GB2541219A - Apparatus and method for scanning a structure - Google Patents

Apparatus and method for scanning a structure Download PDF

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Publication number
GB2541219A
GB2541219A GB1514320.9A GB201514320A GB2541219A GB 2541219 A GB2541219 A GB 2541219A GB 201514320 A GB201514320 A GB 201514320A GB 2541219 A GB2541219 A GB 2541219A
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GB
United Kingdom
Prior art keywords
apparatus
centre
buoyancy
actuator
position
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
GB1514320.9A
Other versions
GB201514320D0 (en
Inventor
John Beckett Oliver
Falconer Robert
Wallace Morris Robert
Michael Thomas Lee
Wilson Brian
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Johnson Matthey PLC
Original Assignee
Johnson Matthey PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Johnson Matthey PLC filed Critical Johnson Matthey PLC
Priority to GB1514320.9A priority Critical patent/GB2541219A/en
Publication of GB201514320D0 publication Critical patent/GB201514320D0/en
Publication of GB2541219A publication Critical patent/GB2541219A/en
Pending legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B63SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63CLAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
    • B63C11/00Equipment for dwelling or working underwater; Means for searching for underwater objects
    • B63C11/52Tools specially adapted for working underwater, not otherwise provided for
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B63SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63GOFFENSIVE OR DEFENSIVE ARRANGEMENTS ON VESSELS; MINE-LAYING; MINE-SWEEPING; SUBMARINES; AIRCRAFT CARRIERS
    • B63G8/00Underwater vessels, e.g. submarines; Equipment specially adapted therefor
    • B63G8/14Control of attitude or depth
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/06Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption
    • G01N23/18Investigating the presence of flaws defects or foreign matter
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B63SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63GOFFENSIVE OR DEFENSIVE ARRANGEMENTS ON VESSELS; MINE-LAYING; MINE-SWEEPING; SUBMARINES; AIRCRAFT CARRIERS
    • B63G8/00Underwater vessels, e.g. submarines; Equipment specially adapted therefor
    • B63G8/001Underwater vessels adapted for special purposes, e.g. unmanned underwater vessels; Equipment specially adapted therefor, e.g. docking stations
    • B63G2008/002Underwater vessels adapted for special purposes, e.g. unmanned underwater vessels; Equipment specially adapted therefor, e.g. docking stations unmanned
    • B63G2008/004Underwater vessels adapted for special purposes, e.g. unmanned underwater vessels; Equipment specially adapted therefor, e.g. docking stations unmanned autonomously operating
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00Investigating materials by wave or particle radiation
    • G01N2223/60Specific applications or type of materials
    • G01N2223/628Specific applications or type of materials tubes, pipes

Abstract

An apparatus 1 for scanning a subsea structure has an axis A that aligns with the axis of the structure when in use, and a centre of buoyancy laterally offset from, and moveable with respect to, the centre of mass. The apparatus comprises a frame 2 and a buoyancy material 3 which moves relative to the frame along the axis. An actuator 5 moves the material between a first position in which the centre of buoyancy is substantially axially aligned with the centre of mass and a second position in which it is axially offset therefrom. The movement of this material changes the trim of the device whilst in the water, allowing parts of a structure with different orientations to be scanned. The apparatus may be used to examine for integrity issues such as cracking or fatigue in structures such as pipelines.

Description

APPARATUS AND METHOD FOR SCANNING A STRUCTURE Field of the Invention

The present invention relates to an apparatus and method for scanning subsea structures, such as subsea pipelines.

Background

Subsea structures are used extensively in the offshore industry. Such structures include pipelines, cables, umbilicals, piggy-back pipeline structures and structural members such as platform legs.

For example, subsea pipelines are used extensively in the oil and gas industry to transport fluids, including liquids and gases, across the sea bed and from the sea bed to topside installations. Over time structures such as pipelines may encounter asset integrity issues such as corrosion, cracking or fatigue. Such issues can result in weakening of the structures and increase the risk of a structure failing. If this cannot be quantified it can lead to reduced lifetimes as a result of the need to allow a margin of safety to account for the unknown extent of the issue. For example, in the absence of information about the true state of the pipeline, an operator may reduce the pressure of a pipeline or estimate a lifetime based on models of the likely pipeline condition. However, providing real data about the condition of a specific part of the pipeline may allow the condition of the pipeline to be determined with greater accuracy, potentially allowing the lifetime to be extended or the operating conditions maintained. On the other hand, real data may identify issues that models have failed to predict and may avert failures of the pipeline. Some structures, for example pipelines, may also experience flow assurance issues during their lifetime. For example deposits such as gas hydrates may build up on the inner walls of pipelines reducing the effective cross-section of the pipe available for flow. Identification of the location of blockages or of the rate of deposit build up may allow operating conditions to be altered to extend the lifetime of the pipeline. Additionally, information about the rate or extent of deposit formation may allow the interval between maintenance and cleaning shutdowns to be optimised, thus improving the economics of operating the pipeline.

