GB2031543A - Pipe couplings - Google Patents

Abstract

A coupling between a female pipe part 1 of polyethylene and a male metal pipe part 11 comprises a sliding ring 4 connected with the outer side of the male pipe part 11 and forming together with the female part 1, an annular space 18 accommodating tensile stress resistance providing means, consisting of a split ring 21 situated in a recess 20 of the male pipe part 11 and a clamping ring 22, 23 at each side of the split ring 21. Small distances between the walls of the recess 18 and the two clamping rings 22, 23 allow a limited movement of the male pipe part 1 with the clamping rings 22, 23 and the split ring 21, with respect to the female part 1. <IMAGE>

Description

SPECIFICATION Transitional pipe part The invention relates to a transitional pipe part, at least comprising a female pipe part and a male pipe part, an annular sealing member in between the female pipe part and the male pipe part, and tensile stress resistance providing means.

Atransitional pipe part of this type is known. Said known transitional pipe part comprises a polyethylene female pipe part and a metal male pipe part, which metal pipe part is coated with a polyethylene coating. So as to obtain a tensile stress resistant connection, the plastic female pipe part comprises a threaded metal nut, which is screwed upon a threaded portion of the male pipe part, whether or not coated with a polyethylene coating.

The pipe part coated with a polyethylene coating is further connected with a closing valve, which serves for closing off or for supplying gas from a main circuit to polyethylene gas-supplying lines in a building. In order to effect said connection the transitional pipe part comprises a second socketshaped part wherein the gas supply line is received, for instance by welding.

Although a similar transitional pipe part provides a tensile stress resistant connection between the female pipe part and the metal male pipe part, it is inefficient in so far as the male pipe part and the female pipe part will be unable to be displaced with respect to one another at the occurrence of pressure impacts, attended by notable tensile forces, resulting in an undesired relaxation of and creeping tendencies in the materials being used. Said phenomena might lead to an undesired hampering of the impact strength properties of plastics.

The present invention aims to provide a pipe transition part of the abovementioned type, which overcomes the above disadvantages and which alleviates any undesired relaxation or occurrence of creeping properties in plastic parts as used, especially with respect to impacts occurring after having mounted the respective components.

This object is attained in accordance with the invention in that the tensile stress resistance providing means in the pipe transitional parts allow a relative movement of the female and the male pipe part with respect to one another. Advantageously the tensile stress resistance providing means will substantially not deform the male pipe part towards a radial direction.

Owing to these features, an impact in a pipe line, attended by a tensile force, can be easily absorbed without the polyethylene parts of the female pipe part being subjected to notable tensile forces, whilst the male pipe part can return unhampered towards its original position after the disappearance of said impact.

The tensile stress resistance providing means are advantageously located in a chamber positioned at the front side of the female pipe part, said chamber being formed by means of a sliding ring connected with the female pipe part. Said connection of the sliding ring with the female pipe part may be effected by a screw or an adhesive connection, or, advantageously by a welded connection, provided a sliding ring is used which can be welded to the female pipe part.

Said sliding ring therefore appropriately consists of polyethylene when the female pipe part also consists of polyethylene.

A good seal is obtained by the presence of an annular sealing member in between the female pipe part and the male pipe part. Said annular sealing member mostly has the shape of an O-ring, an additional annular sealing member in the form of an O-ring being present between the sliding ring and the male pipe part.

Due to the formation of a chamber for receiving the tensile stress resistance providing means, said chamber being located at the front side before the female pipe part, the transitional pipe part in accordance with the invention can be easily formed, so that mounting same is considerably facilitated and the relative expenditures are considerably reduced.

Actually, the tensile stress resistance providing means can be firstly mounted upon the female pipe part, whereafter the chamber for receiving said tensile stress resistance providing means, can be formed by means of the sliding ring.

In this respect is should be noted that it is known to receive tensile stress resistance providing means in an annular chamber of a male pipe part. In the latter case however, the wall opposite said chamber is always provided with a bore, for the introduction of a plastics bar material, which fills up the entire chamber. From this is follows that a relative movement of the male pipe part and the female pipe part with respect to one another, is impossible, while moreover providing a wall of said chamberwith a bore, will be particularly inappropriate, as will be described hereinafter.

The opening for introducing a bar material into the chamber for the receipt of tensile stress resistance providing means, is apt to facilitate the entrance of dirt, dust and the like, which will disadvantageously influence the tensile stress resistance providing means, e.g. will damage or pallute them.

In a transitional pipe part in accordance with the present invention, however, the above problems will be entirely overcome.

