GB2195412A - Fluid coupling - Google Patents

Abstract

A fluid coupling for underwater use has a stab 5 with one or more ports 7 on its outer circumference mating with a receptacle 24 having one or more ports 40, on its inner circumference. The ports on the stab are protected by a spring loaded sheath 10 and those on the receptacle by a spring loaded plug 30, the sheath and plug being displaced during mating. The ports are preferably annular and with stabs and receptacles having two or more ports. the ports may be at different levels in an axial direction as shown at 18,39 and 19,39. The coupling may be used to supply fluid (e.g. hydraulic fluid or gas) to any underwater equipment and can be used in any orientation. The use of circumferential ports means that there are no axial fluid forces on the coupling during mating or release. Variations for high and low pressure use are shown on the left and right hand sides of the figure respectively. <IMAGE>

Description

SPECIFICATION Fluid coupling This invention relates to a fluid coupling for underwater use, suitable, for example, for supplying a liquid, such as hydraulic fluid or for supplying a gas, to an underwater well or subsea equipment. Gas may be needed, for example, for nitrogen injection, gas injection or artificial lift.

In the use of hydraulic power in underwater wells or subsea equipment, there will necessarily be one or more couplings in the hydraulic fluid supply system, and it is, obviously, of crucial importance that such couplings should be fluid tight, preventing egress of hydraulic fluid or ingress of sea water. In the case of couplings which can be made up or released underwater it is also, obviously, important that the couplings should be fluid tight before mating and after mating as well as when in use.

For convenience, the coupling of the present invention will be described with reference to the supply of a liquid, viz hydraulic fluid, but it will be apparent that the same need for fluid tightness will apply for the supply of other liquids or for gases.

There may be a number of parts of an underwater well system which require hydraulic power to actuate them. Some may require high pressure hydraulic power and some low pressure. A single coupling with several hydraulic flow lines passing through it would be particularly useful, therefore, so as to reduce the total number of couplings required.

The present invention is concerned with a fluid coupling of the stab and receptacle type which can be mated and released under water and which may have multiple fluid lines passing through it.

According to the present invention a fluid coupling suitable for underwater use comprises (a) a stab having one or more ports for fluid on its outer circumference, (b) a spring loaded sheath covering the port or ports when the stab is not mated, (c) a receptacle for the stab having one or more ports for fluid on its inner circumference, (d) a spring loaded plug covering the port or ports when the receptacle is not mated, (e) means for moving the spring loaded sheath and spring loaded plug when the stab and receptacle are mated so that the ports in the stab and receptacle are aligned to provide a path for fluid from the stab to the receptacle, and (f) seals on either side of the port or ports to make the ports fluid tight before and after mating.

The stab may be splined into a housing which may be loosely aligned with a floating base plate. The receptacle may also be loosely aligned with a structural base plate, thereby giving a degree of movement for the -stab and receptacle to assist in mating and bringing the ports in the stab and receptacle into conjunction.

For a fluid coupling with only a single fluid line there may be only single ports in the stab and receptacle. These can be annular thereby avoiding the need for any special alignment in the rotational sense. There will be a fluid supply passage in the stab leading to the port and this may be a central passage. There will also be a fluid passage in the receptacle leading from the port and this may be an annular passage around the receptacle.

With fluid couplings having two or more fluid lines, there will be two or more ports in the stab and receptacle.

These ports may be positioned around the circumference of the stab and receptacle at the same axial level. With this configuration it is preferable that the stab and receptacle are orientated so that the ports match up when the stab and receptacle are mated to maximise the flow rate. Preferably therefore the ports are at different levels in an axial direction on both the stab and receptacle. The ports can then be annular as with a single fluid line connector with suitable machined passages from sectors of the annuli connecting up the annuli to the axial fluid supply passages.

In a particularly preferred embodiment, a three fluid line coupling may have three bores for fluid in the stab, spaced equilaterally within it, with three axially-displaced passages from them leading to axially-displaced annular ports.

The receptacle will have three similarly axiallydisplaced annular ports with three separate passages leading away from them to fluid outlet lines around the receptacle.

When the fluid is hydraulic fluid, the hydraulic lines may be all high pressure (eg of the order of 10,000 psi) lines or all low pressure lines (eg of the order of 1500 psi), or a com bination. For high pressure fluid the lines and ports may be smaller (eg 3/8 inch diameter bore) with the seals duplicated in all situations. For the low pressure fluid the lines and ports may be larger (eg 1 inch diameter bore) and the seals between the porta may be single.

The end of the stab may be concave. The end of the receptacle and of the plug may be convex with a similar profile to the concave end of the stab, thereby assisting in alignment during mating. The convex end to the plug and receptacle helps to prevent deposition of debris when the receptacle is not mated. De position of debris in the concave end of the stab will be less likely since this will be pro tected by the sleeve. Further it will be the stab which will be moved to the receptacle and it will, therefore, be less at risk from the deposition of debris.

