BACKGROUND

a. Field of the Invention

The present invention relates to a connector, an assembly including two pipe sections and a connector and to a method of connecting two pipe sections. In particular, the present invention relates to a flange connector for use on a riser used in offshore oil exploration and production, a riser assembly and to a method of connecting two pipe sections in a riser.

b. Related Art

Risers consist of sections of pipe that need to be secured together to form a contiguous pipe (or an effectively continuous pipe). Accordingly, the securement between the different pipe sections needs to be strong and reliable. The sections of pipe are often provided with flanges to enable the pipe section to be easily secured together. Each flange may include securement apertures radially spaced around the flanges. Corresponding securing nuts and bolts may then be used to secure the flanges together. Each pair of nut and bolt requires the nuts to be rotated multiple times in order to tighten the securement and provide an effective connection between the two sections of pipe. However, since each connection includes several pairs of nuts and bolts and each requires several or numerous rotations to effect the tightening, the time taken to effectively join the pipes can be relatively long. This is known as bolt torquing. An alternative method comprises bolt tensioning which involves initially stretching a threaded bar or stud and then winding down the nut (which can be done by hand). However, this method is slow due to all the equipment that is needed to stretch the stud. Since the riser cannot be used whilst the sections are being connected, this can be an expensive operation. In addition, the apparatus involved is on large scale such that it may require two workers to handle each nut and/or bolt. For example, the tightening tool for the bolts/nuts may require two divers who will also be working at depth. This has numerous health and safety implications.

Alternative connectors may comprise bayonet type connectors in which a large locking ring which has a greater diameter than the pipe has to be rotated to form the connection. As the locking ring is an integral part of the riser it cannot be easily inspected or maintained, particularly on the inside surface, nor can it be easily replaced.

It is an aim of the present invention to overcome at least one problem associated with the prior art whether referred to herein or otherwise.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a connector for connecting a first conduit section to a second conduit section comprising a first mounting means including a plurality of first securement members provided on the first conduit section and a second mounting means including a plurality of second securement members provided on the second conduit section, the first securement members being engagable with a respective second securement member wherein a first securement member is secured to a respective second securement member by a partial relative revolution.

The first mounting means may comprise a flange and may comprise a flange which is welded, threaded, shrink fitted, clamped or otherwise secured to the first conduit section. The first conduit section may comprise a section of pipeline. The first conduit section may comprise a section of a riser.

The second mounting means may comprise a flange and preferably comprises a flange which is welded to the second conduit section. The second conduit section may comprise a section of pipeline. The second conduit section may comprise a section of a riser.

The connector may comprise a plurality of locking elements to lock the first securement member relative to the conduit in order to prevent relative rotation.

Preferably the connector comprises a locking element to lock the first securement member in either a first locked position or a second unlocked position. Preferably the connector comprises a locking element associated with each first securement member.

Preferably the or each locking element is secured to the first mounting means.

Preferably the or each locking element retains the associated first securement member to the first mounting means.

Preferably the or each first securement member comprises a shaft with a series of radial grooves. Preferably the securement member shaft comprises at least one longitudinal portion without the grooves extending along a part of the length of the grooved section. Preferably the securement member shaft comprises a plurality of ungrooved sections which are radially spaced around the shaft of the first securement member. Each shaft may comprise four sections with radial grooves and four ungrooved sections.

Alternatively, the or each first securement member comprises a shaft with a flared section, and preferably the securement member shaft comprises a plurality of unflared sections which are radially spaced around the shaft of the first securement member.

The first securement member may comprise a bolt. The bolt may comprise a head including engagement means to engage with a tool to enable the bolt to be - A -

rotated.

Preferably the or each second securement member comprises a radially grooved internal surface. Preferably the radially grooved internal surface comprises at least one longitudinal ungrooved portion extending along a part of the length of the grooved section. Preferably the radially grooved internal surface comprises a plurality of ungrooved sections which are radially spaced around a circumference of the radially grooved internal surface of the second securement member.

Alternatively, the or each second securement member comprises a tapered internal surface, and preferably the tapered internal surface comprises a plurality of untapered sections which are radially spaced around a circumference of the tapered internal surface of the second securement member.

