GB2041301A - Submersibles - Google Patents

Abstract

A mobile submersible comprises two interconnectable chambers (1, 2) disposed one above the other and omnidirectional propelling means (7, 8). The upper chamber 1 is constructed to withstand hyperbaric submersion while its internal pressure is maintained at or close to atmospheric pressure, while the lower chamber 2 is constructed so that its internal pressure may be varied between atmospheric pressure and the pressure prevailing at hyperbaric operating depths. The submersible includes a variable buoyancy system operable from within one or both of the chambers. A plurality of propulsion units 7, 8 capable of moving and manoeuvring the submersible when it is submerged are provided, preferably by being attached to a housing in the form of a vertical cylindrical framework 3 located about the two chambers 1, 2 which can be strengthened to facilitate handling in rough weather. In use the submersible is connected to a surface vessel by an umbilical line 6. <IMAGE>

Description

SPECIFICATION Improvements relating to mobile diving units This invention relates to mobile diving units.

Diving units are frequently used in a variety of sea conditions where it is necessary for personnel to carry out inspection and/or work under water.

Conventional diving units are carried by a mother vessel to the site where they are to be used, and are then lowered to the location where inspection and/or work is to be carried out. This arrangement is inconvenient, since very accurate location of the diving unit is necessary. The present invention aims to provide a diving unit which is self propelled and offers more versatility than conventional diving units.

According to the present invention, there is provided a self-propelling mobile diving unit comprising two interconnectible chambers disposed one above the other, and means for connecting the diving unit to an umbilical line providing support facilities from a mother vessel at the surface, wherein (a) the upper one of the chambers is constructed to withstand hyperbaric submersion while an internal pressure at or close to atmospheric pressure is maintained within the said one chamber; (b) the lower of said two chambers is constructed so that its internal pressure may be varied between atmospheric pressure and the pressure prevailing at hyperbaric operating depths, and is provided with a port through which a diver may leave and re-enter the chamber; and (c) the diving unit is provided with a variablesbuoyancy system operable from within one or both of the chambers and with a plurality of propulsion units positioned and operable so as to provide omnidirectional manoeuvrability for the diving unit when it is submerged.

Advantageously, a vertically oriented housing is located about the two chambers, and serves to support the propulsion units. This housing is preferably adapted to provide protection for the two chambers in rough weather handling; to this effect, the housing can be formed of stiffened structural units disposed about the chanbers in the manner of a cage.

Preferably, the two chambers of the diving unit can function independently of one another; in one embodiment the chambers can be separated from one another while the diving unit is operating at hyperbaric depths. Under these conditions, one of the chambers will become detached from the housing, and therefore may lose its self-propulsion capability. Conveniently, the two chambers are generally spherical in form, and are mounted one above the other within the housing. The upper chamber can be referred to as an atmospheric control chamber.

Advantageously at least dne of the two chambers is provided with mating facilities whereby it can be connected to other submersible units, for example hyperbaric welding and/or maintenance units.

The lower chamber preferably incorporates life support and decompression facilities so that one or more divers can use both the upper chamber and the lower chamber when they are required to perform operations, such as welding or inspection of underwater structures, at hyperbaric depths.

Conveniently, the upper chamber will also have its own life support facilities.

Each of the chambers preferably includes observation windows.

Means are advantageously provided to enable a diver to work outside the diving unit while obtaining life support facilities from the umbilical line.

Preferabiy, the diving unit is provided with means whereby it can be located on the sea bed.

Such means can take the form of extendible legs which may be stowed aboard the diving unit when they are not required. It is also preferred to include in the diving unit means whereby the unit can be secured to a submarine structure, for example to part of an oil or drilling platform. In this case the means can be a clamping device which is rigidly secured to the diving unit and is able to grip the submarine structure tightly. One or more manipulators will generally be provided to assist the personnel operating from within the diving unit.

It is preferred to employ a plurality of propulsion units mounted on the housing. These provide omnidirectional mobility. Each of the propulsion units can provide a variable degree of thrust in a fixed direc.tion; alternatively individual thrusters may be directionally variable. With such an arrangement, it is convenient to provide a plurality (for example 4) units mounted to provide thrust in a horizontal plane. To provide complete manoeuvrability, the "horizontal thrusters" will be arranged in pairs the thrust direction of one pair being perpendicular to the thrust direction of the other pair. The propulsion units may be electric or hydraulic.

The housing can conveniently be cylindrical in shape. Communication facilities and general support systems, e.g. electrical power, heating water for diving suits, air for the upper chamber and a gas of appropriate composition for divers to breathe, will be provided to the housing and the two chambers by means of an umbilical line which passes between the diving unit and a surface mother vessel located close to the operation site at which the mobile diving unit is to work. The diving unit preferably also contains its own source or sources of power, and may be provided with radio communication equipment. In this way, continuous use of the umbilical line is not essential, although it may still be desirable for safety reasons and to- provide continuous power.

A diving unit in accordance with the present invention can be constructed so that it can move omnidirectionally without the necessity of rotating the diving unit first. Such rotation can, however, be performed where desired.

An emergency power supply will generally be provided in the diving unit.

