GB2538221A

GB2538221A - Platform

Info

Publication number: GB2538221A
Application number: GB1503492.9A
Authority: GB
Inventors: Paterson Stuart
Original assignee: Global Energy Group Access and Coatings Ltd
Current assignee: Global Energy Group Access and Coatings Ltd
Priority date: 2015-03-02
Filing date: 2015-03-02
Publication date: 2016-11-16
Anticipated expiration: 2035-03-02
Also published as: GB2538221B; GB201503492D0

Abstract

A platform (208, Fig 2) provides access to an outer surface of an elongate member (206, Fig 2) such as oil rig legs. The platform comprises a frame which supports a walkway (222, Fig 3) and a roller 432 attached to the frame. The roller 432 has first and second outer portions 438, 440 and an inner portion 436, the diameter of the inner portion being less than the diameters of the first and second outer portions. Preferably, in use, the roller is in contact with an outer surface of the elongate member. Also, the roller may have two points of contact with the outer surface of the elongate member.

Description

PLATFORM

The present invention relates to a platform, in particular a suspended platform, for use at height against an elongate member, in particular a tubular member, more particularly a diagonal member of an oil and/or gas platform.

Offshore structures such as oil rigs or drilling platforms often operate in harsh environments. When an offshore structure is in a deployed location, safe access to the external areas of the offshore structure may be difficult to provide. In some situations, access may be required to elongate members or legs which extend from a platform of the offshore structure down into the water in which the structure is deployed. In some offshore platforms, the elongate members are tubular members and/or extend all the way to an anchor point located on a bed of the body of water in which the platform is deployed.

Typically inspections, maintenance and repairs of the area of the tubular member are achieved by lowering a suspended platform down from the platform of the offshore structure. The suspended platform may be constructed in several parts to fit around one of the tubular members, such that a level working area is provided all the way around the tubular member.

In accordance with a first aspect of the present invention there is provided a platform for providing access to an outer surface of an elongate member, the platform comprising: a frame for supporting a walkway; and a roller attached to the frame, wherein the roller has first and second outer portions and an inner portion, the diameter of the inner portion being less than the diameters of the first and second outer portions.

The platform is typically a suspended platform. The suspended platform may comprise a frame configured to provide a platform and/or walkway adjacent to the outer surface and/or at least a side of the elongate member. The roller may be provided on an inner edge of the frame and arranged to be rollable on the outer surface of the elongate member. The roller may be formed in a shape having a circular cross-section. A minimum diameter of the inner portion may be less than both the first outer diameter and the second outer diameter.

Thus, the described roller helps to stabilise the platform because the roller typically has two points of contact with the elongate member. Should the platform deviate from the stable position for any reason, this particular roller shape typically ensures that a reaction force acts to return the suspended platform to its stable position.

In some embodiments, the shape of the roller may be referred to as diabolo-shaped.

The roller may be configured to have substantially at least two points of contact with the elongate member when the roller is rolling on said elongate member. A roller with two points of contact between the roller and the elongate member causes any sideways components of force, as a result of an offset point of contact relative to the centre of the roller, to cancel with an equal and opposite sideways component of force as a result of the other point of contact. Advantageously, this prolongs the service life and durability of the roller.

A length of the roller may be less than 2 meters. The length of the roller may be less than 1.5 meters. The length of the roller may be less than 1 meter. The length of the roller may be greater than 0.3 meters. The length of the roller is typically 0.4 meters. 20 The first outer portion and the second outer portion of the roller may have a maximum diameter of greater than 100mm. The maximum diameter may be greater than 150mm. The maximum diameter may be greater than 200mm. The maximum diameter may be less than 500mm. The maximum diameter may be less than 350mm. The maximum diameter may be less than 250mm. Typically the maximum diameter is 200mm.

The inner portion of the roller may have a minimum diameter of greater than 10mm. The minimum diameter may be greater than 50mm. The minimum diameter may be greater than 100mm. The minimum diameter may be less than 300mm. The minimum diameter may be less than 200mm. The minimum diameter may be less than 150mm. Typically the minimum diameter is 138mm.

The inner portion of the roller may be an axle of the roller. Thus, two separate outer portions of the roller may be provided.

The first outer portion and the second outer portion may both be outermost portions of the roller. Thus, the outermost portions of the roller may be considered to be the first outer potion and the second outer portion of the roller.

The first outer portion may be at a first end of the roller, the second outer portion may be at a second end of the roller, and the inner portion may be positioned substantially centrally between the first outer portion and the second outer portion.

The roller may taper continuously inwardly from the first outer portion to the inner portion. The roller may taper continuously inwardly from the second outer portion to the inner portion.

The roller may be formed from a rubber material. The rubber material may comprise neoprene. Neoprene has been found to be particularly suitable due to its elastic flexibility and durability. The rubber material may only cover the roller on the parts where the roller is contactable with the elongate member.

A proportion of the weight of the platform may be transferred to the elongate member through the roller.

