THIS INVENTION relates to apparatus for servicing under¬ water structures such as jetties, pylons, offshore oil and gas production platforms.

It is an object of the invention to provide a means for cleaning, inspecting and maintaining underwater structures whereby the apparatus can be positively secured to the structure and once in engagement be capable of self propulsion upon the structure.

In one form the invention resides in an underwater servicing apparatus comprising a part annular body, a plurality of arms extending to each side of the body and pivotally mounted thereto to be movable radially inwardly with respect to the central axis of the body, support elements mounted to said elements to facilitate engagement with a substantially cylindrical member which is to be partially surrounded by said body, a cleaning head mounted to said body for radial displacement inwardly therefrom and drive means for causing axial movement of the body along the cylindrical member.

According to a preferred feature of the invention at least one of said support elements are driven from said drive means.

According to a further preferred feature of the inven¬ tion the mounting for at least one of said support elements facilitate angular displacement of the body on the cylindrical member.

According to a further preferred feature of the inven¬ tion said cleaning head is mounted on said body to be capable of angular displacement around the inner

periphery of the body.

According to a further preferred feature of the inven¬ tion said cleaning head is supported on a slider which is slidably supported on the body to facilitate said angular displacement.

According to a further preferred feature of the inven¬ tion said cleaning head is mounted to said carrier through a pantograph-like arrangement associated with a drive to facilitate radial displacement of the cleaning head.

According to a preferred feature of the invention said cleaning head comprises an array of rotary cleaning elements wherein the rotation paths of said cleaning elements overlap.

According to an alternative preferred feature said cleaning head comprises at least two supports pivotally interconnected through an axially directed axis each supporting at least one cleaning element said supports being biassed to cause said cleaning heads to be brought into substantially equal engagement with the cylindrical member.

According to a further preferred feature of the inven¬ tion said support arms comprise a parallelogram like linkage between the body and support elements.

According to a further preferred feature of the inven¬ tion the apparatus has substantially a zero buoyancy.

According to a further preferred feature of the inven-

tion the apparatus is associated with an auxiliary articulated arm which is receivable on the body to be pivotal thereon and which is adapted to support a viewing means and/or tool, said auxiliary articulated arm being operable remotely.

According to a further preferred feature of the inven¬ tion said apparatus is associated with a weighted carrier supported from the surface which is adapted to support said apparatus when not in use, said carrier accomodating the power source for said apparatus and being interconnected therewith by an umbilical.

According to a further preferred feature of the inven¬ tion said apparatus is associated with a remotely operated vehicle capable of engaging the apparatus and carrying it between the carrier and substantially cylindrical member.

According to a further preferred feature of the inven¬ tion said remotely operated vehicle has inspection means.

According to a further preferred feature of the inven¬ tion said remotely operated vehicle is interconnected with the carrier through an umbilical to provide the power source required for the operation of the remotely operated vehicle.

The invention will be more fully understood in the light of the following description of one specific embodiment. The description is made with reference to the accompanying drawings of which:-

Figure 1 is a schematic view of the apparatus of the

embodiment associated with a support vessel;

Figure 2 is a substantially isometric view of the cleaning apparatus of the embodiment in use;

Figure 3 is an end elevation of the cleaning apparatus in the embodiment;

Figure 4 is a side elevation of the cleaning head and carrier therefor;

Figure 5 is a plan view of the cleaning head of the embodiment;

Figure 6 is a side elevation of the cleaning head of the embodiment.

The embodiment is directed to an apparatus for cleaning, inspecting and maintaining substantially cylindrical underwater structures such as pylons and piles and the support structure of offshore oil or gas production platforms. The embodiment comprises a support vessel 10, a carrier 11 which is to be suspended from the support vessel through a suitable cable 12, a remotely operated vehicle 13 associated with a secondary carrier 14 which is suspended from the vessel through a cable 14 and a cleaning and maintaining apparatus 15. The carriers 11 and 14 are provided with the necessary hydraulic pumps required for operation of hydraulic motors in the remotely operated vehicle 13 and cleaning apparatus 15 and are connected with their respective apparatus through an umbilical cord- 16 and 17 respectively whereby fluid pressure is supplied to the remotely operated vehicle 13 and cleaning apparatus 15 to operate hydraulic motors which effect the mechanical activities of each item. The necessary power to operate the hydraulic pumps on the carriers 11 and 14 is supplied thereto through electrical cables connected to the support vessel 10.

