WO2016024108A1

WO2016024108A1 - Access apparatus

Info

Publication number: WO2016024108A1
Application number: PCT/GB2015/052328
Authority: WO
Inventors: Stephen William Bedford
Original assignee: Osbit Power Limited
Priority date: 2014-08-15
Filing date: 2015-08-12
Publication date: 2016-02-18
Also published as: GB2543011B; EP3180239A1; GB201702377D0; GB2543011A; GB201414503D0

Abstract

An access apparatus (2) for enabling transfer of personnel from a seaborne vessel to a platform is disclosed. The apparatus comprises a body (6) adapted to be mounted to a deck of a seaborne vessel, a gangway (8) pivotably mounted to the body, and an engagement foot (16) mounted to the gangway and adapted to be brought into engagement with the platform. The engagement foot includes an engagement surface having a plurality of protrusions and/or recesses for engaging corresponding recesses and protrusions on the platform.

Description

ACCESS APPARATUS

The present invention relates to an access apparatus for enabling transfer of personnel and/or equipment between seaborne vessels and/or between a seaborne vessel and an offshore installation, and relates particularly, but not exclusively, to a gangway for enabling transfer of personnel to access platforms of offshore oil and gas platforms and wind turbine generators.

Gangways are used for embarkation and disembarkation when seaborne vessels are in port. Motion of the vessel relative to the harbor side is compensated by a loose connection at the vessel end of a gangway allowing the gangway to rotate about a plurality of non-parallel axes, and rollers on the harbour side which allow the end of the gangway to move.

Because of more significant wave motion, access to offshore structures is more difficult than access to a vessel when in port. In particular, more space is required for the end of the gangway to roll relative to a platform of the offshore

structure, and the constant motion makes it difficult to maintain the position of the gangway. In addition, there is often limited space on offshore installations. Furthermore, deploying the gangway and securing it in position is dangerous for cranes and personnel.

One known apparatus for addressing this problem is a hydraulically deployed gangway having a foot in the form of a cone structure for resting on a platform of the offshore installation. The foot is connected to the gangway by a gimbal connection enabling the foot to pivot about mutually

perpendicular axes relative to the gangway, and having a damping cylinder for cushioning contact loads. In this way, the foot remains static on the platform, and changes in distance between the vessel and the platform are compensated by means of a gangway of adjustable length. The cone structure is shaped so that it can be secured to the platform by means of chains.

This arrangement suffers from the disadvantage that in order to deploy the gangway, the sea conditions must be calm enough to deploy the gangway without chains, and if the sea conditions then deteriorate so that the gangway has to be removed, a mechanism for automatically releasing the chains is required, since it would otherwise be hazardous for personnel to carry out manual release of the chains. A further disadvantage of this arrangement is that the cone is generally formed from metal and can create sparks as a result of friction when it comes into contact with the platform, which is generally also of metal, thereby preventing its use in live hydrocarbon production sites .

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

According to an aspect of the present invention, there is provided an access apparatus for enabling transfer of personnel and/or equipment between seaborne vessels and/or between a seaborne vessel and an offshore installation, the apparatus comprising : - a body adapted to be mounted to a deck of a seaborne vessel ; connecting means pivotably mounted to said body; and engagement means mounted to said connecting means and adapted to be brought into engagement with a seaborne vessel and/or an offshore installation, wherein the engagement means includes an engagement surface having a plurality of protrusions and/or recesses for engaging corresponding recesses and

protrusions on said seaborne vessel and/or offshore

installation .

By providing engagement means including an engagement surface having a plurality of protrusions and/or recesses for engaging corresponding recesses and protrusions on said seaborne vessel and/or offshore installation, this provides the advantage of enabling horizontal forces to be resisted, thereby minimising movement of the engagement means relative to the seaborne vessel and/or offshore installation, without the necessity of securing the engagement means to the seaborne vessel or offshore

installation by means of chains, thereby making the apparatus safer and easier to operate.

The engagement surface may be formed from at least one resilient material.

This provides the advantage of minimising the risk of spark generation, thereby enabling the apparatus to be used in hydrocarbon producing environments.

A plurality of said recesses may comprise grooves.

A plurality of said grooves may be substantially linear and arranged such that a plurality of said grooves are not parallel to each other.

This provides the advantage of enabling more reliable engagement with protrusions on the seaborne vessel and/or offshore installation. A first plurality of said grooves may be at least partially circular, and a second plurality of said grooves may extend substantially radially of said first plurality of said grooves.

The engagement means may comprise at least one first engagement member mounted to said connecting means and pivotable about a plurality of axes not parallel to each other.

This provides the advantage of enabling the pivot axis to be mounted low in the engagement means, thereby minimising relative movement of a step-off point on a gangway relative to the seaborne vessel and/or offshore installation, and ensuring that the foot remains stable, i.e. it shears rather than tips when subjected to side loads.

The apparatus may further comprise damping means for damping movement of said engagement means relative to said body.

The connecting means may include at least one support member pivotably mounted to a main body of the connecting means for supporting said engagement means, and said damping means may include at least one damping device mounted between said main body and said support member.

The apparatus may further comprise load measuring means for measuring loads on said engagement means.

The load measuring means may be adapted to measure separate vertical and horizontal components of said loads.

According to another aspect of the present invention, there is provided an access assembly comprising an access apparatus as defined above, and at least one second engaging member adapted to be mounted to a seaborne vessel and/or offshore installation and having a plurality of recesses and/or protrusions for engaging corresponding protrusions and/or recesses on said engagement means .

