NO803433L - WIRING DEVICES. - Google Patents

Description

The present invention relates to a device for sealingly connecting hollow parts, e.g. pipelines, comprising a spigot part and a socket part.

More specifically, the invention relates to a sealing coupling device which can withstand pressure and temperatures of more than 100 bar and 100°C respectively, without being damaged and without its mechanical properties and sealing ability being weakened, even during tests where the device is exposed to thermal shocks, repeated pressure cycles and accelerated aging.

Fig. 1 shows a schematic section of a common coupling device of the type to which the present invention relates. According to this figure, each of two pipe parts 10, 12 includes a flange 14, 16, and these flanges are mutually sealed by means of a sacrifice 18 which is arranged in a suitable groove in one of the flanges 14, 16. As the seal is formed by the O-ring 18, the fluid transported through a pipeline formed by the pipelines 10 and 12 can penetrate all the way to the O-ring 18 as indicated by the number 20. The pressure fluid, acting on the surfaces of the two flanges 14 and 16, causes separating forces represented by the resultant 22. The separating forces are usually counteracted by holding forces represented by the resultant 24. As the forces 22 and 24 act in opposite directions on each flange,

in each section plane, e.g. black shown in fig. 1, each flange is acted upon by a couple of forces which seek to push the O-ring 18 away from the opposing surface.

British patent document no. 820 1.13 describes a coupling device of the usual type mentioned above, where a sealing ring is arranged very close to the inner surface of the pipe parts with the aim of reducing the resultant 22 by reducing the flat pressure fluid acts on. However, the force that holds the two flanges together acts radially outside the sealing ring, so that when the fluid pressure in the pipeline formed by pipe parts 10 and 12 is high,

the two pressure surfaces tend to separate and the sealing properties are reduced. According to the patent document, the sealing ring is also not enclosed on all sides, so that the internal fluid pressure can push the ring into a radially extending space.

French patent document no. 2 138 250 describes a coupling device in which an O-ring is placed in a groove which is also arranged as far inside as possible, as it is delimited along one of its surfaces by the pin end of a pipe part which is inserted in the groove to the complementary pipe part. The patent thus describes an assembly where the resultant 22 (Fig. 1) is reduced to a value practically equal to zero. However, here too the clamping device for the two coupling parts will act with a force 24 outside the sealing ring, so that the forces exerted by the pressure fluid again tend to weaken the seal in the area of the sealing ring. For the application described in the French patent, this ratio is of little importance as the tubes have a very small diameter and a very large thickness in relation to the diameter, so that the seal does not pose any major problem.

However, the mentioned assemblies are completely useless for pipe parts with a very large diameter. Thus, taking into account the need to keep space, weight and not least costs at a low level, it is not possible to use thicknesses greater than what is strictly necessary to absorb high forces due to fluid pressure. For pipe parts that have a diameter of 50 8 mm and contain fluid with a working pressure of 70 bar, the separating force between the two pipe parts, at a test pressure of 105 bar, will be 2.1 x 10^ N.

Use of techniques according to the above-mentioned patents would necessitate a considerable oversizing of the parts. According to the invention, the problem is not solved by over-dimensioning different elements, but by removing these power pairs from the place where their effect is most harmful.

More specifically, according to the invention, the force couple which seeks to separate the flanges 14,16 from each other (Fig. 1) is removed in the area of the sealing ring 18, by allowing the resultant 4 to act in such a way that its axis intersects the sealing ring.

More specifically, if one considers all the forces acting in the space, the coupling device according to the invention is such that the location of the points of attack of the resultant of the forces exerted by a clamping device is located on a circle whose diameter is substantially equal to the mean diameter of the slot that occupies the sealing ring.

More specifically, the invention relates to a coupling device for the sealing connection of two hollow cylindrical parts, of the type that comprises

- a sleeve element which delimits a cylindrical cavity, the bottom of which forms a first pressure surface substantially perpendicular to the axis of the cavity, - a tap element which has a second pressure surface and is arranged to be inserted into the sleeve element, - at least one sealing ring arranged in a circular groove which is designed in one of the surfaces and arranged to lie tightly against the other pressure surface when the pin element and the sleeve element are in engagement with each other, and - a clamping ring arranged to retain the pin element in the cavity of the sleeve element, when forces are applied that press the pin element and the pressure surface of the sleeve element. According to the invention, when the spigot and socket element are held in relation to each other by means of the clamping ring, - the two pressure surfaces lie directly against each other and surround the sealing ring on all sides in the groove, and - the location of the attack points of the resultant of the forces which due to the clamping ring acts on the pin element in each axial plane located on a circle whose diameter is substantially equal to the mean diameter of the groove.