Communication between the two chambers is desirable at all times. Since the two chambers may have different internal pressures, it is preferable to provide a communication line between the two chambers which can operate across a pressure seal.

The generally "vertical" mode of construction of a diving unit in accordance with the present invention is advantageous in that it enables improved mobility to be obtained. It also increases the recoverability of the unit.

By means of a diving unit in accordance with the invention, it is possible for an engineer to descend to hyperbaric depths in order to supervise non-destructive test procedures at close quarters and under atmospheric pressure from within the upper chamber of the diving unit.

Four a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a front elevation of one embodiment of the invention; Figure 2 is a plan view of the embodiment shown in Figure 1; Figure 3 is a cross section in a vertical plane through the embodiment of Figures 1 and 2; Figure 4 illustrates a second embodiment of the invention: Figure 5 shows the embodiment of Figure 4 connected to auxiliary apparatus: Figure 6 illustrates the embodiment of Figure 4 operating under different conditions; and Figure 7 illustrates the embodiment of Figure 4 secured to the leg of an offshore oil platform.

Referring to Figures 1 to 3, the diving unit comprises an upper chamber 1 and a lower chamber 2 supported in a housing 3. Port holes 4 are provided in bo.h of chambers 1 and 2. An access port 5 is provided on the upper surface of chamber 1. An umbilical connector 6 extends from the top surface of chamber 1 to a support vessel (not shown) located on the surface above the diving unit. Four propulsion units in the form of vertical thrusters 7 are provided close to the top part of housing 3, and a further four vertical thrusters 7 are located in a corresponding position at the base of housing 3. Two groups of four propulsion units 8 are similarly provided, but propulsion units 8 are positioned so as to provide thrust in a horizontal plane.As can be seen from Figure 2, each set of four thrust units 8 comprises two pairs of diametrally opposed units, the two pairs being set apart by 900 with respect to one another. In this way, movement in any desired direction can be achieved, as well as rotation of the diving unit. Each propulsion unit contains a hydraulically driven impeller capable of delivering variable thrust in a fixed direction. Referring to Figure 3, it can be seen that a port 9 is provided in the top part of lower chamber 2 whereby personnel may pass from the upper chamber 1 into the lower chamber 2, and vice versa. At the lower end of chamber 2, there is a pressure lock 10 communicating with the interior of chamber 2 via door 11, and communicating with the exterior of the diving unit via door 12. The pressure lock may contain an inert gas, for example helium.

Two or more ballast cylinders 30 are provided adjacent the lower chamber 2. In this embodiment, the cylinders 30 can be filled with water or the water can be displaced by the introduction of a gas, for example air or helium, which can be supplied from a support vessel via umbilical 6. Cylinders 30 thus act as a variable buoyancy system. The operation of the system is effected within the upper chamber 1.

As can be seen from the drawings, the housing 3 is cylindrical in form; upper chamber 1 has the form of an oblate spheroid; and lower chamber 2 is composite in shape, there being curved upper and lower parts 13 and 14, respectively, separated by a cylindrical intermediate portion 1 5.

The upper chamber 1 can be spherical.

Instead of employing external cylinders 30 as the buoyancy control system, the lower chamber 2 may be provided with internal tanks, for example "Q-tanks" -- which may be filled with gas and/or liquid in order to provide the desired degree of buoyancy.

Upper chamber 1 is constructed so that it can withstand hyperbaric submersion while its internal pressure is maintained at or close to atmospheric pressure. Lower chamber 2 is constructed to withstand hyperbaric pressures while providing a controlled and variable pressure within the chamber 2 itself. Chambers 1 and 2 can be separated from one another the lower chamber 2 passing out of housing 3 and thus losing its self propulsion capability. When chamber 2 is separated from the rest of the diving unit, a closure plate (not shown) is employed to seal off the lower part of chamber 1.

A wide variety of equipment may be installed within chambers 1 and 2. The equipment provided will depend upon the particular function which the diving unit is to perform. There will generally be equipment for communication between the diving unit and the surface on the one hand, and between chamber 1 and chamber 2 of the diving unit on the other hand. There will also generally be an emergency power supply and conventional safety equipment. The lower chamber 2 is advantageously constructed to function as a decompression chamber so that divers may enter and leave lower chamber 2 at will, to perform functions such as maintenance and inspection on sub-sea structures, and can undergo decompression while the diving unit is returning to the surface after a given task has been completed.

It will generally be convenient to construct the diving unit on a scale sufficient to allow three persons to occupy the upper chamber 1, and at least three persons to occupy the lower chamber 2. Larger or smaller units may be constructed as desired.

Referring now to Figure 4, an embodiment is illustrated which is generally similar to the embodiment shown in Figures 1 to 3, but in which the housing 3 is shaped differently to accommodate alternative propulsion units 7 and 8. The disposition of these units is the same as in the embodiment illustrated in Figures 1 to 3. As shown in Figure 4, the diving unit is descending from the sea surface 1 6 with the upper set of thrust units 7 operating to cause descent of the unit. At the same time, two horizontal thrust units are operating to move the diving unit to the left as seen in the Figure.

