Pipelines are installed between different subsea connections on the seabed for the offshore production of oil and gas. As it is not possible to use divers at great ocean depths, the pipelines are connected with the aid of special remote-controlled tools.

Today there is a wide selection of connectors and tools for this purpose. The connectors may have one or more ducts depending upon their intended use. It is customary to have one or two ducts, but in the case of control cables (umbilicals) there may be as many as ten pipes which are all to be connected simultaneously. One feature multi-duct connectors have in common is that they have a centrally mounted pipe having a diameter of from 50 to 150 mm. Around this lie electric cables and hydraulic lines having a diameter of up to about 25 mm. Optionally, the electric cables may be passed outside the mechanical connector and be connected separately.

It has been usual to use connectors where the fluid pipelines and optionally the electrical conductors run centrally through the connector so that the actual clamping mechanism is located on the outside of the pipe channels. It is known to use a so-called clamp connector with surrounding collars consisting of interarticulated arms or a collet connector consisting of many single fingers, or locking pawls, which encircle the pipe ducts and are actuated via an axially movable ring which surrounds the pawls or fingers.

This type of connector causes problems when the number of pipes to be connected is great and they are of"large"diameter. The pipes entering and exiting the connector must be bent in different directions in order to run clear of one another. There is very little space between the pipes and therefore very difficult to gain access in order to weld or screw the pipes in place. When many pipes are involved, an external collet connector will have a very large diameter making it unnecessarily large, heavy and costly. At the same time, there are liable to problems of misaligned pulling with a large lock ring.

In accordance with the present invention there is provided a connector of the type mentioned in the introduction which is characterised in that the pulling and locking

mechanism is positioned centrally in that the fluid flowlines and the optional electrical cables are positioned peripherally relative to said mechanism.

Each main component can advantageously include an annular part having an internal groove, which part surrounds the pulling and locking mechanism. Furthermore, the pulling and locking mechanism may include two or more pawls having radially projecting lugs for engagement with each groove in the annular parts on axial actuation by a wedge-acting mandrel which in turn effects radial movement of said pawl lugs.

Advantageously, at least one of the contact faces of the main components may be slightly conical in shape so that first contact between the contact faces takes place along their periphery. The contact faces may also be orientable relative to one another with the aid of guide pins.

Advantageously, one of the main components can include detachable sealing sleeves which are compressed or deformed on actuation of the pawl lugs. The sealing sleeves may be end-deformable against bevelled seats in respective main components. The bevelling of the sealing sleeves may be in the range of 30 to 50°, and preferably be about 46°.

Other and additional objects, features and advantages will be set forth in the description below of a currently preferred embodiment of the invention, which is given for the purposes of description without thereby defining the limits of the invention, and given in connection with the enclosed drawings, wherein: Fig. 1 shows the connector of the invention in longitudinal section, where the right-hand and left-hand halves show the connector in actuated and non-actuated state respectively; Fig. 2 shows in section the whole connector with the pulling and locking unit and pipes having respective choke valves; Fig. 3 shows a different longitudinal section through the connector 10 than that shown in Figs. 1 and 2; Fig. 4 shows a cross-sectional view along the line A-A in Fig. 2.

One embodiment of the invention will now be described with reference to Fig. 2 where a complete connector/choke unit for use in an oil and gas well with gas injection facilities is shown. This unit includes the actual connector 10, choke valves 18,18A with flowlines 5, 5A and an clamping unit 15 which is operable, e. g., by means of a tool in connection with a ROV. The tool on the ROV engages with a square section 16 on a screw having internal threads, which interact with external threads on an operating shaft 17 projecting down to the actual connector 10. This operating part per se does not constitute an essential part of the invention, and other types are fully possible, e. g., hydraulic cylinders.