The fact that the ports are circumferentially placed around the stab and receptacle eliminates any axial fluid forces during operation.

The spring for the sleeve of the stab may be within an external housing surrounding the stab.

The space below the plug of the receptacle into which it slides during mating may be filled with a suitable fluid (eg hydraulic fluid), the fluid being displaced into a balance chamber from which it can return on release of the parts of the coupling. The plug may slide on a central stem within the receptacle. There may also be fluid within the plug with a suitable vent to the space below.

There should be no pressure in the lines during mating or release.

The coupling may be mounted around modular connectors or form part of a junction plate between subsea modules.

The invention is illustrated with reference to the- accompanying drawings in which: Figure 1 is a vertical section through a stab component of a hydraulic coupling with three hydraulic lines.

Figure 2 is a vertical section through a receptacle component of a hydraulic coupling with three hydraulic lines.

Figure 3 is a vertical section through the mated stab and receptacle components of Figures 1 and 2, and Figure 4 is a horizontal section through the mated stab and receptacle components of Figures 1 and 2.

Although the drawings show the stab and receptacle in vertical positions, the coupling can operate in any position from the vertical to the horizontal.

In Figure 1, the stab 5 has a bore 6 for a supply of hydraulic fluid with a sector shaped passage 58 (see Figure 4) leading to an annular port 7 on the outer circumference of the stab. On the left hand side of the drawing the bore 6 is for high pressure fluid; on the right hand side it is for low pressure fluid. (It will be appreciated that the showing of both types of passage is diagrammatic only. A section through an actual coupling would show only one bore. This diagrammatic depiction illustrates, however, that bore 6 and port 7 for high pressure fluid are narrower than those for low pressure fluid).

Stab 5 is loosely positioned in a structural plate 8 which forms part of a suitable piece of underwater equipment. Stab 5 has a degree of axial movement with respect to structural plate 8. Its lower end has a concave cap 9.

Surrounding the end of the stab is a sheath 10 which covers port 7. Sheath 10 is springloaded by spring 11 which extends into spring housing 12 attached to the upper part of stab 5 by means of spring housing plate 13. Orientation pin 14 on the sheath cooperates with slot 15 in the stab. The gap between spring housing plate 13 and structural plate 8 represents the extent of axial movement of the stab with respect to plate 8.

The sheath 10 has further orientation pins at 16 and a floating base plate 17, the pins orientating the sheath with respect to the floating base plate 17. Floating base plate 17 may be correctly orientated on the underwater equipment with respect to the structural plate 8 by guide pins or keys (not shown) which align with the structural plate 8.

The stab has two further annular ports 18,19 above port 7 which are for two further hydraulic bores in the stab. These three hydraulic passages are equilaterally positioned within the stab (as shown in Figure 4).

A double seal 20 in the stab cap 9-seals the stab with respect to the sleeve. There are also seals 21,22,23 in the stab above ports 7,18 and 19. On the left hand side, illustrating a high pressure hydraulic line, the seals are double; on the right hand side, illustrating a low pressure hydraulic line, the seals are sin gle above ports 7 and 18, but are double above port 19.

Figure 2 shows the receptacle into which the stab of Figure 1 is mated. As with Figure 1, it is a composite figure, the left hand side of the figure showing the arrangement of passages for high pressure hydraulic fluid and the right hand side the passages for low pressure hydraulic fluid.

Figure 2 shows receptacle 24 with inner sleeve 25 and outer sleeve 26, the latter sleeve being held against inner sleeve 25 by a screw thread. Lock nut 27 holds the receptacle coupling within the base plate 51. Outer sleeve 26 has a bore for the hydraulic fluid.

On the left hand, high pressure side, a single bore 28 is shown; on the right hand, low pressure side, there are in fact four bores (see Figure 4) one being shown in Figure 2 as bore 64C. Inner sleeve 25 has an angled top 29.

Within receptacle 24 is a plug 30, formed of a sleeve 31 and convex cap 32 which is angled at its edges to align with the angled top 29 of the receptacle inner sleeve 25. Plug 30 is completed by a sliding base 33 which is free to slide within plug 30 on a stem 34 screwed into a base plate 35 of the receptacle 24. There is a spring 36 between sliding base 33 and receptacle base plate 35 and another spring 37 between plug cap 32 and sliding base 33.

Receptacle 24 has an annular port 38 on its inner circumference communicating with bore 28 by a crescent shaped passage 61 (see Figure 4). As in Figure 1, the left hand side of the drawing illustrates diagrammatically a small port for high pressure hydraulic fluid and the right hand side shows a larger port for low pressure hydraulic fluid. In practice only one bore and port would be seen in an actual true section.

Further ports 39,40 are shown further down receptacle 24, these being ports for two other hydraulic fluid lines, communicating through passages with other bores corresponding to bore 28 (see Figure 4).

