GB2526295A

GB2526295A - Subsea clamp connector and pipeline joint

Info

Publication number: GB2526295A
Application number: GB1408887.6A
Authority: GB
Inventors: Nicholas Long
Original assignee: Freudenberg Oil and Gas Technologies Ltd
Current assignee: Freudenberg Oil and Gas Technologies Ltd
Priority date: 2014-05-19
Filing date: 2014-05-19
Publication date: 2015-11-25
Anticipated expiration: 2034-05-19
Also published as: GB201408887D0; GB2526295B

Abstract

Metal trunnions 10, 14 in a clamp connector comprising a chain of pivotally interconnected segments 21-23 which fit over and around a pair of flanged subsea pipeline hubs (fig. 6; 30, 31). The clamp pulls them together with a sealring (fig. 6; 32) positioned between them, when a leadscrew (fig. 3; 2) passing through the bores of the trunnions 10, 14 is rotated. The trunnions 10, 14 are provided with thread seals 50, 55 which act dynamically to retain lubricating oil in both trunnions while the leadscrew is rotated e.g. by a ROV to close or open the clamp. As shown each trunnion includes elastomeric thread seals 50, 55 held in recesses 52, 57 by "L" cross-section metal retaining rings 51, 56 attached to the trunnion so as to prevent relative rotation. Ports 58 allow oil to be injected.

Description

Subsea clamp connector and pipeline joint A known subsea clamp connector comprises; a leadscrew including a first threaded section having a first external thread and a second threaded section having a second external thread, said first and second external threads being threaded on opposite hands; a first generally cylindrical trunnion having a first bore extending substantially radially therethrough, said first bore being provided with a first internal thread such that said first trunnion is adapted to be screwed onto said first threaded section; a second generally cylindrical trunnion having a second bore extending substantially radially tberethrough, said second bore being provided with a second internal thread such that said second trunnion is adapted to be screwed onto said second threaded section; a chain of pivotally interconnected clamping segments including a first chain end segment and second chain end segments; said first and second chain end segments each being provided with an aperture therein adapted to substantially house and allow rotation therein of a corresponding said trunnion.

Subsea clamp connectors of the type described above are well known and are sold under the Registered Trademark OPTIMA.

In use, when the leadscrew is rotated in a first direction to close said clamp, said first and second trunnions and thus said first and second chain end segments are pulled towards each other. Said chain of pivotally interconnected clamping segments are adapted to fit over and around flanges on a pair of subsea pipeline hubs and pull said hubs into sealing interengagement with each other (via the intermediary of a sealring) so as to form a subsea pipeline joint in well-known manner. In that the hubs and sealring need to be matched to each other and to the subsea clamp connector, these components are normally sold together as a kit to form a pipeline joint.

The sealring may be the type sold under the Registered Trademark DUOSEAL.

For a proper seal to be made the joint must be tightened to the correct degree so that the sealring functions with the correct contact pressures. In that the ROV is normally only able to determine the torque applied to the leadscrew but not the tension within the leadscrew, there is a need to provide a consistent and preferably linear relationship between torque and tension in the leadscrew. With this objective in mind and to reduce frictional losses, it is known to provide the leadscrew of a clamp connector of the type described above with dry film lubricant coatings on its threaded sections. These coating work well for a time but deteriorate in use over long periods particularly if the subsea clamp connector is repeatedly opened and closed resulting in significant frictional losses and incorrect tightening of the pipeline joint.

The object of the present invention is to provide a subsea clamp connector of the type described above and a subsea pipeline joint incorporating the same, in which there is a more consistent and preferably linear relationship between torque and tension in the leadscrew. This is effectively achieved by providing thread seals in recesses in both ends of both of said first and second apertures so that lubricating oil can be retained in both trunnions while each trunnion moves along its corresponding section of the leadscrew, when the leadscrew is rotated to close or open the clamp. This eliminates the need to provide dry film lubricant coatings on the external threads of said leadscrew.