In the illustrated embodiment the choke valves 18,18A are to be used to control the production from several wells. All the wells must have gas injection facility. This gas is passed via separate choke valves 18A on the unit back to the oil wells. This means that for each well, one oil choke valve 18 and one gas choke valve 18A are mounted on the unit. It must be possible to pull up the choke valves 18,18A for inspection and maintenance. In the embodiment described, two choke valves for gas and two for oil are to be mounted together on the connector/choke unit or module. This is to be disconnectable and retrievable to the surface as a unit. For this reason, each choke valve must be connected to a connector which has lead-through for incoming and outgoing oil or gas flow. The choke valves 18,18A are in turn to be controlled by means of hydraulic pressure. It is therefore necessary to have two hydraulic passages in the connector. Since four choke valves are to be mounted in each module it will be necessary to run 16 ducts through the connector.

Fig. 3 shows a different section through the connector 10 than that in Fig. 2. The only difference is that a guide pin 11 and a hydraulic control fluid line 19 are shown.

Fig. 4 shows a section through the dividing surface A-A in Fig. 2 to illustrate a typical example of what the distribution of flowlines through the connector may be like.

The connector 10 will now be described in more detail with reference to Fig. 1. The upper main component 2 of the connector 10 includes a cover 20 having a bushing and support for operating shaft 17. The upper main component 2 accommodates a mandrel 8 and a plurality of locking pawls 4. The locking pawls 4 and the mandrel 8 together constitute

the pulling and locking mechanism 1. On the right-hand side of the figure the mechanism 1 is in a locked position and on the left-hand side the mechanism is in an unlocked position. The pulling and locking mechanism 1 is actuated in that the operating shaft 17 with the mandrel 8 is passed downwards and the external surface of the mandrel rides on the contoured surfaces 4C on the inside of each pawl 4. When the mandrel 8 is moved axially, the pawls 4 are cam-guided so that they are turned about the groove 2B and the lug portions 4B are turned radially outwards into engagement with the groove or the shoulder 3B. The inclined planes that face each other on the pawl lugs 4A and 4B cause a powerful pulling together of the main components 2,3 so that sealed contact is obtained between the contact faces 2A and 3A.

On release of the connector 10, the mandrel 8 is pulled upwards once more and the upper portion of the mandrel thrusts against the cam surface on the internal pawl lug 4D which turns the pawl lug 4B radially inwards out of engagement with the shoulder or groove 3B.

The pawl lug 4A also turns a little, but not out of the groove 2B in the main component 2.

The main component 2 includes as mentioned a cover portion 20 screwed to the annular part 6 which includes the internal groove 2B. The annular part 6 also has pipe couplings 21A, 21B of different sizes and dimensions mounted thereon. The annular part 6 also includes a number of sealing sleeves 9 of various sizes and dimensions. Each sealing sleeve 9 consists of a metal sleeve, which is externally conical at both ends. The conical portion is designed for contact in seats 12 in the pipe coupling parts 21A and 21B, and also corresponding seats 12 in the lower main component 3. The lower main component 3 also includes an annular part 7 having said groove 3B or shoulder. Furthermore, the main component 3 includes pipe fittings 31A and 31B. The pipe fittings 31A and 31B include respective seats 12 for abutment against and interaction with sealing sleeves 9. The sealing sleeves 9 are a little longer than theoretical length. In this way, the sleeve is compressed, optionally deformed, during mounting and a pressure on the conical sealing faces is obtained which makes the seal gas and liquid-tight.

Other sealing systems may optionally be used together with the proposed connector 10.

The angle of taper a may advantageously be in the range of 30° to 50°.

One of the contact faces 2A, 3 A of the annular parts 6,7 may be slightly conical in shape so that the radial outer part of the contact faces 2A, 3A contact each other only when the main components 2,3 are pulled together. Thus, the annular parts 6,7 are pre-tensioned so much that there is no separation between the annular parts when the pipes and the seals passing through the connector 10 are pressurised.

It will be appreciated that the illustrated embodiment is of the type where the lower main component 3 is first attached to the bottom structure. Subsequently, the upper main component 2 is brought down from above by the operating device 15 and is landed and oriented with the aid of the guide pins 11 to ensure that the respective pipes 5 communicate with the correct pipes in the lower component 3.