GB2048412A - Improvements in or relating to releasable pipe-line or pipe fitting connections - Google Patents

Abstract

A releasable connection for a pipe-line or pipe fitting comprises a pair of connection pieces (1, 2), each arranged to be secured to an end of a pipe or fitting. One connection piece (1) includes a recess or groove (1c) to retain a pcking ring (3) against dislodgement, the packing ring (3) projecting out of the groove (1c) so that it is deformed by the second connection piece (2) as the connection pieces are drawn together when being assembled for use. The deformation of the sealing ring (3), which is of an elastomeric material is guided by the shape of the meeting faces of the connection pieces (1, 2) to enter the residual gap between the connection pieces when fully engaged, the engagement being limited by a shoulder formed within a mating recess of one of the connection pieces. The axially outward surfaces of the engaged connection pieces define a pair of conic sections and a split clamping ring (4), embracing the connection pieces, both draws the pieces together and maintains them in engagement. <IMAGE>

Description

SPECIFICATION Improvements in or relating to releasable pipe-line or pipe fitting connections The present invention relates to pipe fittings for connecting lengths of pipe or for connecting a length of pipe to an appliance. In particular the invention is concerned with fittings having a deformable packing ring and which include two connecting pieces which are locked together, the connecting pieces being respectively secured to the ends of a pipe and to the appliance with which it is to be connected, the connecting pieces enclosing a deformable packing ring and including provision for compressing the connecting pieces together in the direction of the pipe axis.

Connections including such fittings facilitate the installation and dismantling particularly of complex pipe-line layouts and the connection of pipes to appliances and make such installation or dismantling economically viable.

It is known to provide at the ends of pipes or fittings rspectively massive cylindrical flanges, which are connected to each other by suitable means, for example by bolts or studs.

In this case packing material suitable for use consists, for example, of rigid or elastic packing rings having a circular or rectangular cross-section. In order to ensure that, in the process of installation, the packing rings are retained in position, the flanges are provided with grooves in which the packing rings are partially bedded. When such flange connections are used, particularly in conjunction with rectangular cross-section packing rings, the initial stress and working pressure are transferred entirely to the packing rings by the flanges. This stress, acting to distort the rings, greatly reduces their effective life.

Other proposals have avoided this disadvantage by providing flanges which are arranged to touch each other in an initial loading condition in the area lying outside the packing ring.

In this case the packing ring is deformed and occupies a gap which is provided between the flanges within the packing ring boundary. In this construction the packing ring is not subject to dynamic stress when the connection is in use, but such flange connections have other considerable disadvantages. One such disadvantage stems from the fact that because the packing ring is not securely fixed in position during installation and dismantling, it is readily damaged, particularly during installation.

Furthermore, other known pipe connections use standardised screwed structures (e.g. as according to Standard DIN 11851), which also have considerable disadvantages. Although these connections include rings of rectangular cross-section and damage to the packing ring during installation and dismantl- ing is almost impossible, such screw fittings require a relatively large displacement distance during installation and dismantling.

Moreover, the packing ring is dynamically stressed by an operational force, thereby shortening its effective life. The most important disadvantage consists in that the screw structure of the fitting is not formed in such a way as to be bacteriologically unobjectionable during use for the conveyance of products where avoidance of this form of contamination is a primary concern. In the automatic cleaning of parts having difficult access, residue of such products can settle and, particularly in the fields of food and drink industries, the use of this form of pipe connection can thus provide sources of re-infection.

One object of the present invention is the provision of a releasable pipe or pipe-fitting connection of the kind referred to which, while avoiding the disadvantages reviewed above of previously proposed connections, can at the same time be produced more economically in terms of materials and other costs than the known devices.

According to the present invention a releasable connection for pipe or pipe fittings comprising two connection pieces adapted to be secured to the ends of pipes or pipe fittings, the connection pieces surrounding an elastomeric packing ring provided between them and being urged together in the direction of the flow axis of the pipe or pipe fittings is characterised in that the first connection piece and the second connection piece are each provided with a guiding surface and an inner mating surface; in that the first connection piece is provided with a groove in which the packing ring is bedded; and in that the packing ring is distorted by the co-operation of the mating surfaces in the finally assembled position of the connection pieces to swell out into the gap between the first and second connection pieces at least to occupy the gap to the extent of the divergence of the gap within the fitting.

