GB1600725A

GB1600725A - Pipe socket assembly

Info

Publication number: GB1600725A
Application number: GB24489/78A
Authority: GB
Original assignee: Everitube SA
Current assignee: Everite SA
Priority date: 1977-07-01
Filing date: 1978-05-30
Publication date: 1981-10-21
Also published as: IT7853471V0; BE868662A; FR2396233B1; LU79883A1; IT7868540A0; DE7819692U1; FR2396233A1

Description

(54) IMPROVEMENTS IN OR RELATING TO A PIPE SOCKET ASSEMBLY (71) We, EVERITUBE, a French Body Corporate, of 62, Boulevard Victor Hugo, 92209 Neuilly-sur-Seine, France, 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:- The present invention relates to a pipe socket assembly particularly suitable for accommodating a male spigot end having a rough outer surface and large manufacturing tolerances such as a stoneware one.

The object of the invention is to provide a cheap and reliable pipe socket assembly of this kind.

According to the invention, there is provided a pipe socket assembly, comprising an internally cylindrical bell made from a polyolefin and having a free end, and an annular sealing element made from an ethylenepropylene-diene-methylene rubber vulcanized with sulphur or a substance providing sulphur, said sealing element comprising a heel portion welded to the end of the bell, a first frustoconical lip which extends from the heel portion inwardly of the bell and has a male end gripping bead at a free end thereof, and a second lip which is radially outside the first lip and extends inwardly of the bell from the end of the first lip adjoining the heel portion and adapted to provide a seal against the inner wall of the bell when a male spigot end is inserted in the bell, the second lip being frustoconical and divergent toward the inner end of the bell and radially entirely spaced from the inner wall of the bell before insertion of said male spigot end in the bell.

Further features and advantages of the invention will be apparent from the ensuing description which is given merely by way of example with reference to the accompanying drawing in which: Fig. 1 is an axial sectional view of a pipe coupling sleeve having two socket assemblies according to the invention; Fig. 2 is a half axial sectional view of a sealing element for this sleeve, and Fig. 3 is a half axial sectional view of a modification of a socket assembly according to the invention.

The sleeve 1 shown in Fig. 1 comprises at each end a socket assembly 2 comprising a generally cylindrical bell 3 and an annular sealing element 4.

The sleeve 1 is moulded in one piece from polypropylene or another polyolefin, for example polyethylene. The end of each bell 3 has an inner frustoconical chamfer 5. The two bells are partitioned off from each other by an inner middle radial flange 6.

The sealing element is moulded and vulcanized in one piece from an ethylenepropylene-diene-methylene rubber with sulphur or a substance providing sulphur such as a mercaptan. This sealing element comprises a heel portion 7 for securing the element and a united pair of lips 8 and 9 extending from this heel portion.

The heel portion 7 has in section a shape of a rectangular trapezoid one right angle of which has been cut off. Consequently, it has two radial faces 10 and 11, a cylindrical inner surface 12 which is chamfered at 13 at the end of the sealing element, and a frustoconical outer surface 14. The surface 14 matches the chamfer 5 of the sleeve 1.

The portion comprising the pair of lips 8 and 9 is connected to a region 15 of the face 10 which is on the radially inner side of the latter and is of small thickness. The lip 8 is relatively long and adapted to grip round a male end 16 which is, for example, of stoneware having a rough surface. The lip 8 extends along a cone which is convergent from the region 15 in the direction away from the heel portion 7 and its length is sufficient to ensure that its minimum diameter is less than the outside diameter of the smallest envisaged male end having regard to the manufactured tolerances. In order to increase the gripping effect, the free end of this lip 8 is in the shape of a bead 17 which has a substantially circular cross-sectional shape and provided internally with a sharp edge 18. The thickness of the lip 8 is everywhere distinctly greater than the thickness or radial dimension of the region 15.

The second lip 9 is very short in comparison and extends from the outer surface of the first lip 8 at a short distance from the region 15. It has a triangular cross-sectional shape and extends along a cone which is divergent in the direction away from the heel portion 7.

The end edge 19 of the lip 9 is located inside the geometric cylinder 20 which passes through the circle of intersection of the faces 10 and 14 of the heel portion and therefore has the inside diameter of the bell 3. The thickness of the region 15 is less than the thickness of the lip 8 at any point of the latter and consequently, of course, less than the thickness of the portion comprising the united pair of lips 8 and 9.