The mean diameter of the pressure surface which does not include the groove is also preferably approximately equal to the mean diameter of the groove.

According to one embodiment, the sleeve element has protrusions that project into the cavity, and the clamping ring has protrusions arranged to cooperate with the sleeve element's protrusions, which protrusions are evenly distributed along the inner circumference of the sleeve element and along the outer circumference of the clamping ring, so that they enable a bayonet connection. The cooperating surfaces on the protrusions of the sleeve element and the clamping ring can, for example, form helical inclined planes. Furthermore, the protrusions of the sleeve element and the clamping ring preferably have different lengths so that one of the protrusions extends past the other when they are in engagement position.

Moreover, the screw surfaces of the inclined planes, seen in longitudinal section, can be inclined in relation to a plane across the sleeve element's axis in such a way that when the sleeve element and the clamping ring interact, the sleeve element's projection presses against the axis of the cavity.

According to another embodiment, the clamping ring is screwed in

the sleeve element.

It is also advantageous that the surface of the clamping ring which interacts with the pin element and the surface of the pin element which interacts with the clamping ring is made up of two conical surfaces with the same apex angle so that clamping the coupling device causes the pin element and the socket element to be centered in relation to each other.

According to another embodiment of Ise's form, the pressure surfaces of the pin element and the sleeve element can be conical with the same top angle, so that the pin and sleeve elements are aligned automatically when the coupling device is clamped together.

It is also advantageous to have a device which prevents rotation of the clamping ring in relation to the sleeve element when the ring is tensioned.

According to an advantageous feature of the invention, the clamping ring is made up of several parts so that it can be placed on a pipe after the elements of the coupling device have been welded to the two pipes.

Other features and advantages of the invention will be apparent from the following description in connection with the drawings, of which fig. 1 has been previously discussed, and where: Fig. 2 is a perspective view of an embodiment of the coupling device according to the invention in the assembled state shown with a removed part, Fig. 3 is a side view of the clamping ring of the coupling device in fig. 2, and Fig. 4 is a longitudinal section of another embodiment of the coupling device according to the invention.

The coupling device shown in fig. 2 and 3, generally indicated by the number 2 8, is designed for connecting two pipe parts 30, 32. It comprises a socket element 34, a tap element 36 and a clamping ring 38. The socket part 34, which is welded in advance in a workshop to the pipe part 30 which indicated by the number 39, comprises a cylindrical part .40 in extension of the pipe part 30, a flange-shaped part 42 which forms an internal pressure surface 44 in which a circular groove 46 is extended and an outer cylindrical part 48.

The outer part or collar 48 has protrusions 50 which face inwards. The 50 surfaces of the springs that face the pressure surface

44 form helical inclined planes.

The spigot element 36 comprises a cylindrical part 52 in extension of the pipe part 32 to which it is welded as indicated by the number 53. The spigot element further comprises a protruding flange 54 which forms a pressure surface 56 for abutment against the pressure surface 44 of the socket element.

The clamping ring 98 has a cylindrical main part 58 with a radially projecting projection 60 and notch 62 in the axially outward facing surface.

The coupling device further comprises a sealing ring 64 which is arranged in the groove 46 in the sleeve element 34.

According to the invention, the two pressure surfaces 44 and 56 on the sleeve and tap elements 34 and 36, respectively, are in contact with each other and enclose the sealing ring 64 on all sides. Furthermore, in each longitudinal section plane, the point of attack 66 for the resultant 68 of the forces which the ring 38 exerts against the flange 54 is at the same distance from the longitudinal axis 70 of the coupling device as the center of the track 46. Accordingly, the axis 72 of the force resultant 68 component parallel to the axis 70 will pass through the center of the track 46.

Fig. 2 is not drawn to scale. Thus, the collar 48 of the sleeve element is shown as located at a large distance from the outer part of the flange 54 so that the engagement between the sleeve element's and the clamping ring's protrusions, respectively 50 and 60, should appear more clearly. The correct proportions appear from fig. 3 which only shows the clamping ring with protrusions 60 which form helical inclined planes 74 arranged to cooperate with the protrusions 50 helical inclined planes.