It is the purpose of the invention to provide a releasable connection for pipes or pipe fittings, especially for installations which must comply with the requirements of hygiene, in which the seal cannot be damaged mechanically or chemically. In the case of mechanical damage, it will be realised that this is most likely to be caused during installation by, for example, sharp edges of the connection pieces. In the present case such damage is unlikely even during installation. The invention also provides for a very small gap in a radial direction between the seal and products conveyed by the pipe, and also ensures that, in this gap, the seal is arched towards the interior of the fitting, this configuration depending on the length-width ratio, in which the length is smaller than the width.

In use, due to thermal stresses, conventional connections can "work", and thereby become loose, so that an operator of the plant might feel obliged to "adjust" the connection.

Because of this activity, resulting in further squashing of the seal, the seal can be mechanically damaged or destroyed. In the context of chemical damage, it should be pointed out that, e.g. installations handling foods, in particular, must be continually cleaned. The cleaning material used, in the case of the present invention should have only the smallest possible exposed area of seal as a working surface.

An object is achieved by the present invention, in particular in the case where previously used connection pieces, which were welded on to the pipes to be connected, are omitted and the connection is made without those parts which are connected directly on to the pipes.

For this purpose a first connection piece and a second counter-connection piece use a fixing method whereby the pipes or pipe fittings make a connection using guide surfaces so that axial pressure on the connection causes the connection pieces to prop up and centre each other over the inner construction region, that the first connection piece is provided with a groove in which the packing ring is bedded before assembly of the connection, having regard to the shape and stress applied to the ring, and in that after the assembly of the connection the final position of the connection pieces is limited by the inner installation area, the packing ring is swelled, in consequence of its deformation produced by the second or counter-connection piece, into the gap between the first and second connection pieces and at least occupies that part of the gap at which it diverges out of the groove.

The rigid connection of the connection piece and counter-connection piece over the inner construction region avoids dynamic stressing of the packing ring while the connection is in use. The final stress is confined within the connection excluding the packing ring. The inner construction area is also responsible for the mutual centreing of the connection pieces in their final working positions.

During assembly of the connection, the guide areas provided in the connection pieces allow mutual guiding into position free from rough edges.

By means of its shape and/or the final stress applied bedding the packing ring into the groove within the connection piece, the packing ring is assured of a definite fixed position within the connection pieces. It is thus impossible for the packing ring to fall out and be damaged particularly during installation of the connection. As the counter-connection piece is moved towards its final working position, the elastomeric packing ring is increasingly deformed. Because the material of the ring is incompressible, it swells out, under the pressure of the counter-connection piece, into the gap between the conection and counter-connection pieces whereby in its final working position the remaining groove crosssection is so proportioned that at least that part of the gap diverging towards the groove is filled up by the deformed packing ring.This swelling of the packing ring this groove-diverging part of the gap creates bacteriologically objectionable conditions in that area. Remnants of produce conveyed along the pipe have no access to those back-edges of the gap area which are critical with regard to the cleaning techniques applied. Because, during installation and dismantling, the packing ring is deformed only once on each occasion, it has a longer effective life-span as compared with dynamically stressed packing rings of known constructions. It is also noted that the appearance of fatigue and dissolution do not exist at all or are not apparent after a considerably longer period of use.

In one advantageous form of construction, the groove is provided with a rounded base with a radius smaller than the radius of the undeformed circular cross-section of the packing ring. In addition it is provided that the base of the groove is, on the outside of the groove, led tangentially into a cylindrical outer flange-surface and, on the inside of the groove, is led tengentially into a cylindrical inner flange-surface which is as long as the extended length of the packing ring. In addition, the inner flange-surface is followed by a conical surface having an angle of inclination which effectively reduces the width of the groove at that point.By forming the groove into this special configuration, firstly, the elastomeric packing ring is stretched, whereby a closed position of the packing ring is produced inside the connection piece; secondly, it also permits the ring to bed within the groove so that it is positively prevented from falling out of the groove.

In order to protect the packing ring during installation and dismantling from stress the limit of the undeformed packing ring surface, while the ring is bedded into the groove, is defined by an arc extending from out of the groove and lying within the space available in the connection piece during installation and dismantling.

In a further development of the pipe or pipe-fitting connection the connection piece and counter-connection piece each have an area of conical configuration which co-operate with a similar configuration formed in the cross-section of a clamping arrangement to compress the connection pieces according to a wedging action in the direction of the axis of symmetry of the pipe fitting housing or pipe-line which is to be connected. By means of a known clamping-ring, which provides this clamping action, the material-saving method of the invention is implemented.

