserted pipe section upon completion of insertion.

An embodiment of the invention will now be described by way of example, with reference to the accompanying drawing which shows a longitudinal sectional view of one form of pipe joint of the invention.

A first pipe section 1 is synthetic plastics material is provided at one end with a radially enlarged coupling socket 2. A second pipe section 3 having a predetermined outside diameter and which may also be of synthetic plastics material is shown in a position ready for insertion into the socket 2 of the first section 1 so that the two sections 1 and 3 are sealingly connected together.

In order to effect this sealing, the free end of the socket 2 is undercut in its internal surface to define a terminal skirt 5 and to provide an annular stop means in the form of a shoulder having an annular surface 4 inclined towards the central axis of the socket in the direction away from the open end of the socket and having a predetermined minimum internal diameter corresponding to the internal diameter of the socket 2 inwardly of said stop means surface 4 which is in turn substantially equal to the predetermined outside diameter of the second pipe section 3. The socket 2 also is formed with an annular projection 6 which extends radially outwardly beyond the skirt 5.

A resiliently deformable scaling ring 7 of neoprene or other similar suitable material is located against the undercut surface 4 and is retained in position thereagainst by a wedge means incorporated in an annular cap 8 of synthetic plastics material which is fitted around the free end of skirt 5 as shown in the drawing. It will be seen that the cap 8 has, in section, a longer limb which extends about the outer surface of the skirt 5 and into engagement with the adjacent annular projection 6 at the free end of the limb. The other limb of the cap 8 is wedgeshaped in cross section as can also be seen from the drawing and the free end of said other limb is undercut to provide an inner end surface 9 which is inclined towards the central axis of the socket in the direction away from the stop means 4 and which extends away from the free end of the pipe socket 2 so that its outermost portion (relative to the interconnected ends of the limbs) substantially overlies one end of the sealing ring 7, the minimum internal diameter of the inner end surface 9 being approximately equal to the internal diameter of the sealing ring 7 and slightly smaller than said predetermined minimum internal diameter of the stop means 4. A radially inner wedge surface 12 is inclined towards the central longitudinal axis of the pipe in the direction from the adjacent free end of the pipe 1 to its other end, i.e. towards the inner end surface 9.

In the embodiment shown, the cap 8 is merely press fitted over two retaining beads 10 on the outer surface of the skirt 5 but it will be readily understood that any other suitable means for locating the cap on the end of the socket can equally well be employed. For example the cap can be screwed or welded on to or into the end of the socket. Conveniently the cap is releasably secured on the end of the socket.

When it is desired to connect the pipe sections 1 and 3 together, one end of the second pipe section 3 is simply pushed into the socket 2 of the section 1. As the inserted end of the second pipe section 3 enters the socket 2 it first engages the second inner wedge surface 12 of the cap 8 and deforms the other limb thereof radially outwardly so that the inner end surface 9 is pressed against the sealing ring 7 to clamp it fixedly within a retaining undercut groove, defined between the stop means surface 4 of the socket 2 and the inner end surface 9 of the wedge means 8, during insertion of the second pipe section 3. As may be readily seen in the drawings, when the wedge-shaped limb of the cap is deformed radially outwardly the inclined inner end surface 9 in turn exerts a force having a radially outwardly directed component on the sealing ring 7 compressing it against the base of the groove in which it is sealed as the smallest internal diameter of the inner end surface 9 is increased, and before the end of the second pipe section 3 reaches the sealing ring 7. Thus when the inserted end of said second pipe section 3 reaches the sealing ring 7 the wedge shaped limb of the cap 8 tends to protect the sealing member 7 from clamaae such ns that enconntered on inaPr- tion of the pipe section by the substantial inter-engagement between the sealing member and the pipe section which arises in prior art designs in which the sealing member has a relatively large unshielded radially inwardly projecting portion.

It will also be appreciated that due to the presence of the wedge-shaped limb of the cap 8 correct alignment of the pipe section 3 with the pipe section 1 upon insertion of the former into the latter is significantly facilitated.