The tensile stress resistance providing means advantageously comprise a longitudinally subdivided ring, said ring cooperating at least clampingly with the male pipe part and being located at least at distance from one end of the chamber.

The use of a longitudinally split ring, clampingly cooperating with the male pipe part promotes obtaining a very good tensile stress resistant connection.

In a particular advantageous embodiment of the present invention, a closed retaining ring is provided preferably at either side of the subdivided (split) ring, said closed retaining ring or rings coperating with the outside of the male pipe part, whereby at least one retaining ring is located at distance from the extreme ends of the chamer, thus enabling a relative movement of the male pipe part with respect to the female pipe part.

The retaining ring or the retaining rings is or are appropriately provided with a chamfer, cooperating with the longitudinally subdivided ring.

Said construction offers the advantage that a very small recess at the outside of the female pipe part, will suffice for the receipt of the longitudinally subdivided clamping ring, thus causing the wall of the male pipe part to be only slightly or not at all influenced.

The expression chamfered is also to be understood as being an eventual processing of the extreme end of the retaining ring, situated opposite the longitudinally subdivided clamping ring, up to a cross-sectional circular-section-shaped surface.

The plastic female pipe part of the transitional plastic pipe part in accordance with the invention, may be connected with a gas supply circuit in the building, which gas suply circuit may then for example, consist of polyethylene pipes. For that airm the polyethylene gas supplying pipe of the building may be welded together with the inside of the female pipe part of the transitional pipe part. Should the male pipe part consist of metal, said metal pipe may be coated with a plastic coating, in particular with a polyethylene coating.

In that case, the polyethylene coating upon the male pipe part extends to beyond the point where the male pipe part cooperates with the tensile stress resistance providing means.

The invention will now be clarified by way of example only, with respect to an embodiment in the drawing, diagrammatically showing a transitional pipe part in accordance with the invention.

In the drawing, a transitional pipe part 1 is shown, comprising a polyethylene female pipe part 1. Said female pipe part is provided with an annular groove 2, wherein a sealing ring 3 is received.

Said female pipe part 1 is connected with a polyethylene sliding ring 4, by a joint 5, upon the outside 6 of the female pipe part 1. An other solution for effecting said joint by means of an adhesive or a screw may of course also be provided.

The sliding ring 4, comprises a sleeve 7, which extends upon the outside of the female pipe part 1, said sliding ring 4 also comprising a front part 8, having a diameter, smaller than the sleeve 7 of the sliding ring 4.

In the front part 8 of the sliding ring, an annular grooves 9 is provided, in which an O-ring 10 is disposed.

The transitional pipe part in accordance with the invention further comprises a metal male pipe part 11, being provided with a first polyethlene coating 12, and a subsequent thicker polyethylene coating 13. The first polyethylene coating 12 cooperates with the sealing ring 10. The extreme end 14 of the metal pipe 11 can be welded to e.g. a gas main closing valve, after completion of which, said entirety can be brought onto the market.

A similar assembly can for instance be easily connected with a gas-supplying line 15, consisting of e.g. polyethylene, which is welded upon the female pipe part 1, by means of a joint 16.

An annular chamber 18 is formed at the front side before the end 17 of the female pipe part 1 by means of the sliding ring 4, in order to obtain a good tensile stress resistant connection between the metal male pipe part 11, which pipe part mostly consists of copper. Said chamber 18 therefore comprises on the one hand the front end of the female pipe part and on the other hand the inwardly directed wall 19 of the sliding ring 4.

A circular groove 20 is formed within the metal pipe 14, in order to impair the properties ofthe metal male pipe part 11 as little as possible. The annular groove 20 comprises a longitudinally split clamping ring 21, which in this case likewise consists of metal.

From the foregoing it will be obvious that the longitudinally split clamping ring 21 could be replaced by a closed ring which could be secured or clamped upon the male pipe part 11 by using an adhering means or e.g. by a welding operation.

So as to obtain a tensile stress resistance which is as optimum as possible, two closed clamping rings 22 and 23 are clampingly secured at either side of the female pipe part 1. The lower sides 22a and 23a of said clamping rings 22 and 23 cooperate with a clamping ring 21, subdivided towards a longitudinal direction.

Said ends 22a and 23a are chamfered in order to obtain a cooperation which is as effective as possible, but it goes without saying that the parts 22a and 23a need not necessarily be chamfered, but can also be provided with a cross-sectional circular sectionshaped surface.

Due to the fact that the sides 24 and 25 of the clamping rings are located at distance from the front wall 17 of the male pipe part 11 and the inwardly directed transistional wall 19 of sliding ring 4, said male pipe part 11 will be able to move with respect to the female pipe part 1, at the occurrence of an impact. Said rings 22 and 23 will be able to return to their original position after removal of said impact.