More specifically, it appears from fig. 2 that the cooperating surfaces 76 on the protrusions 50 of the sleeve element and the protrusions 60 of the ring rather in relation to a plane across the axis 70, in the direction downwards towards this axis, in the representation in fig. 2, i.e. when the clamping ring is tightened, the forces have a component parallel to the axis 70 of the coupling device, but also with a radial component. This radial component is directed inwards on the protrusions 50 and outwards on the protrusions 60. When the clamping ring is thus tightened, the protrusions 50 will be drawn closer to the axis 70 and prevent spreading of the collar 48 to the sleeve element which, as it is exposed to compressive forces, has a greater mechanical nic strength. In addition, the clamping ring centers automatically in relation to the sleeve element's projection.

It should also be noted that on the embodiment according to fig. 2, the cooperating surfaces on the tap element flange 54 and the clamping ring 38 form conical surfaces, so that when the ring 38 is clamped against the sleeve element 34, the tap element 36 will have a tendency to self-center in the sleeve element.

When the coupling device is to be used, the socket element 34 is welded to the pipe part 30 and the spigot element 36 is welded to the pipe part 32 at the workshop, after the clamping ring 38 has been placed on the pipe part 32. When the pipe parts are to be connected together on site, the spigot element is introduced into the socket element and the clamping ring is shifted so that its projections 60 are brought in line with the spaces between the socket element's projections 50. By then turning the ring 38 in the correct direction, the projections 50 and 60 are brought into mutual engagement and the pin element is clamped against the socket element, so that the sealing ring is clamped. The coupling can be locked by drilling a hole 77 in the collar 48 and one of the protrusions 60 and by inserting a pin, or by striking the protruding end of one of the protrusions with a hammer.

Fig. 4 shows another embodiment of the invention where the clamping ring interacts with the sleeve element by means of a screw connection. More specifically, the coupling device 78 according to the invention is intended to connect two pipe parts 80, 82. The sleeve element 84 which is welded to the pipe part 80 exhibits a pressure surface 90 which extends perpendicular to the longitudinal axis of the device 78 and in which is designed with a groove 92 which occupies a

sealing ring 94. The outer part or collar 96 of the sleeve element 84 is designed with internal threads 98.

The tap element 86 has a pressure surface 100 adapted to cooperate with the surface 90 of the sleeve element.

The clamping ring 88 has external threads 102, complementary to the socket element's internal threads 98. The threads are preferably of the type used on artillery parts and are capable of absorbing extremely high loads parallel to the axis of the coupling device. The ring has protrusions 104 which protrude from the outer radial surface and which are intended for

to enable attraction of the ring 88.

When using the coupling device according to the invention, the sleeve element 84 is welded to the pipe part 80 at the workshop, and the tap element 86 is welded to the pipe part 82, after the ring 88 has been placed on this pipe part. When the parts 80 and 82 are placed in place, the pin element is inserted into the sleeve element and the ring 88 is attracted into the sleeve element, so that it presses the pin element against the sleeve element. After tightening, the ring 88 can be locked to the collar 96 by local deformation of the threads with the help of a tool that is inserted into a hole 103 which is drilled transversely through the collar 96.

It will be clear that many variants of the coupling device according to the invention are possible. In the embodiment according to fig. 2 and 3, the number of protrusions in the sleeve element and the clamping ring can thus vary. In the embodiment according to fig. 4, the external threads 102 or the internal threads 98 can either be continuous or interrupted.

In the embodiment according to fig. 2 and 3, it is suggested that the cooperating surfaces of the clamping ring and the pin element are conical surfaces, and that the cooperating surfaces of the clamping ring and the sleeve element have helically inclined surfaces which act to center the pin element in the sleeve element. For the embodiment according to fig. 4, no self-centering device is described there. However, the different embodiments can include such a self-centering device, either as described in connection with fig. 2, or of another type. E.g. can the actual pressure surfaces of the pin element and the sleeve element be designed slightly conical and complementary, so that these surfaces themselves ensure the centering.

Although it is stated that the sealing ring is occupied in the sleeve element, the groove can of course instead be formed in the pin element.