The cleaning apparatus 15 is engaged by the carrier 11 to facilitate transfer of the cleaning apparatus between the vessel 10 and the water and locating the cleaning apparatus 15 in close proximity to a structure to be cleaned. The carrier 11 is weighted in order to overcome any difficulties that may be overcome on the carrier and cleaning apparatus passing through the wave zone at the water surface. Similarly, the secondary carrier 14 facilitates transfer of the remotely operated vehicle 13 between the vessel 10 and the water and is weighted for similar reasons. When the carrier 11 is located adjacent a structure to be cleaned, the remotely operated vehicle 13 is disengaged from its secondary carrier and is caused to become engaged with the cleaning apparatus 15 at which time the cleaning apparatus 15 is disengaged from its carrier 11 and can be manipulated and located in position on the structure to be cleaned by the remotely operated vehicle 13.

The cleaning apparatus 15 comprises a partly annular body 20 having a plurality of swing arms 21 pivotally mounted thereto to extend substantially axially there¬ from. The swing arms 21 comprise a pair of subsantially parallel __rms each pivotally supported from the body 20 and interconnected at their other end by a bracket which supports a wheel 22 and hydraulic drive motor 23 for said wheel. The swing arms are movable radially with respect to the body and movement of the swing arms is effected through a hydraulic cylinder 24. The hydraulic cylinders 24 of each swing arm are connected in parallel whereby on pressure being supplied to the hydraulic cylinders is applied substantially equally to cause sub¬ stantially equal displacement of the swing arms 21 and

thus equal engagement of the wheels 22 with a cylindrical member 18 as shown at figure 2 whereby the cylindrical member 18 is engaged substantially concen¬ trically within the body 20. At least one of the wheels 22 is associated with a steering means to effect angular displacement of the wheel 22 on the support bracket and thus there is also angular displacement of the body 20 in the cylindrical member. The internal periphery of the body 20 is formed with a track 25 which slidably supports a slider 26 from which the cleaning head 27 is supported. The support for the cleaning head comprises a pantograph type arrangement which consists of a first arm 28 pivotally supported from one end of the slider 26 having a crank arm 29 extending from the end of the arm which is pivotally supported from the slider 26. The end of the crank arm 29 supports one end of a hydraulic ram 30 the other end of which is pivotally mounted to one end of a second arm. The other end of the second arm is pivotally mounted to a third arm 32 whereby the free end of the first arm 28 is pivotally mounted to an inter¬ mediate location on the third arm 32. The free end of the third arm 32 supports the cleaning head 27. On extension of the hydraulic ram 30 the resultant displace¬ ment between the first and second arms 28 and 31 causes the cleaning head to be brought into close abutting relationship with the slider 26 and on retraction of the hydraulic ram 30 the cleaning head is caused to be displaced radially away from the slider 26.

The cleaning head shown in the drawings comprises three support members pivotally interconnected through axially directed axes 36 and 37. A hydraulic ram 39 extends between the two outermost supports 33 and 35 to bias the supports 33, 34 and 35 into a substantially part

circular configuration. The support 33, 34 and 35 support a plurality of rotary cleaning element 38 each driven from a hydraulic motor 40 which are arranged such that on angular displacement of the cleaning head 27 around the body 20, the area cleaned by the cleaning elements 38 overlap. The rotary cleaning elements 38 may take any desired form to facilitate removal of debris marine growth from underwater structures.

According to an alternative arrangement of the cleaning head a plurality of cleaning elements which have over¬ lapping rotation paths may be mounted to one single support struture and have an axially orientation on the substantially cylindrical member 18 whereby on angular displacement of the cleaning head a swath of material can be removed by the single array of cleaning elements.

The body may be associated with an auxiliary articulated arm (not shown) which may be mounted to the exterior of the body to be pivotal therefrom and operable remotely. The free end of the auxiliary arm is adapted to accomodate a viewing means such as a video camera and/or a tool such as a cleaning head or welding head which can be used to service portions of the support structure away from the substantially cylindrical member supporting the body 20.

According to an alternative form the body 20 may comprise a pair of part annular beam members capable of relative angular displacement between each other whereby the cleaning head is carried by one of the beam members and the swing arms having the support elements thereon which is supported by the other of the beams.

In addition the support elements may take any desired means of supporting the body on the cylindrical member for movement therealong. Similarly the cleaning head aτid cleaning element may take any desirable form.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above.