Under certain circumstances of use, a cost saving is possible, where in accordance with a further development of the invention the counter-connection piece is formed on a pipefitting housing or a pipe constituting part of a pipe-line by reforming or swaging without the need for boring. The cost saving is possible by the development of a counter-connection piece as an iron part on the one hand and on the other by obviating the need for a separate closing-force coupling piece.

In a further development of the invention, the previously known cylindrical flanges are formed on the connection piece and on the counter-connection piece which are, by means of known connection means, closed together in connection with each other. This development combines the advantages of the present invention with those of the known flange connections, the flanges replacing the clamping ring structure referred to above.

Yet another development has the advantage of the present invention in that conventional pipe-screwing fittings are provided on the connection pieces, by means of which an encircling loose-nut having an internal screw thread is used to draw the connection pieces together in the conventional manner. The disadvantages described earlier in connection with the conventional screwed pipe fitting are avoided by this further development.

A connection arrangement embodying the present invention will now be described, by way of example, with reference to the accompanying drawing, which shows a cross-section through a releasable pipe connection with an elastomeric packing ring and in which the connection pieces are drawn together with a clamp ring.

In the drawing, a first connection piece 1 and a second or counter-connection piece 2 are shown in their final working position. They touch and centre over an inner installation surface Ai. A conical surface-length 1 g on the connection piece 1 and a complementary conical surface-length 2c on the counter-connection piece 2 together form a flange having an external angle. A connector 4, such as a hollow two-piece split clamoin ring, is provided with a cone-shaped recess having an internal angle corresponding to the angle, and, in accordance with a wedging principle, compresses the connection pieces 1, 2 together in the direction of the symmetrical flow axis of the pipe-line or pipe fittings which are to be connected.

The inner installation surface Ai within the connection piece 1 and an outer installation surface Aa are arranged in precisely located positions to position the connection pieces 1, 2 in relation to one another. This precisely located installation position is maintained by the connector 4, leaving a gap T between the connection piece 1 and the connector 4. A radial gap M is required between the connection pieces 1 and 2 to ensure that they cannot become wedged into each other in the final working position. On assembling the connection, the leading surfaces 1 h, 2d on the respective connection pieces 1 and 2 take up their positions without mutual interference.

In the connection piece 1, a groove or cavity 1 c is provided whose base is rounded with a radius R. The continuation of the groove section, from its rounded base extends, on the outside of the groove 1 c, tangentially into a cylindrical flange-surface Id.

The opposite side of the groove section also extends from the groove base, on the inside of the groove 1 c, tangentially into a cylindrical inner flange-surface 1 e. The axial extent of the inner flange-surface 1 e conforms to the intended size of an elastomeric packing ring 3, which is, by its shape and stretch characteristics bedded in the groove 1 c to lie between the connection pieces 1 and 2. The inner flange-surface 1 e of the groove is then continued into an inward-turning conical surface 1f, which, by its angle of inclination reduces the width of the groove 1 c at this point. The cone surface If then extends into a radius r to form, with the opposed counter-connection piece 2, a gap S within the bore of the fitting.

In the final position of the connection pieces 1 and 2, which is determined by their engagement at the inner installation surface Ai, the packing ring 3 is deformed to swell into the gap S, between the connection piece 1 and the counter-connection piece 2, by the action of the counter-connection piece 2. The notional area I in the drawing shows the extent of deformation and the displaced material of the ring is indicated as the area II within the gap S. The cross-sectional dimensions of the groove 1 c are calculated in such a way that at least the part of the gap S diverging into the groove 1 c is filled by the swelling II of the packing ring 3. The radius R of the base of the groove 1 c is smaller than the cross-sectional radius of the packing ring 3 in its undeformed state.This difference in radii is so calculated that the extent by which the ring 3 projects out of the groove 1 c in its undeformed state is such that it is kept within the level of the counter-connection piece 1 as indicated by the outer edge F in the drawing.

The connection piece 1 is shown as connected by a welding seam 1 a to the main supply side of the pipe-line, or to the main supply side of a pipe fitting housing, or appliance, for example. On the other side of the connection, the counter-connection piece 2 is connected by a welding seam 2a, which connects an optional length L2 of the counterconnection piece 2 with the secondary side 2b of the pipeline or the secondary side of a pipe fitting housing or appliance. The freeend of the connection piece 2 may be formed without a boring or turning operation. For example, it may be swaged or otherwise formed to develop the radius R2 on the optional length L2 of a pipe-length or a pipeline fitting.

