Sealed Joint Assembly

Field of the Invention

This invention relates to a sealed joint assembly and also a seal element for use in a sealed joint assembly. Additionally, the invention relates to a sealed connection between two flanged pipe ends.

Background Art

It is common to use pipelines to provide conduits for fluid mass and heat transfer applications, a typical example of which is pipework for conveying steam. Typically, such pipelines comprise sections of pipe connected one to another.

In high pressure applications, it is necessary to provide an effective sealed joint between the pipe sections. In applications relating to fluid transfer at high pressures, one way of establishing a sealed joint is to have end flanges on the pipe sections, with each flange having an end face in which there is an annular recess. The annular recesses of the two adjacent pipe sections co-operate to receive a seal ring intended to establish a fluid seal at the joint. The seal ring has angular faces adapted to sealingly locate against corresponding angular faces within the recesses. When the flanged ends are fastened together, the seal ring is clamped within the two annular recesses. This provides an effective seal when the joint is under full pressure, although leakage can occur when the pipeline is not under full pressure.

It is against this background, and the problems and difficulties associated therewith, that the present invention has been developed.

Disclosure of the Invention

According to a first aspect of the invention there is provided a seal element comprising two ring portions disposed in side by side relation with a gap therebetween, and a coupling portion interconnecting the two ring portions to

establish a fluid seal across the gap, the coupling portion being adapted to yieldingly resist movement of the two ring portions together to reduce or close the gap.

Preferably, the two ring portions comprise rigid rings.

Preferably, each rigid ring defines an axially inner face confronting the gap and an axially outer face, the axially outer face defining a sealing face.

Preferably, the coupling portion comprises two end sections each attached to a respective one of the rings and an intermediate section configured as a spring for elastic deformation to provide the yielding resistance to movement of the two ring together to reduce or close the gap.

Preferably, the two end sections are attached to radially inner sides of the rings.

Preferably, the intermediate section is configured as a loop formation protruding into a region between the two rings. Preferably, the axially inner section of each ring is configured to, in combination with the other ring, define a space for receiving the intermediate section of the coupling portion.

The sections of the two rings defining the space may provide a seat against which the loop formation can locate upon elastic deformation of the intermediate section.

Typically, the coupling portion is formed of Stainless Steel, such as 321 Stainless Steel, although it can be formed of any other suitable material including other 300 series Stainless Steels, Inconel, Incoloy, Hastalloy, Nickel, and Monel to suit the fluid medium inside of the system.

Typically, each ring is formed of carbon steel, 4140, a 300 series Stainless Steel, or 253 MA, although any other suitable material may of course be used.

According to a second aspect of the invention there is provided a seal assembly between two flanged portions each having an end face, the seal assembly comprising an annular recess in each end face and a seal element comprising two seal ring portions one sealingly accommodated in each of the two annular recesses, the seal element further comprising a coupling portion interconnecting the two ring portions to establish a fluid seal across a gap between the two ring portions, the coupling portion being adapted to yieldingly resist movement of the ring portions together to reduce or close the gap.

According to a third aspect of the invention there is provided a connection between two pipe sections providing a sealed joint therebetween, the connection comprising a flanged end on each pipe, each flanged end defining an end face and an annular recess in the end face, two seal rings one sealingly accommodated in each of the two annular recesses, a coupling portion interconnecting the two rings to establish a fluid seal across a gap between the two rings, the coupling portion being adapted to yieldingly resist movement of the rings together to reduce or close the gap.

Preferably, an intermediate sealing element is provided between a seal face defined by each recess and the corresponding end face on the respective ring. The intermediate sealing element may comprise a strip of compressible sealant material.

According to a fourth aspect of the invention there is provided a pipeline comprising two pipe sections interconnected by a connection according to the third aspect of the invention.

Brief Description of the Drawings

The invention will be better understood by reference to the following description of one specific embodiment thereof as shown in the accompanying drawings in which:

- A -

Figure 1 is a fragmentary cross-sectional view of a sealed joint according to the embodiment, with the joint assembly being shown in a condition prior to bolting of pipe end flanges together;

Figure 2 is a view similar to Figure 1 , with the exception that the pipe end flanges are shown bolted together and the joint is in a condition prior to pressurisation;

Figure 3 is a view similar to Figure 2, with the exception that the joint is shown in a pressurised condition;

Figure 4 is a sectional perspective view of a seal element forming part of the sealed joint according to the embodiment;