The clamping ring 38 or 88 is shown as made in one piece. This is not a necessary move. It is thus particularly appropriate to use a clamping ring consisting of at least two parts for mounting the ring on a pipe part which carries a coupling device, after the pin or socket element has been welded to said pipe part. It is only necessary that the clamping ring, after its various parts have been brought into place, appropriately exerts the necessary force on the tap element. According to the embodiment shown in fig. 2, the clamping ring can e.g. simply be diametrically divided into two parts, possibly with hinge or centering devices that ensure appropriate setting of the two parts of the clamping ring. According to the embodiment shown in fig. 4, the ring can also be diametrically slotted, and centering devices, e.g. of V shape, enables appropriate setting of the two half rings. In this last embodiment, it can be advantageous that the threads of the ring are interrupted near the cooperating surfaces of the ring's various parts.

The pin element and/or the socket element can be provided with an electrical coating, whereby an insulated connection is formed.

The coupling device according to the invention can possibly be dismantled without significant damage that could prevent it from being used again.

The invention is particularly suitable for transport under pressure through pipelines with a large diameter, of fluids such as hydrocarbons and natural gas, and solid substances such as minerals and carbon, as the pipelines can then have an internal wear-resistant coating.

Claims (12)

1. Coupling device for the sealing connection of two hollow cylindrical parts, of the type that comprises - a sleeve element which delimits a cylindrical cavity whose bottom forms a first pressure surface substantially perpendicular to the axis of the cavity, - a pin element which has another pressure surface and is arranged to is introduced into the sleeve element, - at least one sealing ring arranged in a circular groove that is formed in one of the surfaces and arranged to lie tightly against the other pressure surface when the spigot element and the sleeve element are in engagement with each other, and a clamping ring designed to retain the pin element in the socket element's cavity, by applying forces that press the pin element and the pressure surface of the socket element, characterized in that when the pin and socket element are held in relation to each other by means of the clamping ring, - the two pressure surfaces lie directly against each other and enclose on all sides the sealing ring in the groove, and - the location of the points of attack of the resultant of the forces which, due to the clamping ring, act on the pin element in each axial plane are located on a circle whose diameter is substantially equal to the mean diameter of the groove. 2. Device according to claim .1, characterized in that the mean diameter of the pressure surface which does not include a groove is approximately equal to the mean diameter of the groove. 3. Device according to claims 1 and 2, characterized in that the sleeve element has protrusions that extend into the cavity and that the clamping ring has protrusions for engagement with the sleeve element's protrusions, which protrusions are regularly arranged around the inner circumference of the sleeve element and the outer circumference of the clamping ring to form a bayonet connection. 4.. Device according to claim 3, characterized in that the interacting surfaces on the protrusions of the sleeve element and the clamping ring are in the form of screw surfaces. 5. Device according to claim 4, characterized in that the protrusions on the sleeve element and the protrusions on the clamping ring have different lengths, so that protrusions on the sleeve element or on the clamping ring extend beyond a protrusion on the clamping ring or the sleeve element, respectively, when the sleeve element and the clamping ring are together 1 to s.t score. 6. Device according to claim 5, characterized in that the screw surfaces, seen in longitudinal section, are inclined in relation to a plane across the sleeve element's axis, the inclined position being such that when the sleeve element and the clamping ring are engaged, the socket element's projection is pressed against the axis of the cavity. Device according to claims 1 and 2, charac- see t that the clamping ring is screwed into the sleeve element. 8. Device according to one of the preceding claims, characterized in that the surface of the clamping ring that interacts with the pin element and the surface of the pin element that interacts with the clamping ring are both conical with the same top angle so that clamping the coupling device causes the pin element and the socket element to be centered in relation to each other . 9. Device according to one of the preceding claims 1-7, characterized in that the pressure surfaces of the pin element and the sleeve element are conical with the same top angle so that the pin and sleeve elements are self-centering during clamping of the coupling device. 10. Device according to one of the preceding claims, characterized in that it comprises a device to prevent rotation of the clamping ring in relation to the sleeve element when the ring and the element are clamped in relation to each other. 11. Device according to one of the preceding claims, characterized in that the clamping ring consists of several parts so that they can be placed in place on a pipe after the elements of the coupling device have been welded to the two ends of the pipe. 12. Pipe part, characterized by the fact that it the smallest at one of its ends carries a pin element or a socket element of a coupling device according to one of the preceding claims.