The above described embodiment has been found to be one suitable form of the invention but it will be understood that various modifications can be made thereto. For example it is not necessary that the first pipe section 1 should have an enlarged diameter socket 2 as shown. The present invention can equally well be embodied in a constant diameter pipe provided that the diameter of the second pipe section 3 is compatible with insertion into the end of the constant diameter pipe. Also it is not essential to locate the sealing ring 7 against an undercut surface 4 so long as some stop means is provided for preventing movement of the sealing ring 7 along the line of the pipe section 1 on insertion of the other pipe section.

It is also possible for the cap 8 to be formed integrally with the free end of the pipe section 1 or its socket 2 but in general it is desirable for ease of manufacture that the cap should be a separate integer. It will also be understood that the cross section of the sealing ring 7 can be of any suitable shape and not necessarily the particular cross section as shown in the drawing and in which the sealing ring tapers radially inwards from the outer peripheral surface and is formed with a peripherally extending groove on its inner peripheral surface, provided however that its smallest internal diameter corresponds substantially to that of the wedge-shaped limb of the cap.

The pipe sections and cap are preferably of synthetic plastics material such as polyethylene, polypropylene, polyvinyl chloride, or acrylonitrile-butadiene-styrene copolymer but can be of any suitable material so long as the wedge portion is sufficiently deformable to effect the necessary locking or clamping action on the sealing member.

If desired, the wedge-shaped limb of the cap 8 may be reduced in thickness so that it will deform substantially toward the sealing ring 7 as the pipe section 3 is inserted into the socket 2. This helps to ensure good sealing around the pipe section 3.

WHAT WE CLAIM IS:- 1. A coupling socket for receiving one end of a second pipe section which has a predetermined outside diameter to form a spigot-and-socket pipe coupling, said coupling socket comprising a first pipe section as defined hereinbefore said first pipe section having an end provided with an annularly radially inwardly extending stop means and an annularly radially inwardly extending deformable wedge means, said stop means having a predetermined minimum internal diameter for disposal therethrough of said one end of the second pipe section, said wedge means having an inner end surface disposed opposite said stop means for defining a groove therebetween, and a radially inner wedge surface inclined towards the central axis of said first pipe section towards the said inner end surface; and a resiliently deformable sealing ring disposed in said groove, said radially inner wedge surface having a predetermined minimum internal diameter less than said predetermined minimum internal diameter of the stop means and said sealing ring having a minimum internal diameter similar to that of said predetermined minimum internal diameter of said radially inner wedge surface, such that said sealing ring is substantially shielded from the inserted end of the second pipe section during insertion thereof in use of the coupling socket, whilst permitting sealing contact between the sealing ring and the outside of the, second pipe section in its fully inserted position, and said wedge means having a predetermined minimum internal diameter relative to that of said stop means and being formed and arranged and said inner end surface of the wedge means being disposed at an angle to the central axis of the first pipe section, such that upon insertion of the end of a said second pipe section having a predetermined outside diameter greater than the predetermined minimum internal diameter of the wedge means but not greater than said predetermined minimum internal diameter of said stop means, in use of the coupling socket, the end of said second pipe section engages said inner wedge surface and deforms the wedge means radially outwards with displacement of its inner end surface against the sealing ring so as to securely clamp said sealing ring in said groove whereby said sealing ring is substantially shielded from and held against displacement by the end of the second pipe section during insertion of the second pipe section end.

2. A coupling socket as claimed in Claim 1, in which the inner end surface of the wedge means is inclined towards the central axis of the socket in the direction away from the stop means whereby the inner end surface of the wedge means is displaced radially outwards and towards the stop means upon insertion of said second pipe section.

3. A coupling socket as claimed in Claim 1 or Claim 2, in which the wedge means is formed integrally with said end of the first pipe section.

4. A coupling socket as claimed in Claim 1 or Claim 2, in which the wedge means is in the form of a discrete member separate from said end of the first pipe section.