Figure 5 is a sectional perspective view of a ring portion forming part of the seal element;

Figure 6 is a sectional perspective view of a coupling portion forming part of the seal element;

Figure 7 is a schematic cross-sectional view of the seal element shown in a free length condition (being the condition which it would occupy when the joint is as shown in Figure 1);

Figure 8 is a schematic cross-sectional view of the seal element in a preset condition under maximum compression but prior to pressurisation (being the condition which it would occupy when the joint is as shown in

Figure 2);

Figure 9 is a schematic cross-sectional view of the seal element in the pre-set and pressurised condition under maximum compression (being the condition which it would occupy when the joint is as shown in Figure 3);

Figure 10 is a schematic cross-sectional view of the seal element in an exploded condition;

Figure 11 is a cross-sectional view of a flange set forming part of the joint according to the embodiment;

Figure 12 is a cross-sectional view of one of the flanges of the flange set shown in Figure 11 ; and

Figure 13 is a cross-sectional view of the other flange in the flange set of Figure 11.

Best Mode(s) for Carrying Out the Invention

The embodiment shown in the drawings is directed to a joint 10 for establishing a high pressure sealed connection between two pipe sections (not shown). The joint 10 is appropriate for use in pipelines operating with internal fluid pressures in the order of 7MPa.

The joint 10 comprises a flange set 11 and a seal element 13 within the flange set 11.

The flange set 11 comprises two flanges 14, 15 each adapted to be fitted on adjacent ends of pipe sections intended to be connected together to form a pipeline. Each flange 14, 15 comprises an inner portion 17 adapted to be secured to the respective pipe section and a flange section 19 incorporating a plurality of holes 21 for receiving bolts 23 to provide a bolted connection between the flanges 14, 15. Each flange 14, 15 has an end face 25 incorporating an annular recess 27. The two annular recesses 27 co-operate to define an annular cavity 29, as best seen in Figure 11 of the drawings. The annular cavity 29 receives the seal element 13, as will be explained in more detail later.

The flange set 11 as previously described incorporating the annular cavity 29 is of conventional construction and is known in the prior art. In prior art

applications, a sealing ring is accommodated in the annular cavity 29. For this purpose, each recess 27 has an inner end face 31 and an angular side face 33 adjacent the inner end face 31. In the prior art, the angular face 33 provides a sealing face which co-operates with the prior art sealing ring in an endeavour to establish a sealed joint between the two flanges.

The prior art flange set is used in the present embodiment in order that the joint according to the invention can be retro-fitted to existing pipe installations. It should, however, be understood that other flange sets, including flange sets constructed particularly for use with the invention, can be utilised if desired.

In the joint 10 according to the present embodiment, the end faces 31 of the recess 27 are used for sealing purposes, and not the angular sealing faces 33, as will become apparent later.

The seal element 13 comprises two ring portions 41, 42 and a coupling portion 43 extending between the two ring portions. Each ring portion 41 , 42 comprises a rigid ring 45 having a radially outer face 47, a radially inner face 49, an axially outer side face 51 and an axially inner side face 53. A chamfered face 55 extends between the radially outer face 47 and the axially outer side face 51 , as shown in the drawings. The chamfered face 55 provides clearance for the angular sealing face 33 within the recess 27 when the ring portion is received therein, as will become apparent later.

The axially inner side face 53 is configured to provide a protruding straight section 57, a recessed straight section 58 and a curved section 59 extending therebetween. The protruding straight section 57 is adjacent the radially outer face 47 and the recessed straight section 58 is adjacently radially inner face 49, as best seen in Figure 10. .

The two ring portions 41 , 42 are disposed in axial alignment one adjacent another, with the axially inner side faces 53 confronting each other. The coupling portion 43 maintains the two ring portions 41 , 42 in such a relationship. With this

arrangement, the confronting axially inner side faces 53 define a gap 61 between the protruding straight sections 57, and also define a recess 63 between the recessed straight sections 58 and the curved sections 59, as best seen in Figures 7 to 10.

The coupling portion 43 comprises two end sections 71 , 72 and an intermediate section 73 therebetween.

Each end section 71 , 72 is attached to one of the ring portions 41 , 42, and the intermediate portion 73 received within the recess 63. More particularly, end section 71 locates against and is secured to the radially inner face ^' 49 of ring portion 41 , and end section 72 locates against and is secured to the radially inner face 49 of ring portion 42. In the arrangement shown, each end section 71 , 72 is attached to the respective ring portion by welding, such as for example by fillet weld 75.