It is known to employ elastomeric seals to provide seals between static threaded shafts of fasteners used in fluid systems and bulkheads through which those fasteners pass. Parker Hannifin Corporation makes seals of this type. As previously proposed, each of these thread seals is axially compressed by a nut screwed onto its threaded shaft and provides a static seal. The nuts however lock the thread seals against rotation relative to their shafts, and are not suitable for use in a dynamic sealing situation. The present invention employs dynamic thread seals which provide a seal with a rotating shaft passing therethrough and are attached to their respective trunnions so as to prevent relative rotation therebetween. They do not need to be compressed to provide a seal.

According to a first aspect the present invention a subsea clamp connector comprises; a leadscrew including a first threaded section having a first external thread and a second threaded section having a second external thread, said first and second external threads being threaded on opposite hands; a first generally cylindrical trunnion having a first bore extending substantially radially tberetbrough, said first bore being provided with a first internal thread such that said first trunnion is adapted to be screwed onto said first threaded section; a second generally cylindrical trunnion having a second bore extending substantially radially therethrough, said second bore being provided with a second internal thread such that said second trunnion is adapted to be screwed onto said second threaded section; a chain of pivotally interconnected clamping segments including a first chain end segment and second chain end segments; said first chain end segment being provided with an aperture therein adapted to substantially house and allow rotation therein of said first trunnion; and said second chain end segment each provided with an aperture therein adapted to substantially house and allow rotation therein of said second trunnion; said first bore being provided at a first end thereof with a first annular recess and at a second end thereof with a second annular recess; first and second annular elastomeric thread seals each adapted to screw onto said first external thread and to be at least partially received respectively in said first and second annular recesses; first and second annular metallic retaining rings each secured to said first trunnion so as to prevent relative rotation therebetween, said first annular metallic retaining ring being adapted to pass over said first external thread while retaining said first annular elastomeric thread seal in said first annular recess and said second annular metallic retaining ring being adapted to pass over said first external thread while retaining said second annular elastomeric thread seal in said second annular recess; said second bore being provided at a first end thereof with a third annular recess and at a second end thereof with a fourth annular recess; third and fourth annular elastomeric thread seals each adapted to screw onto said second external thread and to be at least partially received respectively in said third and fourth annular recesses; third and fourth annular metallic retaining rings each secured to said second trunnion so as to prevent relative rotation therebetween, said third annular metallic retaining ring being adapted to pass over said second external thread while retaining said third annular elastomeric thread seal in said third annular recess and said fourth annular metallic retaining ring being adapted to pass over said second external thread while retaining said fourth annular elastomeric thread seal in said fourth annular recess.

Preferably said leadscrew has a splined end and is driven by a drive spindle of a ROV drive bucket assembly, said drive spindle including a splined socket which fits over said splined end.

According to a second aspect subsea pipeline joint comprises a subsea clamp connector according to said first aspect) a pair of subsea pipeline hubs and a sea Iring.

Preferably said pipeline hubs are mating male and female hubs.

More preferably said sealring forms a dual seal.

A preferred embodiment will now be described by way of example only with reference to the accompanying drawings in which:-Figure 1 is a plan view of a subsea clamp connector; Figure 2 is a cross-sectional view through the connector taken along the line A-A in Figure 1; Figure 3 is a side view of a leadscrew 2 shown in Figure 2; Figure 4 is an inverted sear side view of the connector shown in Figure 1; Figure 5 is a cross-sectional view taken along the line B-B in Figure 4; Figure 6 is a cross-sectional view taken along the line E-E in Figure 1; Figure 7 is a perspective view of one a trunnion 10 or 11 shown in Figure 2; Figure 8 is a plan view of that trunnion; Figure 9 is a cross-sectional view through that trunnion taken along the line D-D in Figure 8; Figure 10 is a side view of that trunnion; Figure 11 is a front end view of that trunnion; Figure 12 is a rear end view of that trunnion; and Figure 13 is a plan cross-sectional view taken along the line C-C in Figure 11.