In order to obtain data about the condition of subsea structures, various scanning instruments have been developed. It is advantageous to be able to inspect a structure such as a pipe while it is operating and regardless of the existence of any restrictions, such as valves or junctions. That may be particularly the case subsea where access points into the structure may be infrequent. Thus it is advantageous to be able to scan the structure from outside. A number of scanning instruments are able to do that. For example, an apparatus for scanning structures such as a subsea pipeline using gamma radiation is described in GB2496736. This apparatus comprises a source of gamma radiation and an array of detectors spaced apart circumferentially. The apparatus is capable of being arranged with the pipeline to be scanned positioned between the source and detectors so that radiation emitted by the source can pass along the plurality of paths through a portion of the structure to the detectors. The number of detectors in the array may range from fewer than 10 up to more than 100, e.g. up to 150, depending on the application. Counting the number of gamma photons transmitted from the source to the detectors, through the pipeline being scanned, enables differences in the density of different parts of the structure to be detected. A scanning apparatus, such as that described in GB2496736, will typically clamp onto the structure to be scanned, although some apparatus may be designed to be held in the vicinity of the structure by an ROV. Even where the apparatus clamps onto the structure, it may still need to be manoeuvred into position to clamp onto the structure by an ROV. In orderto protect the apparatus as it is lowered into the water, through the so-called splash zone, the apparatus may be lowered in a basket and then removed from the basket by the ROV for deploying onto the structure.

An ROV typically has two manipulators, which can grasp handles on the apparatus. The manipulators can apply twisting or lifting forces to the apparatus relative to the ROV and the ROV can also be moved by its thrusters, thus carrying the apparatus along with it. However, since there is a limit to the size of the force that can be applied via the manipulators to the apparatus it is usually necessary to add buoyancy to the apparatus to reduce the weight of the apparatus in water and to trim the apparatus so that it has a preferred orientation. The location of the centre of buoyancy relative to the centre of mass will determine the orientation at which the apparatus lies in the water. In order to improve the handling, the apparatus will usually be trimmed so as to have some weight in water and thus will slowly sink unless supported by the ROV. The force applied by the ROV to keep the apparatus stationary in the water, and the position at which that force is applied, may also affect the angle at which the apparatus lies in the water when held by the ROV.

In orderto reduce the strain on the ROV, it is preferable to keep twisting forces being applied by the ROV to a minimum. Minimising the need for twisting forces may also allow for more straightforward handling by ROVs with limited functionality in their manipulators. With that in mind it is known to fit the apparatus with buoyancy designed to trim the apparatus to lie in a favourable orientation for the scanning task to be performed. For example, it is known to provide pockets in the buoyancy of scanning apparatus that can be filled with either weights or blocks of buoyancy as required in order to tune the trim of the apparatus to a particular angle. While such a as system can produce a stable trim of the apparatus the trim can only be changed by bringing the apparatus back on deck and adjusting the weights and buoyancy blocks. That may increase the time required for scanning tasks involving both horizontal and vertical structures. It may also lead to issues where the basket in which the apparatus is lowered through the splash zone accommodates the apparatus in a different orientation to that required for the scanning task. For example, the basket will typically be designed to accommodate the apparatus in a particular orientation in which it can be securely fastened in the basket. If that orientation is horizontal, but the structure to be scanned is vertical, there may be difficulties in removing the apparatus from the basket and onto the structure or from the structure back into the basket if the apparatus can only be trimmed for one of the orientations.

In subsea applications, additional constraints arise. When operating at a depth of 1000 metres underwater, the pressure is 100 atmospheres and increases by a further 100 atmospheres for each additional 1000 metres of depth. The apparatus must be able to withstand this pressure yet remain sufficiently compact for deployment using remotely operated vehicles capable of operating at the required depth. It is particularly preferable for the apparatus to be able to withstand the pressure at a depth of 3000 m so that offshore assets at that depth can be scanned.

Preferred embodiments of the present invention seek to overcome one or more of the above disadvantages of the prior art.