The second securement member may comprise an insert or nut.

The partial relative revolution may comprise an angular displacement of less than 180 ^Q and more preferably less than 90 ^Q . The partial relative revolution may comprise an angular displacement of substantially 45 ^Q .

The partial relative revolution may comprise an angular displacement of greater than 15 ^Q and more preferably greater than 30 ^Q .

The partial relative revolution may comprise an angular displacement substantially in the region of 30 ^Q to 60 ^Q .

The first securement member may comprise a rotation limiter to limit the extent of relative rotation between the first securement member and the first mounting means.

The first mounting means may comprise retaining means to retain peripheral equipment to the riser. The second mounting means may comprise retaining means to retain peripheral equipment to the riser.

The connector may comprise retaining means to retain peripheral equipment to the riser.

The connector may comprise retaining means to retain the or each second securement member to the second mounting means.

The connector may comprise sealing means to provide a seal between the first conduit section and the second conduit section. The sealing means may comprise a sealing cartridge.

The connector may comprise alignment means to initially correctly align the first mounting means with the second mounting means. The alignment means may comprise an alignment pin and the alignment means may comprise an alignment aperture provide on one or both mounting means.

According to a second aspect of the present invention, there is provided a kit for a connector for connecting a first conduit section to a second conduit section comprising a first mounting means including a plurality of first securement members provided on the first conduit section and a second mounting means including a plurality of second securement members provided on the second conduit section, the first securement members being engagable with a respective second securement member wherein a first securement member is secured to a respective second securement member by a partial relative revolution.

According to a third aspect of the present invention, there is provided a method of connecting a first conduit section to a second conduit section comprising axially moving a first mounting means towards a second mounting means and partially rotating a plurality of first securement members retained to the first mounting means relative to respective second securement members retained to the second mounting means.

Preferably the method comprises locking the first securement member in a first aligned position.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described, by way of example only, and with reference to the accompanying drawings, in which:

Figure 1 is an exploded perspective view of a preferred embodiment of a connector;

Figure 2 is a perspective view of a preferred embodiment of a connector in an initial unconnected configuration;

Figure 3 is a perspective view of a preferred embodiment of a connector in an aligned but unlocked configuration with the locking elements engaged;

Figure 4 is a perspective view of a preferred embodiment of a connector in an aligned but unlocked configuration with the locking elements disengaged;

Figure 5 is a perspective view of a preferred embodiment of a connector in a locked configuration with the locking elements disengaged;

Figure 6 a perspective view of a preferred embodiment of a connector in a final locked configuration with the locking elements engaged;

Figure 7 is a side view of a preferred embodiment of a connector; Figure 8 is a partial cross-section through A-A as shown in Figure 7;

Figure 9 is a partial cross-section through B-B as shown in Figure 7;

Figure 10 is a detailed cross-section of area C shown in Figure 9;

Figure 1 1 is a perspective view of a part of a preferred embodiment of a connector with the grooves of a first securement member disengaged with the grooves of a respective second securement member;

Figure 12 is a perspective view of a part of a preferred embodiment of a connector with the grooves of a first securement member engaged with the grooves of a respective second securement member;

Figure 13 is a plan view of a second embodiment of the present invention;

Figure 14 is a perspective view of a second embodiment of a connector in an initial unconnected configuration;

Figure 15 is a perspective view of a securement member of the connector shown in Figure 14;

Figure 16 is a perspective view of the securement member of Figure 15 shown in a disengaged position;

Figure 17 is an exploded perspective view of the securement member of Figure 15;

Figure 18 is plan view of one securement member in a connector;

Figure 19 cross-section through A-A as shown in Figure 18; and Figure 20 is a cross-section through B-B as shown in Figure 19.

DETAILED DESCRIPTION

A typical application of the connector described may be for a marine drilling riser used for offshore oil and gas exploration and development. Such risers are typically conduits formed from pipe sections with a 21 inch outer diameter. Such risers are typically used in water depths of 100ft to 10,000ft or greater. The riser can be deployed from a floating vessel or, in shallow water, from a vessel that is stationary and supported by the seabed. The marine drilling riser is used as a conduit for drilling mud to be returned to the surface. Peripheral lines around the outside of the conduit are used for well access and control fluids.