A preferred embodiment will now be described with reference to the drawings referring initially to Figures 1 to 6.

As best shown in Figures 2 and 3, a subsea clamp connector 1 comprises a leadscrew 2 including a first section 3 having a first external thread 4 and a second section 5 having a second external thread 6. Said first and second external threads are threaded on opposite hands.

As best shown in Figures 5, a first generally cylindrical trunnion 10 has a first bore 11 extending substantially radially theretbrough. Said first bore is provided with a first internal thread 12 such that said first trunnion is adapted to be screwed onto said first section 5. A second generally cylindrical trunnion 14 has a second bore 15 extending substantially radially therethrough, said second bore being provided with a second internal thread 16 such that said second trunnion is adapted to be screwed onto said second section 5.

As best shown in Figures 2 and 5, first 2land second 23 chain end segments are pivotally interconnected together (either directly or more conventionally via at least one intermediate segment 22) so as to form a chain 20 of segments. The chain of segments is adapted (to fit round and) to pull together a pair of subsea pipeline hubs 30, 31 into sealing interengagement via the intermediary of a sealring 32 (when said leadscrew is rotated in a first direction). The first chain end segment 21 is provided with a first aperture 45 therein adapted to substantially house and allow rotation therein of said first trunnion 10. Said second chain end segment 23 is provided with a second aperture 46 therein adapted to substantially house and allow rotation therein of said second trunnion.

The leadscrew as shown in Figure 3 is conventional in that it includes a conventional hex drive end 7, a cylindrical bearing end S and between said first 3 and second 5 sections a hex section 9 by means of which the leadscrew can be rotated using a spanner. As shown in Figure 5 a hex drive shaft 17 of a conventional ROV drive bucket assembly 18, fits over the hex section 9 of the leadscrew, allowing the shaft to be normally rotated to close and open the clamp connector 1, by a ROV in well-known manner.

While the subsea connector shown has been modified in a number of respects as will become clear from the description below the features described above with reference to Figures ito 6 are well known.

A preferred embodiment will now be described with particular reference to Figures 7 to 13. Some of the feature set out below can also be seen in Figures 1 to 6 but have not been 9previously described.

The metal trunnions 10, 14 in a clamp connector as described above are modified to retain oil therein.

As best seen in Figure 9 each trunnion includes elastomeric thread seals 50, 55 held in recesses 52, 57 by metal retaining rings 51, 56 attached to the trunnion so as to prevent relative rotation therebetween. Ports 58 allow lubrication oil to be injected into the trunnion. An oil reservoir (not shown) connected to the port may be provided within the trunnion to increase the quantity of oil that can be stored therein.

Figures 7 to 13 show only the first trunnion. The first bore 11 is provided at a first end 60 thereof with a first annular recess 52 therein and at a second end 61 thereof with a second annular recess 57. First 50 and second 55 annular elastomeric thread seals each adapted to screw onto said first external thread are at least partially received respectively in said first and second annular recesses.

First and second annular metallic retaining rings 51, 56 which as shown each have an "L" shaped cross-section are each secured to the first trunnion so as to prevent relative rotation therebetween. As shown in Figures 7 and 13 screws 54 pass through apertures in the elastomeric thread seals 50, 55 and secure the metallic retaining rings 51, 56 to the trunnion so as to prevent any relative rotation therebetween.

The first and second annular metallic retaining rings 51 and 56 are adapted to pass over the first external thread in use retaining the first annular elastomeric thread seal in the first annular recess and the second annular elastomeric thread seal in the second annular recess. The first and second annular elastomeric seals retain the lubricating oil in said trunnion during opening and closing of the subsea clamp connector.