Summary of Invention

According to a first aspect of the invention, there is provided an apparatus for scanning a subsea structure, the apparatus having: an axis that aligns with the axis of the structure in use, a centre of mass, and a centre of buoyancy laterally offset from the centre of mass; wherein the apparatus comprises: a frame, buoyancy material mounted for axial movement relative to the frame, and an actuator configured to move the buoyancy material between a first axial position in which the centre of buoyancy is substantially axially aligned with the centre of mass and a second axial position in which the centre of buoyancy is axially offset from the centre of mass.

By providing buoyancy material mounted for axial movement relative to the frame and an actuator configured to move the buoyancy material from a first axial position in which the centre of buoyancy is substantially axially aligned with the centre of mass and a second axial position in which the centre of buoyancy is axially offset from the centre of mass, the trim of the apparatus can be adjusted by actuating the actuator to move the buoyancy material from the first axial position to the second axial position. For example, in the first axial position the centre of buoyancy of the apparatus is substantially axially aligned with the centre of mass of the apparatus. In that configuration the apparatus may tend to lie in the water with the axis generally horizontal, with the rotational stability of the apparatus determined by the lateral offset of the centre of buoyancy from the centre of mass (in the absence of external forces, the apparatus will lie with the centre of buoyancy vertically above the centre of mass). In some embodiments there may be no lateral offset, in which case the apparatus may lie in any rotational position with the axis generally horizontal. However, in order to fully stabilise the apparatus in a horizontal orientation there is preferably a lateral offset. By moving the buoyancy to the second axial position the axial location of the centre of buoyancy may be changed by a significantly greater amount than the centre of mass (since the buoyancy material has a greater effect on the centre of buoyancy than on the centre of mass). As a result the trim of the apparatus may change so that the apparatus now lies with the axis at an angle to the vertical, for example not more than 10 or 20 or 30 or 40 degrees to the vertical.

It will be understood that the terms “axial” and “lateral” refer to a coordinate system based on the axis of the apparatus. Thus an axial offset is the component of an offset in the direction of the axis of the apparatus and a lateral offset is the component of an offset in a direction perpendicular to the axis. Two locations may be both laterally and axially offset from each other in that the offset has components in both the lateral and axial directions.

The ability to actuate an actuator and thus adjust the trim of the apparatus means that the trim can be adjusted while the apparatus is deployed underwater. For example, the trim could be altered ‘mid-water’ (i.e. when the apparatus is under the water but not attached to a structure or secured in a launch basket). Preferably the actuator is a remotely controlled actuator. In that way the trim can be adjusted by an operator on the surface directly, without, for example, having to manipulate the actuator using the ROV. Most preferably the actuator is a hydraulic actuator. For example the hydraulic actuator may be a hydraulic cylinder. Preferably the speed of actuation of the actuator can be controlled. In that way the speed of re-orientation of the apparatus when the trim is adjusted can be controlled. That may be important as a sudden change of orientation could result in excess loading of an ROV manipulator holding the apparatus. More preferably, the actuator may be configured such that the actuator can move the buoyancy material to a position between the first and second positions. For example, the actuator may comprise a feedback system so that the operator can monitor the position of the actuator and adjust it to a desired position. Whilst the invention provides significant benefits even if the buoyancy material is movable from the first position to the second position, the invention may provide further advantages if intermediate positions can be selected, thus permitting the apparatus to be trimmed to a variety of angles. Preferably, when the actuator is a hydraulic actuator the apparatus comprises a proportional valve hydraulically linked to the hydraulic actuator so that control of the proportional valve controls the speed of actuation of the hydraulic actuator.

Preferably the apparatus comprises a plurality of ROV handles (i.e. handles that can be grasped by the manipulator of an ROV). Preferably the apparatus comprises at least one ROV handle positioned at an end of the apparatus toward which the buoyancy material is moved when moving from the first position to the second position. Thus the handle is preferably at the upper end of the apparatus when the apparatus is lying with the centre of buoyancy above the centre of mass with the buoyancy material in the second position.

Preferably the apparatus includes biasing means, for example springs, which urge the buoyancy material from the second position to the first position. The actuator may move the buoyancy material from the first position to the second position against the urging of the biasing means. That may be advantageous in that, in the event of actuator failure, for example hydraulic failure, the biasing means will act to return the buoyancy material to the first position and thus re-orientate the apparatus to the horizontal position. Of course, if the default orientation of the apparatus is vertical, then the biasing means may urge the buoyancy material from the first position to the second position and the actuator may move the buoyancy material from the second position to the first position against the urging of the biasing means. It will be appreciated that even if the biasing means are present the actuator may still be the primary means of moving the buoyancy material from the first position to the second position and back.