As shown in Figure 1 , a connector for a riser a first mounting means in the form of a first (upper) flange 12 and a second mounting means in the form of a second (lower) flange 14. The first flange 12 is connected to a first section of a conduit and specifically to a riser (not shown) by any suitable means and, for example, may be connected by a welded connection, shrink-fit connection or through a threaded connection. Similarly, the second flange 14 is connected to a second section of a conduit and specifically to a pipeline by any suitable means and, for example, may be connected by a welded connection, shrink-fit connection or through a threaded connection.

The first flange 12 and the second flange 14 include retaining apertures 16 which retain any peripheral lines that may be required. The connector also comprises sealing means in the form of a sealing cartridge 18 which retains the sealing mechanism for the riser and ensures and promotes a good effective seal between the first section of pipeline and the second section of pipeline. The connector further comprises sealing means retainers 20 which retain and secure the sealing cartridge 18 to the first flange 12. The first flange 12 and the second flange 14 comprise at least one alignment aperture 24 to register with at least one alignment member 22 to provide the correct alignment and position of the first flange 12 relative to the second flange 14. The alignment member 22 comprises a location pin which is arranged to locate in the alignment apertures 24 provided in both the first flange 12 and the second flange 14. In use, the alignment member 22 and the alignment apertures

24 enable the first flange 12 to be initially engaged with the second flange 14 in an axial movement and the two flanges 12, 14 do not have to be rotated for this initial engagement.

The connector 10 comprises a plurality of first securement members 26 and a plurality of second securement members 28 in order to secure the first flange 12 to the second flange 14. In the preferred embodiment of the invention, the connector comprises four first securement members 26 and four second securement members 28. The pairs of first and second securement members 26, 28 are radially spaced around the first and second flanges 12, 14.

The second securement members comprise inserts 28 which have an interior radially grooved surface to engage a part of the first securement members 26. In particular, the interior surface is cut with a series of grooves which are spaced along the axis of the insert 28. This grooved surface is then cutaway in a number of equally radially spaced locations. In particular, the grooved surface is cutaway or removed to provide ungrooved sections which extend along the longitudinal extent of the grooved section. In the preferred embodiment, the interior surface is provided with four ungrooved sections which are equally radially spaced around the interior surface. Accordingly, around the interior circumference of the insert 28 the interior is grooved for 45 ^Q , ungrooved for 45 ^Q , grooved for 45 ^Q etc. The interior circumference thereby has four 45 ^Q ungrooved sections and four 45 ^Q grooved sections.

The first securement members 26 comprise bolts 26 which have an exterior radially grooved surface to engage a part of the second securement members 28. In particular, the exterior surface is cut with a series of grooves which are spaced along the axis of the bolt 26. This grooved surface is then cutaway in a number of equally radially spaced locations. In particular, the grooved surface is cutaway or removed to provide ungrooved sections which extend along the longitudinal extent of the grooved section. In the preferred embodiment, the exterior surface is provided with four ungrooved sections which are equally radially spaced around the exterior surface. Accordingly, around the exterior circumference of the bolt 26 the exterior is grooved for 45 ^Q , ungrooved for 45 ^Q , grooved for 45 ^Q etc. The exterior circumference thereby has four 45 ^Q ungrooved sections and four 45 ^Q grooved sections.

In use, the grooved sections of the bolt 26 are aligned with the ungrooved sections of the insert 28. In this position, the ungrooved sections of the bolt are thereby aligned with the grooved sections of the insert 28. This enables the bolt 26 to fully move in an axial movement into position relative to the insert 28 in which the first flange 12 abuts and connects with the second flange 14. Once in this position the bolt can then be rotated through approximately 45 ^Q in order for the grooved sections to register and engage. The spacing of the grooves is set to enable this partial rotation to fully secure the bolt 26 to the insert 28. Since the grooves are radially arranged rather than helically arranged, there is no significant torquing effect when rotating the bolts 26. The rotation of the bolts 28 is limited in order to ensure that the radial grooves on the bolt 26 fully engage with the radial grooves on the screw insert 28.