In order to secure a sealing element 4 in a bell 3, the matching frustoconical surfaces 5 and 14 are heated and, when the surface 5 has softened, they are applied against each other. The heating may be carried out, for example, by means of a frustoconical heating ring on the two faces of which the surfaces 5 and 14 are applied. The ring is withdrawn before the surfaces are applied against each other. The purpose of the heating of the rubber is to avoid a sudden cooling of the polypropylene upon this application and the formation of a solid film which would hinder the bond between the two materials.

In the course of these operations, the portion consisting of the pair of lips 8 and 9 must necessarily be inserted inside the bell.

Owing to the aforementioned dimensioning of the edge 19, there is no danger of the lip 9 being pushed back during this insertion.

Note that the sealing element 4 undergoes no deformation when it is placed in position in the bell.

When the male end 16 is inserted in the bell 3 provided with the sealing element 4, it tends to move the sealing element 4 along therewith, but the element 4 is retained by the heel portion 7. The male end 16 radially expands the bead 17 and, as the thinnest part of the sealing element is the region 15, the two lips 8 and 9 together move outwardly, that is to say toward the inner wall or surface of the bell 3. When viewed in section, this movement may be defined as a unitary rotation of the two lips 8 and 9 about the region 15 and the amplitude of this movement is sufficient to ensure that the lip 9 is distinctly applied by its outer surface against the wall of the bell 3, as shown in Fig. 1. The seal in the region of the bell is thus ensured, which would not be the case in the absence of a lip 9 since the welding of the heel portion 7 may be imperfect and provide no seal, or in the absence of the weakening of the sealing element formed by the region 15 since in this case there would be a danger of the relatively long lip 8 bending in its middle part between the bead 17 and the lip 9 without the latter moving toward the inner wall of the bell 3.

Fig. 3 shows the invention applied to a bell 3a which is in one piece with the end of a pipe Ia. The sealing-element 4a differs from the element 4 of Fig. 2 only in that the outer surface l4a of the heel portion 7a is cylindrical and has a diameter equal to the inside diameter of the bell 3a, with an outer end flange 14b. This sealing element is secured to the bell in the following manner: the flange 14b is applied against the end edge of the bell 3a and a cylindrical ring 20 having an inner end flange 21 caps the assembly and is adhered to the outer surface of the bell by a layer of adhesive 22. The flange 14b has previously been welded to the flange 21 and is thus disposed, and may be clamped, between the end edge of the bell 3a and the flange 21. By way of a modification, the ring 20 could be screwed on, or clipped to, the bell 31. The flange 14b could also be welded to the end edge of the bell 3a, in which case the ring 20 would be unnecessary, unless it is employed for affording a protection.

The socket assembly 3204a operates in the same manner as the socket assembly described with reference to Fig. 1, with the same advantages.

Thus in any case where the sealing element is secured to the bell by axially inserting the element in the bell and where the fixing of the heel portion to the bell might not provide a suitable seal in the region of the bell, the invention ensures a perfect seal against the bell without creating a problem when placing the sealing element in position.

WHAT WE CLAIM IS: 1. A pipe socket assembly, comprising an internally cylindrical bell made from a polyolefin and having a free end, and an annular sealing element made from an ethylenepropylene-diene-methylene rubber vulcanized with sulphur or a substance providing sulphur, said sealing element comprising a heel portion welded to the end of the bell, a first frustoconical lip which extends frown the heel portion inwardly of the bell and has a male end gripping bead at a free end thereof, and a second lip which is radially outside the first lip and extends inwardly of the bell from the end of the first lip adjoining the heel portion and adapted to provide a seal against the inner wall of the bell when a male spigot end is inserted in the bell, the second lip being frustoconical and divergent toward the inner end of the bell and radially entirely spaced from the inner wall of the bell before