It has been found that owing to the abovedescribed features, less relaxation and creeping symptoms will occur both in the plasics material of the sliding ring and of the female pipe part and in other plastics pipelines connected therewith.

The mounting of a transitional pipe part in accordance with the invention is moreover, very easily to be effected which will notably decrease the relative expenditures.

The mounting is effected as follows: A sliding ring 4 is slid upon the outside of the male pipe part 11. The groove 9 of said sliding ring 4 comprises a sealing ring 10. Subsequently a closed metal ring 22 is slid clampingly upon the outside of the male pipe part 11, while after having applied a longitudinally subdivided ring 21 cooperating clampingly with groove 9, a second metal ring 23 is applied, which closed metal ring 23 likewise cooperates clampingly with the male pipe part 11.

The sliding ring 4 is then slid forward until the inwardly directed transitional wall 19 of the sliding ring 4 is located at distance from the metal ring 22.

The male pipe part 11 is subsequently slid into the female pipe part 1 until the side wall of the second metal clamping ring 23 is located at a small distance from the front wall 17 of the female pipe part 1.

Thereafter the sliding ring 4 is welded upon the female pipe part 1.

A transitional pipe part is thus obtained which is able to appropriately withstand any impacts and tensile forces.

Should tensile forces actually occur, the male pipe part 11 and the female pipe part 1 are able to move with respect to one another, thus causing the side wall 24 to adjoin the front wall 17 or the side wall 23 to adjoin the inwardly directed transitional wall 19 of the sliding ring 4. The ring 22 or 23 will return to its original position after removal of said impact.

It has been found that relaxation and creeping symptoms in polyethylene used for gas-supplyingcircuits in homes or buildings and in a female pipe part, will be notably reduced.

As can be seen in the drawing, the tensile stress resistance providing means do not cooperate with the clamping means exerting a radial pressure.

In the transitional pipe part of the invention relative movements of the pipe parts have no effects on the seal as the seal is situated between the pipe end and the tensile stress resistance providing means.

Claims (10)

1. A transitional pipe part, at least consisting of a female pipe part and of a male pipe part, an annular sealing member, disposed in between the female pipe part and the male pipe part, and tensile stress resistance providing means, wherein the tensile stress resistance providing means in the transitional pipe part allows a relative movement of the female and the male pipe part with respect to one another.

2. A transitional pipe part as claimed in claim 1, wherein the tensile stress resistance providing means will substantially not deform the male pipe part radially.

3. A transitional pipe part as claimed in claims or 2, wherein the tensile stress resistance providing means is accommodated in a chamber situated at the front end before the female pipe part, said chamber being formed by means of a sliding ring connected with the female pipe part, preferably an annular sealing member being present in between the sliding ring and the male pipe part.

4. A transitional pipe part as claimed in claims 1 to 3, wherein the tensile stress resistance providing means comprises a longitudinally split ring, which longitudinally split ring is located at distance from at least one end of the aforementioned chamber, whilst preferably the longitudinally split ring at least clampingly cooperates with the male pipe part.

5. A transitional pipe part as claimed in any or more of the preceding claims, wherein the tensle stress resistance providing means consisting of a longitudinally split ring, being accommodated in an annular recess of the male pipe part and a closed retaining ring is preferably located at either side of the longitudinally split ring, cooperating with the outside of the male pipe part.

6. A transitional pipe part as claimed n claim 5, wherein the retaining ring or rings cooperates or cooperate with the longitudinally split ring, at least one retaining ring being located at distance from the ends of said chamber, whilst preferably the retaining ring or rings have a chamfered surface, cooperating with the longitudinally split ring.

7. Atransitional pipe part as claimed in any or more of the preceding claims, wherein the male pipe part consists of polyethlene or wherein the male pipe part consists of metal.

8. A transitional pipe part as claimed in any or more of the preceding claims, wherein the male pipe part consists of a metal pipe, coated with a plastics coating preferably a polyethylene coating.

9. A transitional pipe part as claimed in any or more of the preceding claims, wherein the longitudinally split ring cooperates with a pipe part consist ing of metal, the part of the metal pipe cooperating with the annular sealing member, being provided with a plastic coating and the further part of the male pipe part preferably being coated with a thicker plastic coating.

10. A transitional pipe part as claimed in claims 1 to 9, wherein the plastic sliding ring is connected with the female pipe part by welding and/or the transititional pipe part is welded together with a polyethlene pipe and/or the metal pipe is provided with a closing valve.