The coupling portion 43 supports the two ring portions 41 , 42 in a spaced apart relationship to establish the gap 61 therebetween, as shown in Figure 7. Further, the coupling portion 43 is adapted to yieldingly resist reduction or closure of the gap 61. In this regard, the intermediate portion 73 functions as a spring which undergoes compression upon reduction of the gap 61 , as shown in Figures 8 and 9. In Figure 9, the gap 61 has been closed entirely in the sense that inner side faces 53 are in abutment at the straight sections 57 thereof .

The intermediate portion 73 is configured as a loop 74 which protrudes into the recess 63, such configuration in conjunction with elastic properties of the material from which the coupling portion is made, providing a spring for elastic deformation to provide the yielding resistance to movement of the two rings portions 41 , 42 together to reduce or close the gap 61.

When the spring provided by the coupling portion 43 is in its free length condition (that is, when the spring is not under compression to establish a resistive spring

force), the two ring portions 41 , 42 are spaced apart with the gap 61 at the maximum width. As the two ring portions 41 , 42 are moved together to reduce the gap 61 , the coupling portion 43 generates a spring force which resists such movement and thereby urges the two ring portions 41 , 42 away from each other to expand the gap 61.

As the coupling portion 43 undergoes compression, the distortion of the loop 74 is accommodated within the recess 63.

When the flanged joint 10 is fully loaded and under pressure, the gap 61 is either reduced or closed t. In the arrangement shown in Figure 9, the gap 61 is closed and the loop 74 deforms to seat against the recessed straight sections 58 and the curved sections 59. There may, however, be circumstances where the end faces 25 are not in abutment when the flanged joint 10 is fully loaded. In such circumstances, the final gap 61 would be of a size calculated to handle the internal pressure within the interconnected pipe sections. The presence of a final gap may be advantageous in that it would offer some tolerance for installation of the coupling in the field.

When the seal element 13 is installed within the cavity 29 within the flange set 13, as best seen in Figures 1 , 2 and 3, the outer axial face 51 of each ring portion 41 , 42 confronts the inner face 31 of the respective recess 27. A fluid seal between the confronting faces 31 , 51 is established by an intermediate seal element which in the arrangement shown comprises a compressible seal strip 81 formed of any appropriate material. In this embodiment, the sealing strip 81 comprises gasket material, such as, for example, graphite sealing gasket material or fibre-reinforced sealing gasket material.

The seal element 13 is dimensioned so that it can be accommodated within the cavity 29 with the spring established by the coupling portion 43 in its free length condition prior to bolting of the flanges 14, 15 together, as shown in Figure 1. The dimension of the sealing element 13, as well as the gap 61 between the two seal ring portions 41 , 42, is calculated so that the two ring portions are urged

together to close the gap 61 when the flange set 11 is in the pre-set condition, at which the flange faces 25 are in abutting relationship, as shown in Figure 2. In this condition, the inner faces 31 of the recesses 27 engage against the end faces 51 of the ring portions 41 , 42, establishing a fluid seal therebetween by virtue of the intervening sealing strip 81. At this stage, the spring force generated by the compressed spring formed by the coupling portion 43 urges the ring portions 41 , 42 away from each other to maintain sealing contact between the faces 51 , 31. In this condition, the seal element 13 establishes a fluid seal between the flanges of the flange set 11. As the pipeline is pressurised, fluid pressure acts on the interior boundary of the intermediate portion 73. In certain applications, the fluid pressure may be such that it urges the intermediate portion to seat against the ring portions 41 , 42 as illustrated in Figure 9 of the drawings. In this way, the intermediate portion 73 is supported by the two abutting ring portions 41 , 42 against the influence of the fluid pressure. The coupling portion 43 establishes a seal between the two abutting ring portions 41 , 42, preventing escape of fluid between the protruding straight sections 57 which are abutting each other. With this arrangement, the effectiveness of the seal within the joint 10 increases with increasing pressure within the pipeline.

From the foregoing, it is evidence that the present embodiment provides a simple yet highly effective joint between pipe sections which can sustain high pressure. A particular advantage of the joint is that it can be retro-fitted to existing pipelines which have flange sets of the type described and illustrated in Figures 11 , 12 and 13.

It should be appreciated that the scope of the present invention is not limited to the scope of the embodiment described above. In particular, modifications and improvements can be incorporated without departing from the scope of the invention.

Throughout the specification and claims, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.