Preferably a plurality of actuators is provided. Providing a plurality of actuators may allow the load to be distributed more evenly across the frame when moving the buoyancy material and result in a smoother axial movement. The buoyancy material may be a single block of material but is preferably two blocks of material. Having two blocks of material may be particularly advantageous in an apparatus that opens, for example in a clam shell arrangement, in order to fit onto pipelines.

In that situation one block of buoyancy material may be provided on each side of the opening in the apparatus. It will be appreciated that each ‘block’ may be a monolithic block or may a plurality of monolithic blocks fastened together so as to move as a single block. Preferably the buoyancy material moves by sliding along guides, for example rods mounted to the frame and extending through the buoyancy material. Preferably the guides include end stops to limit the movement of the buoyancy material. Sliding the buoyancy material on such guides may provide a robust system of providing linear axial movement of the buoyancy material without requiring precise alignment and positioning of the actuators. That may be important as the frame of the apparatus may be supporting many other components, such as detectors, electronics and hydraulics and it may not therefore always be possible to locate the actuator in the optimal position to provide linear axial movement in the absence of guides. The apparatus may comprise further buoyancy material that is not moved by the actuator. For example, in some embodiments buoyancy material may be provided at either end of the apparatus and the actuator may be configured to move the buoyancy material at one end of the apparatus. It will be appreciated that moving only some of the buoyancy material on the apparatus may still be sufficient to alter the orientation of the apparatus.

According to a second aspect of the invention there is provided a method of scanning a subsea structure, the method comprising providing an apparatus at a subsea location, the apparatus having an axis, a centre of mass, and a centre of buoyancy laterally offset from the centre of mass; operating an actuator to move buoyancy material mounted on the apparatus between a first axial position in which the centre of buoyancy is substantially axially aligned with the centre of mass and a second axial position in which the centre of buoyancy is axially offset from the centre of mass; and scanning the subsea structure with the axis of the apparatus aligned with the structure.

By operating the actuator and moving the buoyancy, the trim of the apparatus is adjusted. That may be useful in several scenarios, including where the apparatus is lowered into the water in one orientation but is being used to scan a structure, such as a pipeline, in another orientation or where the apparatus is required to scan different sections of structure at different orientations. For example, the method may include the steps of scanning a first section of a structure at a first orientation, operating the actuator to move the buoyancy material mounted on the apparatus between the first axial position and the second axial position, and scanning a second portion of a structure at a second orientation. It will be appreciated that moving the buoyancy material between the first position and the second position may involve moving the buoyancy material from the first position to the second position or moving the buoyancy material from the second position to the first position. Preferably the orientation of the first section of structure is horizontal and the orientation of the second section of structure is vertical, in which case the buoyancy material would be moved from the first position to the second position.

Preferably the structure is a pipeline. It will be appreciated that a pipeline may have at least a local axis and that the axis of the scanning apparatus may be aligned with the axis of the pipeline. Pipeline scanning may particularly require both horizontal (for seabed pipelines) and vertical (for risers) orientations and the invention may therefore be particularly advantageous in a pipeline scanning apparatus. For example the apparatus may be used to scan a horizontal portion of pipeline and then a vertical portion of pipeline, or vice versa, without having to return to the surface for re-trimming.

Preferably the apparatus is provided mid-water. For example the apparatus may be provided midwater by deploying the apparatus in a basket from a surface vessel, lowering the apparatus in the basket through a splash zone, and removing the apparatus from the basket, preferably using an ROV. The ability to alter the trim of the apparatus mid-water may be a significant advantage over prior art systems in which the apparatus is returned to the surface and lifted out of the water to adjust the trim.

Preferably the method comprises supporting the apparatus in a first orientation by grasping a first handle with an ROV, operating the actuator to move the buoyancy material mounted on the apparatus between the first axial position and the second axial position, and supporting the apparatus in a second orientation by grasping a second handle with the ROV. Preferably the ROV grip is shifted to the second handle before operating the actuator. Such a method may result in a controlled transition from the first orientation to the second orientation without putting excessive strain on the ROV manipulators. Preferably the first handle is axially aligned with the centre of mass and centre of buoyancy when the buoyancy material is in the first position. Preferably the second handle is at the end of the apparatus in the direction of the axial offset of the centre of buoyancy from the centre of mass with the buoyancy material in the second position. Grasping the second handle with the ROV may both aid in orientating the apparatus with the axis close to vertical but may also result in the apparatus being held in such a way that the ROV cameras have a line of sight across the top of the apparatus in order to see what is happening when positioning the apparatus on a structure such as a pipeline.