Referring now to Figure 5, the diving unit is shown connected to a welding module 1 7. A cylindrical tower 18 mounted on top of the generally spherical module 1 7 is mated with the air lock 10 at the base of lower chamber 2. With an arrangement of this sort, it is possible for the interiors of both lower chamber 2 and welding module 1 7 to be at atmospheric pressure.

Communication between chamber 2 and module 1 7 can then take place unhindered.

Referring next to Figure 6 the embodiment of diving unit shown in Figure 4 is illustrated resting on the sea bed 20 by means of support structures 21; these can be detachable from the diving unit, or may be collapsible and adapted for stowage under or within the mobile diving unit. A ladder 19 extends through air lock 10 to lower chamber 2, which in the condition illustrated is at ambient hyperbaric pressure. The lower chamber 2 is adapted to take three divers, one of whom is illustrated inside the lower chamber 2, while another is shown operating within a welding habitat 22. This habitat operates at ambient hyperbaric pressure, the lower face being open to the water. If support structures 21 are removed, the diving unit can be manoeuvred to mate with welding habitat 22 via locking member 23.

Referring lastly to Figure 7, the diving unit shown in Figure 4 is illustrated secured to a leg 24 of an offshore oil platform. This is achieved by a clamping mechanism 25 which is supported by the housing 3 and is controlled from within the diving unit. The clamp 25 provides a rigid connection between the diving unit and the platform. A line 26 is shown extending out of the diving unit to a diver 27 who is carrying out nondestructive test procedures on the platform structure. A second diver 28 within the lower chamber 2 supports the line 26, which is connected inside the diving unit with the output from the umbilical line 6, thereby providing the diver 27 with all the facilities he needs for carrying out his work. In the event that the umbilical line 6 is broken, diver 28 can reconnect line 26 to an emergency system (not shown) provided within the diving unit itself. A third person 29 monitors the progress of the testing procedure carried out by diver 27 from within the upper chamber 1; for this purpose, signals pass from tool 30 held by the diver 27 along a line 31 to a display/control panel 32 within the upper chamber 1.

Claims (17)

1. A self-propelling mobile diving unit comprising two interconnectable chambers disposed one above the other, and means for connecting the diving unit to an umbilical line providing support facilities from a mother vessel at the surface, wherein (a) the upper one of the chambers is constructed to withstand hyperbaric submersion while an internal pressure at or close to atmospheric pressure is maintained within the said upper chamber: (b) the lower of said two chambers is constructed so that its internal pressure may be varied between atmospheric pressure and the pressure prevailing at hyperbaric operating depths, and is provided with a port through which a diver may leave and re-enter the chamber; and (c) the diving unit is provided with a variable buoyancy system operable from within or both of the chambers and with a plurality of propulsion units positioned and operable so as to provide omnidirectional manoeuvrability for the diving unit when it is submerged.

2. A diving unit as claimed in claim 1, wherein a vertically oriented housing is located about said two chambers, which housing serves to support the propulsion units.

3. A diving unit as claimed in claim 2, wherein the housing is adapted to provide protection for the two chambers to facilitate handling in rough weather.

4. A diving unit as claimed in claim 1,2 or 3, wherein the two chambers can function independently of one another at hyperbaric depths.

5. A diving unit as claimed in claim 4, wherein the two chambers can be separated from one another while the diving unit is operating at hyperbaric depths.

6. A diving unit as claimed in any preceding claim, wherein both of the chambers are generally spherical in form.

7. A diving unit as claimed in any preceding claim, wherein at least one of the two chambers is provided with mating facilities whereby it can be connected to other hyperbaric facilities.

8. A diving unit as claimed in any preceding claim, which is provided with means whereby it can be located on the sea bed.

9. A diving unit as claimed in any preceding claim, which is provided with means whereby it can be secured to a submarine structure.

10. A diving unit as claimed in any preceding claim, wherein the lower chamber incorporates life support and decompression facilities for one or more divers.

11. A diving unit as claimed in any preceding claim, wherein the upper chamber incorporates life support facilities for one or more persons.

12. A diving unit as claimed in any preceding claim, wherein means are provided to enable a diver to work outside the diving unit while obtaining life support facilities from the umbilical line or from an emergency support system within the diving unit.

13. A diving unit as claimed in any preceding claim, wherein each of the propulsion units is adapted to provide a variable degree of thrust in a fixed direction.

14. A diving unit as claimed in any preceding claim, wherein observation windows are provided in both of the chambers.

15. A diving unit as claimed in any preceding claim, wherein the variable buoyancy system comprises one or more cylinders or tanks located within one of the chambers which cylinders or tanks can be filled with water which is displaceable by the introduction into the cylinders or tanks of a gas.

16. A diving unit as claimed in any one of claims 1 to 14, wherein the variable buoyancy system comprises one or more cylinders or tanks located on the exterior of one of the chambers of the diving unit and controllable from within the diving unit.

17. A diving unit substantially as hereinbefore described with reference to, and as illustrated in, Figures 1,2 and 3 of the accompanying drawings.

1 8. A diving unit substantially as hereinbefore described with reference to, and as illustrated in, Figures 4, 5 and 6 of the accompanying drawings.