Plug 30 has double seals 41,42 at top and bottom. There are also seals 43 between ports 38 and 39 and seals 44 between ports 39 and 40. These are shown as double seals on the left hand, high pressure side and single seals on the low pressure right hand side.

Since receptacle 24 is formed of inner and outer sleeves there are also seals (45,46,47,48) between these inner and outer sleeves above, below and between the ports.

These are double at each end but the intermediate seals are shown as double or single depending on whether they are sealing high or low pressure ports.

The space within receptacle 24 below plug 30 has a line 49 to a balance chamber. The space is filled with hydraulic fluid which is displaced during mating into the balance chamber. The space within plug 30 is also filled with hydraulic fluid, there being vent holes in sliding base 33 communicating with the space below the plug and hence with the balance line 49. To prevent a hydraulic lock occurring when plug 30 bottoms out a side vent 52 is provided.

Receptacle 24 may be part of any suitable piece of underwater equipment. It has orientation pins 50 and a structural base plate 51, the pins 50 orientating the receptacle with respect to the base plate 51. This base plate 51 may be orientated to line up with base plate 17 (Figure 1) of the stab portion of the coupling.

Figure 3 shows the mated stab and receptacle of Figures 1 and 2 with the ports indicated by the same numerals as in Figures 1 and 2. It will be seen that, during mating, the concave cap 9 of stab 5 pushes against the convex cap 32 of plug 30 axially aligning the plug 9 with the receptacle 30 and then forcing the plug down against the force of springs 36 and 37 into the receptacle 24. At the same time receptacle 24 pushes stab 5 first up against structural plate 8 and then pushes sheath 10 surrounding stab 5 up into housing 12 against the force of spring 11. Ports 7,18,19 on the stab become aligned with ports 40,39 and 38 respectively of receptacle 24 thereby allowing hydraulic fluid to pass from the stab to the receptacle.

Figure 4 shows the disposition of the three hydraulic lines. It will be seen that stab 5 has three bores, viz bore 6 shown in Figure 1 for high pressure and also bores 53 and 54 drilled through it, in the low pressure configuration, equilaterally. This drawing shows 1/3 of a high pressure coupling and 2/3 of a low pressure coupling.

Bore 6 communicates with annular port 7 through a sector-shaped passage 58. Similarly bores 53 and 54 communicate with annular ports 18 and 19 through sector-shaped passages 59 and 60.

In the receptacle 24, annular port 40 communicates with bore 28 through a crescentshaped passage 61. The bore 28 is for high pressure hydraulic fluid and is of narrow diameter. The hydraulic fluid exits from bore 28 through a plug outlet 55. There are similar crescent-shaped passages 62,63 from annular ports 38 and 39 leading to bores 64 and 65.

These ports, passages and bores are shown in Figure 4 as being for low pressure hydraulic fluid (ie of relatively large flow capacity). To give this relatively large flow capacity for bores 64 and 65 while keeping the receptacle of relatively small dimensions, bores 64 and 65 actually consist of 4 separate bores marked A, B, C and D respectively. These bores lead into outlets 56 and 57. Passages 66 and 67 drilled into the body of the receptacle are the means of communication between bores 64 and 65 and outlets 56 and 57, each being sealed with a plug 68,69.

Claims (8)

1. A fluid coupling suitable for underwater use comprising (a) a stab having one or more ports for fluid on its outer circumference, (b) a spring loaded sheath covering the port or ports when the stab is not mated, (c) a receptacle for the stab having one or more ports for fluid on its inner circumference, (d) a spring loaded plug covering the port or ports when the receptacle is not mated, (e) means for moving the spring loaded sheath and spring loaded plug when the stab and receptacle are mated so that the ports in the stab and receptacle are aligned to provide a path for fluid from the stab to the receptacle, and (f) seals on either side of the port or ports to make the ports fluid tight before and after mating.

2. A fluid coupling as claimed in claim 1 wherein the porta of the stab and receptacle are annular.

3. A fluid coupling as claimed in claim 1 or 2 wherein the stab and receptacle each have two or more ports at different levels in an axial direction.

4. A fluid coupling as claimed in claim 1, 2 or 3 for transmitting hydraulic fluid wherein one or more of the ports is for high pressure hydraulic fluid and one or more of the ports is for low pressure hydraulic fluid.

5. A fluid coupling as claimed in any of claims 1 to 4 wherein the the end of the stab is concave and the end of the plug of the receptacle is convex.

6. A fluid coupling as claimed in any of claims 1 to 5 wherein the stab is positioned on a structural plate and has a degree of axial movement relative to the plate.

7. A fluid coupling as claimed in any of claims 1 to 6 wherein the plug of the receptacle slides on a central stem within the recep tacle.

8. A fluid coupling according to claim 1 was hereinbefore described with reference to Figures 1 4 of the accompanying drawings.