5. A coupling socket as claimed in Claim

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. presence of the wedge-shaped limb of the cap 8 correct alignment of the pipe section 3 with the pipe section 1 upon insertion of the former into the latter is significantly facilitated. The above described embodiment has been found to be one suitable form of the invention but it will be understood that various modifications can be made thereto. For example it is not necessary that the first pipe section 1 should have an enlarged diameter socket 2 as shown. The present invention can equally well be embodied in a constant diameter pipe provided that the diameter of the second pipe section 3 is compatible with insertion into the end of the constant diameter pipe. Also it is not essential to locate the sealing ring 7 against an undercut surface 4 so long as some stop means is provided for preventing movement of the sealing ring 7 along the line of the pipe section 1 on insertion of the other pipe section. It is also possible for the cap 8 to be formed integrally with the free end of the pipe section 1 or its socket 2 but in general it is desirable for ease of manufacture that the cap should be a separate integer. It will also be understood that the cross section of the sealing ring 7 can be of any suitable shape and not necessarily the particular cross section as shown in the drawing and in which the sealing ring tapers radially inwards from the outer peripheral surface and is formed with a peripherally extending groove on its inner peripheral surface, provided however that its smallest internal diameter corresponds substantially to that of the wedge-shaped limb of the cap. The pipe sections and cap are preferably of synthetic plastics material such as polyethylene, polypropylene, polyvinyl chloride, or acrylonitrile-butadiene-styrene copolymer but can be of any suitable material so long as the wedge portion is sufficiently deformable to effect the necessary locking or clamping action on the sealing member. If desired, the wedge-shaped limb of the cap 8 may be reduced in thickness so that it will deform substantially toward the sealing ring 7 as the pipe section 3 is inserted into the socket 2. This helps to ensure good sealing around the pipe section 3. WHAT WE CLAIM IS:-

1. A coupling socket for receiving one end of a second pipe section which has a predetermined outside diameter to form a spigot-and-socket pipe coupling, said coupling socket comprising a first pipe section as defined hereinbefore said first pipe section having an end provided with an annularly radially inwardly extending stop means and an annularly radially inwardly extending deformable wedge means, said stop means having a predetermined minimum internal diameter for disposal therethrough of said one end of the second pipe section, said wedge means having an inner end surface disposed opposite said stop means for defining a groove therebetween, and a radially inner wedge surface inclined towards the central axis of said first pipe section towards the said inner end surface; and a resiliently deformable sealing ring disposed in said groove, said radially inner wedge surface having a predetermined minimum internal diameter less than said predetermined minimum internal diameter of the stop means and said sealing ring having a minimum internal diameter similar to that of said predetermined minimum internal diameter of said radially inner wedge surface, such that said sealing ring is substantially shielded from the inserted end of the second pipe section during insertion thereof in use of the coupling socket, whilst permitting sealing contact between the sealing ring and the outside of the, second pipe section in its fully inserted position, and said wedge means having a predetermined minimum internal diameter relative to that of said stop means and being formed and arranged and said inner end surface of the wedge means being disposed at an angle to the central axis of the first pipe section, such that upon insertion of the end of a said second pipe section having a predetermined outside diameter greater than the predetermined minimum internal diameter of the wedge means but not greater than said predetermined minimum internal diameter of said stop means, in use of the coupling socket, the end of said second pipe section engages said inner wedge surface and deforms the wedge means radially outwards with displacement of its inner end surface against the sealing ring so as to securely clamp said sealing ring in said groove whereby said sealing ring is substantially shielded from and held against displacement by the end of the second pipe section during insertion of the second pipe section end.

5. A coupling socket as claimed in Claim

4, in which the wedge means is embodied in an annular cap having a transverse crosssection comprised by a first wedge-shaped limb interconnected to an outer limb to define a groove therebetween for receiving a respective portion of said end of the first pipe section.

6. A coupling socket as claimed in Claim 5, in which the cap is releasably secured to said end of the first pipe section.

7. A coupling socket as claimed in any one of the preceding claims, in which the wedge means is of a deformable synthetic plastics material.

8. A coupling socket as claimed in any one of the preceding claims, in which the annular stop means is in the form of an annular stop surface inclined towards the central axis of the socket in the direction away from the wedge means.

9. A coupling socket as claimed in any one of the preceding claims in which the stop means is in the form of a shoulder.

10. A coupling socket as claimed in any one of the preceding claims in which the sealing ring tapers radially inwards from its outer peripheral surface and is formed with a peripherally extending groove on its inner peripheral surface.

11. A coupling socket for a spigot-andsocket coupling according to claim 1 substantially as described hereinbefore with particular reference to the accompanying drawing.