The second trunnion is not shown but is identical to the first trunnion (shown in Figures 7 to 13) except that the bore theretbrough (referred to below and in the claims as the second bore) is threaded on the opposite hand. The reason for this is to allow the clamp to close when the leadscrew is rotated (as is well known by a man of ordinary skill in the art) by a ROV in a first direction to close the subsea clamp connector or in a second direction to close the subsea clamp connector. Thus specific description and figures relating to the second trunnion are not considered to be necessary. Thus the bore through the second trunnion is referred to in the claims as said second bore and is provided at a first end thereof with a third annular recess and at a second end thereof with a fourth annular recess. Third and fourth annular elastomeric thread seals each adapted to screw onto said second external thread are at least partially received respectively in said third and fourth annular recesses. Third and fourth annular metallic retaining rings are each secured to the second trunnion so as to prevent relative rotation therebetween. The third annular metallic retaining ring is adapted to pass over the second external thread while retaining the third annular elastomeric thread seal in the third annular recess.

The fourth annular metallic retaining ring is adapted to pass over the second external thread while retaining the fourth annular elastomeric thread seal in said the annular recess.

As best seen in Figure 6 the known subsea clamp connector 1 includes a pair of mating male and female pipeline hubs 30, 31 and a sealring 32.

The sealring 32 provides in well-known manner a dual seal and may be a sealring sold under the Registered Trademark DUOSEAL.

The elastomeric seals may be formed from PTFE or (90 Shore Hardness) elastomer. Each thread seal may have a 10 mm thickness assuming 6mm pitch thread is used on the leadscrew.

The leadscrew may be provided with a splined rather than the usual hex end 7 and be driven by a drive spindle 17 of a ROV drive bucket assembly 18, the drive spindle including a splined socket which fits over said splined end. a

Claims

Claims A subsea clamp connector comprises; a leadscrew including a first threaded section having a first external thread and a second threaded section having a second external thread, said first and second external threads being threaded on opposite hands; a first generally cylindrical trunnion having a first bore extending substantially radially therethrough, said first bore being provided with a first internal thread such that said first trunnion is adapted to be screwed onto said first threaded section; a second generally cylindrical trunnion having a second bore extending substantially radially theretbrough, said second bore being provided with a second internal thread such that said second trunnion is adapted to be screwed onto said second threaded section; a chain of pivotally interconnected clamping segments including a first chain end segment and second chain end segments; said first chain end segment being provided with an aperture therein adapted to substantially house and allow rotation therein of said first trunnion; and said second chain end segment each provided with an aperture therein adapted to substantially house and allow rotation therein of said second trunnion; said first bore being provided at a first end thereof with a first annular recess and at a second end thereof with a second annular recess; first and second annular elastomeric thread seals each adapted to screw onto said first external thread and to be at least partially received respectively in said first and second annular recesses; first and second annular metallic retaining rings each secured to said first trunnion so as to prevent relative rotation therebetween, said first annular metallic retaining ring being adapted to pass over said first external thread while retaining said first annular elastomeric thread seal in said first annular recess and said second annular metallic retaining ring being adapted to pass over said first external thread while retaining said second annular elastomeric thread seal in said second annular recess; said second bore being provided at a first end thereof with a third annular recess and at a second end thereof with a fourth annular recess; third and fourth annular elastomeric thread seals each adapted to screw onto said second external thread and to be at least partially received respectively in said third and fourth annular recesses; third and fourth annular metallic retaining rings each secured to said second trunnion so as to prevent relative rotation therebetween, said third annular metallic retaining ring being adapted to pass over said second external thread while retaining said third annular elastomeric thread seal in said third annular recess and said fourth annular metallic retaining ring being adapted to pass over said second external thread while retaining said fourth annular elastomeric thread seal in said fourth annular recess.
2 A subsea clamp connector as claimed in claim 1 in which said leadscrew has a splined end and is driven by a drive spindle of a ROV drive bucket assembly, said drive spindle including a splined socket which fits over said splined end.
3 A subsea pipeline joint comprising a subsea clamp connector as claimed in claim 1, a pair of subsea pipeline hubs and a sealring.
4 A subsea pipeline joint as claimed in claim 3 in which said pipeline hubs are mating male and female hubs.A subsea pipeline joint as claimed in claim 3 in which said sealring forms a dual seal.