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the manufactured tolerances. In order to increase the gripping effect, the free end of this lip 8 is in the shape of a bead 17 which has a substantially circular cross-sectional shape and provided internally with a sharp edge 18. The thickness of the lip 8 is everywhere distinctly greater than the thickness or radial dimension of the region 15. The second lip 9 is very short in comparison and extends from the outer surface of the first lip 8 at a short distance from the region 15. It has a triangular cross-sectional shape and extends along a cone which is divergent in the direction away from the heel portion 7. The end edge 19 of the lip 9 is located inside the geometric cylinder 20 which passes through the circle of intersection of the faces 10 and 14 of the heel portion and therefore has the inside diameter of the bell 3. The thickness of the region 15 is less than the thickness of the lip 8 at any point of the latter and consequently, of course, less than the thickness of the portion comprising the united pair of lips 8 and 9. In order to secure a sealing element 4 in a bell 3, the matching frustoconical surfaces 5 and 14 are heated and, when the surface 5 has softened, they are applied against each other. The heating may be carried out, for example, by means of a frustoconical heating ring on the two faces of which the surfaces 5 and 14 are applied. The ring is withdrawn before the surfaces are applied against each other. The purpose of the heating of the rubber is to avoid a sudden cooling of the polypropylene upon this application and the formation of a solid film which would hinder the bond between the two materials. In the course of these operations, the portion consisting of the pair of lips 8 and 9 must necessarily be inserted inside the bell. Owing to the aforementioned dimensioning of the edge 19, there is no danger of the lip 9 being pushed back during this insertion. Note that the sealing element 4 undergoes no deformation when it is placed in position in the bell. When the male end 16 is inserted in the bell 3 provided with the sealing element 4, it tends to move the sealing element 4 along therewith, but the element 4 is retained by the heel portion 7. The male end 16 radially expands the bead 17 and, as the thinnest part of the sealing element is the region 15, the two lips 8 and 9 together move outwardly, that is to say toward the inner wall or surface of the bell 3. When viewed in section, this movement may be defined as a unitary rotation of the two lips 8 and 9 about the region 15 and the amplitude of this movement is sufficient to ensure that the lip 9 is distinctly applied by its outer surface against the wall of the bell 3, as shown in Fig. 1. The seal in the region of the bell is thus ensured, which would not be the case in the absence of a lip 9 since the welding of the heel portion 7 may be imperfect and provide no seal, or in the absence of the weakening of the sealing element formed by the region 15 since in this case there would be a danger of the relatively long lip 8 bending in its middle part between the bead 17 and the lip 9 without the latter moving toward the inner wall of the bell 3. Fig. 3 shows the invention applied to a bell 3a which is in one piece with the end of a pipe Ia. The sealing-element 4a differs from the element 4 of Fig. 2 only in that the outer surface l4a of the heel portion 7a is cylindrical and has a diameter equal to the inside diameter of the bell 3a, with an outer end flange 14b. This sealing element is secured to the bell in the following manner: the flange 14b is applied against the end edge of the bell 3a and a cylindrical ring 20 having an inner end flange 21 caps the assembly and is adhered to the outer surface of the bell by a layer of adhesive 22. The flange 14b has previously been welded to the flange 21 and is thus disposed, and may be clamped, between the end edge of the bell 3a and the flange 21. By way of a modification, the ring 20 could be screwed on, or clipped to, the bell 31. The flange 14b could also be welded to the end edge of the bell 3a, in which case the ring 20 would be unnecessary, unless it is employed for affording a protection. The socket assembly 3204a operates in the same manner as the socket assembly described with reference to Fig. 1, with the same advantages. Thus in any case where the sealing element is secured to the bell by axially inserting the element in the bell and where the fixing of the heel portion to the bell might not provide a suitable seal in the region of the bell, the invention ensures a perfect seal against the bell without creating a problem when placing the sealing element in position. WHAT WE CLAIM IS:

1. A pipe socket assembly, comprising an internally cylindrical bell made from a polyolefin and having a free end, and an annular sealing element made from an ethylenepropylene-diene-methylene rubber vulcanized with sulphur or a substance providing sulphur, said sealing element comprising a heel portion welded to the end of the bell, a first frustoconical lip which extends frown the heel portion inwardly of the bell and has a male end gripping bead at a free end thereof, and a second lip which is radially outside the first lip and extends inwardly of the bell from the end of the first lip adjoining the heel portion and adapted to provide a seal against the inner wall of the bell when a male spigot end is inserted in the bell, the second lip being frustoconical and divergent toward the inner end of the bell and radially entirely spaced from the inner wall of the bell before

insertion of said male spigot end in the bell.

2. A socket assembly as claimed in claim 1, wherein the thickness of the sealing element is reduced in a region between the heel portion and the portion comprising the two lips.

3. A socket assembly as claimed in claim 1 or 2, wherein the heel portion has a radial face welded to the end edge of the bell.

4. A socket assembly as claimed in claim 1 or 2, wherein the end of the bell has an inner chamfer to which a matching frustocopical surface of the heel portion is welded.

5. A socket assembly as claimed in any one of the claims 1 to 4, wherein the radially inner surface of the first lip is smooth.

6. A modification of the socket assembly as claimed in claim 1 or 2, wherein the heel portion is welded to a ring mounted on the bell.

7. A pipe socket assembly, substantially as hereinbefore described with reference to and as shown in Figs. 1 and 2 or Fig. 3 of the accompanying drawing.

8. A pipe coupling sleeve, comprising at each end thereof a pipe socket assembly as claimed in any one of the claims 1 to 6.