Each insert 28 includes a respective retaining element 30 which retain the inserts 28 to the second flange 14. The retaining element 30 comprises a screw which secures the insert 28 to the second flange 14 and prevents the insert 28 from becoming inadvertently separated from the second flange 14 prior to or during installation.

Each bolt 26 includes a locking element 32 to retain the bolt 26 to the first flange 12 and also to lock the bolt 26 in either an engaged position or a disengaged position relative to the insert 28. The locking element 32 includes a body 34, two anchor pins 36 and a locking member in the form of a locking pin 38. Once the bolt is located in the respective securement aperture 40 in the first flange 12, the locking element is mounted to the first flange 12 using the anchor pins to retain the bolt 26 in the securement aperture 40. The head 42 of the bolt 26 includes a recessed portion 44 into which a portion of the body 34 extends. The recessed portion 44 comprises an angularly extending section which thereby limits the amount of rotation of the head of the bolt 26. In particular, the head 42 of the bolt 26 may be restrained to move within an arc of rotation of approximately 45 ^Q .

The head 42 of the bolt 26, and more particularly, the recessed portion 44 of the head 42 includes two locking apertures 46 into which the locking pin 38 can be retained. The first locking aperture enables the head 42 of the bolt 26 to be locked whilst the bolt 26 is in a disengaged position. In this position, the bolt 26 is in the correct alignment to be inserted into the insert 28 such that the grooved and ungrooved sections of the bolt 26 and the insert 28 correspond to enable relative axial movement. Once in the fully inserted position, the locking pin 38 can be retracted out of the first locking aperture and the head 42 of the bolt 26 need only be rotated through approximately 45 ^Q in order for the bolt 26 to be secured with the insert 28. In this configuration, the locking pin 38 can then be extended to locate into the second locking aperture in order to lock the bolt 26. This prevents any further rotation of the head 42 of the bolt 26 relative to the insert 28 and thereby locks the first flange 12 to the second flange 14. This securement is repeated for each of the four pairs of bolts 26 and inserts 28 and overall provides a strong connection between the first flange 12 and the second flange 14.

Since each large bolt 26 only needs to be rotated through 45 ^Q , the securement operation is quick when compared to prior art methods. In addition, all of the apparatus is easily retained together both prior and during installation.

The securement sequence is illustrated in Figure 2 to Figure 6. In Figure 2, the bolts 26 are in an aligned position and the locking elements 32 retain the bolts 26 in this position. The two flanges 12, 14 are brought into alignment with each other and this is aided by the use of the alignment member 22 and alignment aperture 24. The two flanges 12, 14 are then brought together through relative axial movement.

Figure 3 shows the two flanges 12, 14 in an unlocked position wherein the shafts of the bolts 26 are located within the inserts 28 but the respective grooved sections are not engaged. At this stage, the locking elements 32 still keep the bolts 26 locked against rotation. The locking pins 38 of the locking elements 32 are then retracted from the respective first locking apertures, as shown in Figure 4. The bolts 26 are then rotated through 45 ^Q in order for the grooved sections of the bolts 26 and the inserts 28 to fully engage, as shown in Figure 5. Finally, once in this configuration, the locking pins 38 are extended into the second locking apertures in order to lock the bolts 26 against relative rotation and to thereby lock the first flange 12 to the second flange 14.

Figure 7 shows a side view of the assembly including a first flange 12 and a second flange 14 connected together in an unlocked configuration. Similarly, Figure 8, Figure 9 and Figure 10 each show more detailed views of parts of the assembly in this configuration. Finally, Figure 1 1 and Figure 12 show comparable views of a bolt 26 and a insert 28 with the grooves disengaged (Figure 1 1 ) and with the grooves engaged (Figure 12).