It will be appreciated that features described in relation to one aspect of the invention may be equally applicable in another aspect of the invention. For example, features described in relation to the apparatus of the invention, may be equally applicable to the method of the invention, and vice versa. Some features may not be applicable to, and may be excluded from, particular aspects of the invention.

Description of the Drawings

An embodiment of the present invention will now be described, byway of example, and not in any limitative sense, with reference to the accompanying drawings, of which:

Figure 1 is a schematic representation of a first embodiment of the invention; and

Figure 2 is a detailed view of part of the embodiment of Figure 1.

Detailed Description

In Figures 1 and 2, an apparatus 1 comprises a frame 2 and buoyancy material 3. Note that in Figure 2 a section of the buoyancy material 3 is not shown so as to reveal internal details. The apparatus 1 is a subsea scanning apparatus of a type similar to the apparatus described in GB2496736, with only the frame 2 and the components associated with the buoyancy material 3 shown in Figure 1. It will be appreciated that the pipeline scanning equipment, for example a radiation source and detector array are provided on parts mounted on the frame 2 and that further static buoyancy material may be provided, for example at the opposite end of the apparatus 1 from the movable buoyancy material 3. The apparatus has an axis A, which is aligned with the pipeline during a scan. The buoyancy material 3 is mounted on guide rods 4. Hydraulic cylinders 5 are mounted on the frame 2 and connected to the buoyancy material 3 by plates 6 bolted onto the buoyancy material 3. Springs 7 are connected to the frame 2 and the buoyancy material 3 to act as biasing means urging the buoyancy materials 3 toward the frame 2. Handles 8 are provided on the frame 2 and handles 9 are provided on the buoyancy material 3. The hydraulic cylinders 5 are operated via a valve pack having a proportional valve controllable from a remote location. In this embodiment the buoyancy material 3 is formed of separate monolithic blocks of buoyancy bound together by tie rods 10 to form buoyancy material 3.

In use the apparatus 1 is deployed through the splash zone in a basket and lifted out of the basket in a horizontal orientation (the orientation of Figures 1 and 2) by an ROV lifting the handles 8. The ROV is also connected to the apparatus 1 to provide hydraulic and electrical power. If a horizontal pipeline, or other horizontal structure, is to be scanned, the apparatus 1 is attached to the pipeline in the horizontal orientation. If a vertical pipeline, or other vertical structure, is to be scanned, the hydraulic cylinders 5 are actuated to push the buoyancy material 3 away from the frame 2 along the guide rods 4. Pushing the buoyancy material 3 in this way stretches the springs 7 but the hydraulic cylinders 5 are able to push the buoyancy material 3 against the load of the springs 7. Moving the buoyancy material 3 moves the centre of buoyancy in the same direction whilst moving the centre of mass by a lesser amount in the same direction (because the buoyancy material has a greater effect on the centre of buoyancy than the centre of mass). As a result, the centre of buoyancy, which was axially aligned with the centre of mass, becomes axially offset from the centre of mass. That causes the apparatus 1 to rotate (counter-clockwise in Figures 1 and 2) to approach a more vertical orientation. The buoyancy material 3 is moved through about 200 mm in this embodiment. Either before or after actuating the hydraulic cylinders 5, the ROV can shift its grasp from the handles 8 to the handles 9, thus supporting the apparatus 1 from nearer the top once the orientation has moved towards the vertical. Once the apparatus 1 has stabilised in its new orientation the apparatus 1 can be attached to a vertical pipeline, for example a vertical riser, and a scan carried out. For returning the apparatus 1 to the horizontal orientation the hydraulic cylinders 5 are actuated again to retract the buoyancy material 3 back to its original position by pulling on the plate 6. The buoyancy material 3 moves as a single unit because of the tie rods 10. In the event of hydraulic failure, the force exerted by the extended springs 7 will also return the buoyancy material 3 to the original position so that the apparatus 1 is once again trimmed for the horizontal orientation. Once back in the horizontal orientation the apparatus 1 can be returned to the basket for recovery to the surface or can be used again on a horizontal pipeline.