A preferred embodiment of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which :-

Figure 1 is a perspective view of an access apparatus embodying the present invention;

Figure 2 is a view of a lower surface of an engagement foot of the apparatus of Figure 1 and an upper surface of a

cooperating platform grillage;

Figure 3 is a perspective view of an upper surface of the engagement foot of Figure 1 together with a gimbal connection mounted thereto;

Figure 4 is a side view of the engagement foot of Figure 3 and adjacent parts of the access apparatus in engagement with the platform grillage of Figure 2;

Figure 5 is a side view of the engagement foot of Figure 4 together with a damping apparatus prior to engagement with the platform grillage of Figure 2;

Figure 6 is a view corresponding to Figure 5 after

engagement with the platform grillage; and

Figure 7 is a perspective view of an upper surface of the engagement foot of Figure 3 with a load cell.

Referring to the Figures, an access apparatus 2 for enabling transfer of personnel from a seaborne vessel (not shown) to a platform 4 (Figure 3) of an offshore installation such as a wind turbine generator has a body 6 for mounting to a deck of the vessel, connecting means in the form of a gangway 8 having a first gangway part 10 slidably mounted within a second gangway part 12 so that the length of the gangway 8 is

adjustable, steps 14 extending from one end of the first gangway part 10, and engaging means in the form of an engagement foot 16 for engaging a platform grillage 18 (Figure 3) welded to the platform 4.

As shown in greater detail in Figure 2, the engagement foot 16 has an engagement surface 20 on its lower side, the

engagement surface 20 having a series of generally concentric circular grooves 22, together with a series of generally radially extending grooves 24. The grooves 22, 24 are sized to engage corresponding ribs 26 on the platform grillage 18, the ribs 26 being arranged in rows generally at right angles to each other. As a result of the relative directions of the grooves 22, 24 and ribs 26, engagement of the engagement foot 16 with the metal grillage 18 is reliable and provides a positive shear connection, i.e. which resists horizontal forces tending to cause relative movement between the engagement foot 16 and the platform grillage 18. The platform grillage 18 is formed of metal and the engagement surface 20 of the engagement foot 16 is formed of a resilient material such as polyurethane, in order to minimise the risk of sparks being generated when the engagement foot 16 is brought into contact with the platform grillage 18.

The engagement foot 16 is mounted to a support member 28 (Figure 5) of the gangway 8 by means of a ball and socket gimbal joint 30, enabling the gangway 8 to pivot relative to the platform 4 with the engagement foot 16 mounted thereto, and the gimbal joint 30 is located as low as is practicable on the platform grillage 18, which increases the stability of the foot 16 by minimising the extent to which lateral forces cause tipping of the foot 16 relative to the platform 4, and places the gimbal joint 30 close to the bottom step of the steps 14 of the access apparatus 2, thereby minimising translation between the steps 14 and the platform 4, making the apparatus 2 safer for users .

As is shown in Figures 5 and 6, the support member 28 is pivotably mounted via pivot 32 to a main body 34 of the first gangway part 10, and damping means in the form of a pair of damping cylinders 36 is mounted between the main body 34 and the support member 28 to reduce loads caused by landing the gangway 8 on to the platform 4. A load cell 38 provided in the gimbal joint 30 measures horizontal and vertical loads in the joint 30. Vertical loads ensure that loads applied to the platform 4 are acceptable during landing, while longitudinal loads check that the foot 16 is not approaching its stability or shear limit. A control system (not shown) monitors the load cell 38 values and provides an alarm to an operator if the expected loads are exceeded .

It will be appreciated by persons skilled in the art that the above embodiment has 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.

Claims

1. An access apparatus for enabling transfer of personnel and/or equipment between seaborne vessels and/or between a seaborne vessel and an offshore installation, the apparatus comprising : - a body adapted to be mounted to a deck of a seaborne vessel; connecting means pivotably mounted to said body; and engagement means mounted to said connecting means and adapted to be brought into engagement with a seaborne vessel and/or an offshore installation, wherein the engagement means includes an engagement surface having a plurality of protrusions and/or recesses for engaging corresponding recesses and

protrusions on said seaborne vessel and/or offshore

installation .

2. An apparatus according to claim 1, wherein the engagement surface is formed from at least one resilient material.

3. An apparatus according to claim 1 or 2, wherein a plurality of said recesses comprise grooves.

4. An apparatus according to claim 3, wherein a plurality of said grooves are substantially linear and arranged such that a plurality of said grooves are not parallel to each other.

5. An apparatus according to any one of the preceding claims, wherein a first plurality of said grooves are at least partially circular, and a second plurality of said grooves extend

substantially radially of said first plurality of said grooves.

6. An apparatus according to any one of the preceding claims, wherein the engagement means comprises at least one first engagement member mounted to said connecting means and pivotable about a plurality of axes not parallel to each other.

7. An apparatus according to any one of the preceding claims, further comprising damping means for damping movement of said engagement means relative to said body.

8. An apparatus according to claim 7, wherein the connecting means includes at least one support member pivotably mounted to a main body of the connecting means for supporting said

engagement means, and said damping means includes at least one damping device mounted between said main body and said support member .

9. An apparatus according to any one of the preceding claims, further comprising load measuring means for measuring loads on said engagement means.

10. An apparatus according to claim 9, wherein the load measuring means is adapted to measure separate vertical and horizontal components of said loads.

11. An access assembly comprising an access apparatus according to any one of the preceding claims, and at least one second engaging member adapted to be mounted to a seaborne vessel and/or offshore installation and having a plurality of recesses and/or protrusions for engaging corresponding protrusions and/or recesses on said engagement means.