In another preferred embodiment, the connector 10 comprises five pairs of bolts 26 and inserts 28 radially spaced around the flanges 12, 14. In this embodiment, the radial grooves extend around substantially 45 ^Q of the respective circumference of the shaft of the bolt 26 or the interior of the insert 28. The present invention covers any suitable number of pairs of bolts 26 and inserts 28 spaced around the flanges 12, 14. The number of pairs of bolts 26 and inserts 28 may effect the distribution of the load transmitted through each combination. For example, the load transmitted through each pair will decrease as the total number of pairs increases. Figure 13 shows another preferred embodiment in which the connector 10 comprises six bolts 26 radially spaced around the flange 12.

Figures 14 to 20 show another preferred embodiment of the present invention. Identical features have been given the same reference numerals as in the first embodiment, similar features have been given reference numerals incremented by 100.

A connector 1 10 is shown in Figure 14 having a first mounting means in the form of a first (upper) flange 12 and a second mounting means in the form of a second (lower) flange 14.

The connector 1 10 comprises six first securement members 126 and six second securement members 128. The pairs of first and second securement members 126, 128 are radially spaced around the first and second flanges 12, 14.

As shown in Figure 17, a first securement member 126 comprises a shaft 50 having a proximal section 52 with a constant diameter and a distal section 54, further from the head 42 of the first securement member 126. The distal section 54 has an exterior flared surface 56 such that the diameter of a distal end 58 of the first securement member 126 is larger than the diameter of the distal section 54 of the proximate the proximal section 52 of the shaft 50.

The flared surface 56 is cutaway in a number of equally radially spaced locations. In particular, the flared surface 56 is cutaway or removed to provide unflared sections 60 which extend along the longitudinal extent of the distal section 54. In a preferred embodiment, the flared surface 56 is provided with four unflared sections 60 which are equally radially spaced around the surface 56. Accordingly, around the exterior circumference of the shaft 50 the surface is flared for 45 ^Q , unflared for 45 ^Q , flared for 45 ^Q etc. The exterior circumference thereby has four 45 ^Q unflared sections and four 45 ^Q flared sections.

A second securement member 128 comprises an insert which has a tapered interior surface 62 to engage the flared distal section 54 of the first securement member 126. In particular, the interior surface is tapered such that the internal diameter of the second securement member 128 is smaller at a first end 64 than a second end 66. This tapered surface is then cutaway in a number of equally radially spaced locations. In particular, the tapered surface is cutaway or removed to provide untapered sections 68 which extend along the longitudinal extent of the second securement member 128. In the preferred embodiment, the interior surface 62 is provided with four untapered sections 68 which are equally radially spaced around the interior surface. Accordingly, around the interior circumference of the second securement member 128 the interior is tapered for 45 ^Q , untapered for 45 ^Q , tapered for 45 ^Q etc. The interior circumference thereby has four 45 ^Q untapered sections 68 and four 45 ^Q tapered sections 62.

In use, the flared sections of the first securement means 126 are aligned with the untapered sections of the second securement member 128. In this position, the unflared sections of the first securement member 126 are thereby aligned with the tapered sections of the second securement member 128, as shown in Figure 15. The first securement member 126 is then inserted into the first end 64 of the second securement member 128 and is able to fully move in an axial movement into a position relative to the second securement member 128 such that the first flange 12 abuts and connects with the second flange 14. Once in this position the first securement member 126 can be rotated through approximately 45 ^Q in order for the flared sections 56 to register and engage with the tapered sections 62 of the second securement member 128, as shown in Figure 16. The rotation of the first securement member 126 is limited by the recessed portion 44 of the head 42 of the first securement member 126 in order to ensure that the flared sections on the first securement member 126 fully engage with the tapered sections in the second securement member 128. In this engaged position, the unflared 60 and untapered 68 sections are also aligned creating a longitudinal gap 70 in these regions, seen most clearly in Figure 20.

The angle of the flared and tapered surfaces to the axes of the first 126 and second 128 securement members respectively are complementary so that the surfaces come into touching contact over substantially the whole area when the securement members 126,128 are engaged, shown most clearly in Figure 19. In the engaged position, the flared and tapering surfaces are such that the first securement member 126 cannot be pulled out of the second securement member 128, thereby securing the flanges 12,14 in contact with each other.