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. For example, the apparatus 1 may be trimmed by default to the vertical orientation, in which case the hydraulic cylinders 5 may start in the extended position and the springs 7 may be compressive springs that are compressed as the hydraulic cylinders 5 draw the buoyancy material 3 toward the frame 2 to change the apparatus 1 to a horizontal orientation.

Claims (14)

Claims
1. An apparatus for scanning a subsea structure, the apparatus having: an axis that aligns with an axis of the structure in use, a centre of mass, and a centre of buoyancy laterally offset from the centre of mass; wherein the apparatus comprises: a frame, buoyancy material mounted for axial movement relative to the frame, and an actuator configured to move the buoyancy material between a first axial position in which the centre of buoyancy is substantially axially aligned with the centre of mass and a second axial position in which the centre of buoyancy is axially offset from the centre of mass.
2. An apparatus according to claim 1, wherein the actuator is a remotely controlled actuator.
3. An apparatus according to claim 1 or claim 2, wherein the actuator is a hydraulic actuator.
4. An apparatus according to any preceding claim wherein the apparatus is configured such that the speed of actuation of the actuator can be controlled.
5. An apparatus according to any preceding claim wherein the actuator is configured such that the actuator can move the buoyancy material to a position between the first and second positions.
6. An apparatus according to any preceding claim wherein the apparatus comprises at least one ROV handle positioned at an end of the apparatus toward which the buoyancy material is moved when moving from the first position to the second position.
7. An apparatus according to any preceding claim wherein the apparatus includes biasing means, which urges the buoyancy material from the second position to the first position.
8. An apparatus according to any of claims 1 to 6 wherein the apparatus includes biasing means, which urges the buoyancy material from the first position to the second position.
9. An apparatus according to any preceding claim wherein the buoyancy material is mounted on guides such that the buoyancy material can be moved along the guides
10. A method of scanning a subsea structure, the method comprising: providing an apparatus at a subsea location, the apparatus having an axis, a centre of mass, and a centre of buoyancy laterally offset from the centre of mass; operating an actuator to move buoyancy material mounted on the apparatus between a first axial position in which the centre of buoyancy is substantially axially aligned with the centre of mass and a second axial position in which the centre of buoyancy is axially offset from the centre of mass; and scanning the subsea structure with the axis of the apparatus aligned with the structure.
11. A method according to claim 10, wherein the method includes the steps of scanning a first section of structure at a first orientation, operating the actuator to move the buoyancy material mounted on the apparatus between the first axial position and the second axial position, and scanning a second portion of structure at a second orientation.
12. A method according to claim 10 or claim 11, wherein the method comprises supporting the apparatus in a first orientation by grasping a first handle with an ROV, operating the actuator to move the buoyancy material mounted on the apparatus between the first axial position and the second axial position, and supporting the apparatus in a second orientation by grasping a second handle with the ROV.
13. An apparatus for scanning a subsea structure, the apparatus being substantially as described herein with reference to the accompanying figures.
14. A method of structure a subsea pipeline, the method being substantially as described herein with reference to the accompanying figures.
GB1514320.9A 2015-08-12 2015-08-12 Apparatus and method for scanning a structure Pending GB2541219A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1514320.9A GB2541219A (en) 2015-08-12 2015-08-12 Apparatus and method for scanning a structure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1514320.9A GB2541219A (en) 2015-08-12 2015-08-12 Apparatus and method for scanning a structure

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GB201514320D0 GB201514320D0 (en) 2015-09-23
GB2541219A true GB2541219A (en) 2017-02-15

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009237498A (en) * 2008-03-28 2009-10-15 Mitsui Eng & Shipbuild Co Ltd In-pipe investigation device, in-pipe investigation system, method for adjusting buoyancy and posture of in-pipe investigation device and in-pipe investigation method
CN104443318A (en) * 2014-10-29 2015-03-25 上海大学 Underwater robot balancing control movement mechanism
GB2523239A (en) * 2013-12-23 2015-08-19 Johnson Matthey Plc Scanning instrument

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009237498A (en) * 2008-03-28 2009-10-15 Mitsui Eng & Shipbuild Co Ltd In-pipe investigation device, in-pipe investigation system, method for adjusting buoyancy and posture of in-pipe investigation device and in-pipe investigation method
GB2523239A (en) * 2013-12-23 2015-08-19 Johnson Matthey Plc Scanning instrument
CN104443318A (en) * 2014-10-29 2015-03-25 上海大学 Underwater robot balancing control movement mechanism

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Publication number Publication date
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