As shown in the drawing, an axial distance exists between the perpheral edges E and F of the respective connection pieces 1 and 2. This distance E-F, termed the installation or dismantling displacement distance, must be al lowed for both during installation and dismantling of the connection. Because, as noted above, the projection of the undeformed packing ring 3 out of the groove 1 c lies wholly within this displacement distance H, damage to the ring 3 by squashing or shearing during installation ordismantling is always avoided.

It will be understood that the welding seams 1 a and 2a as shown in the drawing, may be replaced by other known and conventional techniques for joining parts of the same or dissimilar materials.

Claims (14)

1. A releasable connection for pipe or pipe fittings comprising two connection pieces adapted to be secured respectively at the ends of pipes or pipe fittings, the connection pieces surrounding an elastomeric packing ring provided between them and being urged together in the direction of the flow axis of the pipes or pipe fittings, characterised in that the first connection piece and the second connection piece are each provided with a guiding surface and an inner mating surface; in that the first connection piece is provided with a groove in which the packing ring is bedded; and in that the packing ring is distorted by the co-operation of the mating surfaces in the finally assembled position of the connection pieces to swell out into the gap between the first and second connection pieces at least to occupy the gap to the extent of the divergence of the gap within the connection.

2. A releasable connection as claimed in Claim 1, further characterised in that the packing ring has a circular cross-section; in that the groove has a base formed with a radius smaller than that of the radius of the cross-section of the ring, the groove formation further being so shaped that the base curvature continues on the outside wall tangentially into a cylindrical outer flange surface and continues on the inside wall tangentially into a cylindrical inner flange surface extending a distance corresponding to the extent of outward displacement of the centre of the ring section when the ring is in position in the groove, and thenceforward continues as a conical surface extending inwards, whereby its angle of inclination reduces the width of the groove.

3. A releasable connrction as claimed in Claim 1 or Claim 2, further characterised in that the extent of an arc formed by the undeformed packing ring surface projecting from the groove when the ring is in position in the groove lies within the installation distance required for installation and dismantling of the connection plates.

4. A releasable connection as claimed in any one of Claims 1 to 3, further characterised in that the first and second connection pieces are each provided with outwardly extending portions shaped to co-operate in use to form a cone-shaped extension which is arranged to co-operate with an internal recess of a clamping member which, in use, applies a compressive force in accordance with a known wedging principle, to bring the connection piecas together, the force acting in the direction of the symmetrical axis of the connection pieces.

5. A releasable connection as claimed in Claim 4, further characterised in that the second connection piece is produced by reshaping an optional length of pipe or pipe-line fitting.

6. A releasable connection for pipes or pipw fittings for use in installations which have stringent requirements, particularly hygienic requirements, including connection pieces adapted to be secured to pipe or pipe fitting ends, a packing ring being included between the connection pieces, the arrangement of the connection pieces being characterised in that a recess is provided in or at a first one of the connection pieces into which the second connection piece is axially moved; in that a shoulder is provided within the recess to limit the extent of relative movement of the connection pieces during installation and in that the packing ring is held in a cavity formed in the first connection piece by its shape and/or stress, the ring extending out of the groove with its outermost surface lying inwardly of the connection piece with respect to its outward face.

7. A releasable connection as claimed in any one of Claims 1 to 6, further characterised in that the second connection piece is developed into a conical form and in that the first connection piece has a complementary conical form.

8. A releasable connection as claimed in Claim 7, further characterised in that the second connection piece is developed into shape by forming an end of a pipe.

9. A releasable connection as claimed in any one of Claims 6 to 8, further characterised in that part of the undeformed packing ring when the ring is in the cavity extends out of the cavity a greater axial distance than that between the cavity and the shoulder.

1 0. A releasable connection as claimed in any one of Claims 6 to 9, further characterised in that the cavity is formed as a groove provided in the forst connection piece.

11. A releasable connection as claimed in any one of Claims 6 to 9 further characterised in that the cavity for the packing ring is formed principally by flange parts on the pipes or pipe fittings which are to be con nected.

12. A releasable connection as claimed in Claim 11, further characterised in that the connection includes a divided clamping device such as a clamp ring to hold the connection pieces together.

13. A releasable connection as claimed in any one of the preceding claims, further characterised in that between the packing ring groove and the bore of the connection pieces when in working position is a narrow gap into which the packing ring is deformed to project towards the interior of the bore within the packing pieces.

14. A releasable connection constructed and arranged substantially as described with reference to the accompanying drawing.