The roller may be provided on an inner perimeter of the support frame. The roller may be provided on the second portion of the frame.

The frame may be configured to substantially surround a cross-section of the elongate 25 member.

The support frame may be configured to have a substantially rectangular shape. The width of the support frame may be greater than 2 meters. The width of the support frame may be less than 10 meters. The length of the support frame may be greater than 2 meters. The length of the support frame may be less than 10 meters.

The frame may comprise a first portion and a second portion. For fitting the platform around the elongate member, the second portion may be configured to be temporarily moved or removed to allow the elongate member to be inserted within an opening defined by the frame. Thus, the frame can be easily manoeuvred into position around an elongate member, and then held in place by closing the frame around the cross-section of the elongate member, so that the frame surrounds the cross-section.

In some embodiments, the frame may comprise three or four or more portions. Thus, each portion of the frame can be easily manoeuvred into position on an elongate member, and then held in place by assembling the portions of the frame around the cross-section of the elongate member to form the frame surrounding the cross-section.

The roller may be configured to have substantially exactly two points of contact with the elongate member when the roller is rolling on said elongate member. The roller may be arranged such that two of the at least two points of contact straddle a centreline formed by the uppermost points of a plurality of perpendicular cross-sections through the elongate member.

The roller may be the only roller attached to the platform. In some embodiments, additional rollers may be provided on the same side of the frame, and configured to roll on the same side of the elongate member. In some embodiments, additional rollers provided on the frame and configured to roll on the elongate member may be flat rollers.

The platform may be configured for use beneath a platform of an offshore platform.

The platform may be for providing a raised platform, in particular beneath a platform of an offshore structure situated in a body of water, the offshore structure comprising at least one elongated member which extends diagonally beneath the platform of the offshore structure towards a surface of the body of water.

The platform may further comprise at least one winch configured to raise or lower the platform relative to the platform of the offshore structure. The platform typically comprises at least four winches. The at least on winch of the may be configured to engage with at least one cable or rope wherein one end of the cable or rope is secured above the elongate member and/or above the platform. The at least one winch may be controlled from a winch controller located locally on the platform.

The at least one winch is typically pivotably connected to the platform. The at least one winch may be pivotably connected to the platform by a pivotal connection on the platform. Typically in use, the at least one winch is in-line with the at least one cable or rope when one end of the cable or rope is secured above the elongate member and/or above the platform. In use, the at least one winch and at least one cable or rope are typically parallel or at least substantially parallel to the at least one elongate member extending diagonally beneath the platform.

It may be an advantage of the present invention that the at least one winch is pivotably connected to the platform, such that the at least one cable or rope enters the winch at an appropriate angle so that the at least one winch can function properly and/or safely.

The platform may further comprise at least one sky lock configured to hold the platform in position relative to the platform of the offshore structure. The platform may comprise at least four sky locks. Each sky lock may be configured to selectively engage with at least one cable or rope wherein one end of the cable or rope is secured above the suspended platform.

The walkway may comprise floorboards and/or grating.

Although embodiments of the present invention have referred to a platform, it will be appreciated that the term cradle may also be used. Similarly, although embodiments of the invention have referred to elongate members, it will be appreciated that any of the features can also be applied to tubular members.

An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is an illustration of an embodiment of an aspect of an offshore platform incorporating two different platforms each in accordance with the present invention; Figure 2 is an illustration of one of the platforms shown in Figure 1.

Figure 3 is an illustration of the other of the platforms shown in Figure 1.

Figure 4 is an illustration of a roller; Figure 5 is an illustration of a roller according to one embodiment of the present invention; Figure 6 is an illustration of the operation of a platform according to one embodiment of the present invention; and Figure 7 is an illustration of the operation of an alternative platform according to one embodiment of the present invention.

The present disclosure provides a suspended platform for use around a tubular support member of an offshore structure. A frame or support frame of the suspended platform substantially surrounds the tubular support member to prevent the platform being displaced away from the tubular support member, and a roller is attached to one side of the support frame to roll along an upper surface of the tubular support member.

Significantly, the roller is designed to have two points of contact with the tubular support member.

In use, the suspended platform can be used to provide an elevated platform for completing inspection, maintenance or repair work on a tubular support member. The suspended platform can be raised or lowered through the use of, for example, winches attached to cables. The roller ensures the suspended platform always moves smoothly over the surface of the tubular support member.

A cradle having a roller with at least two points of contact with the tubular support member, as described in the present disclosure, improves stability of the cradle compared to cradles using a single, flat roller and also reduces the loading on any single point on the roller. Additionally, a roller with two points of contact means that any sideways components of force as a result of an offset point of contact relative to the centre of the roller may cancel with an equal and opposite sideways component of force as a result of the other point of contact. Advantageously, this prolongs the service life and durability of the roller.

Figure 1 shows an illustration of an embodiment of an offshore platform 100 in accordance with the present invention. The offshore platform 100 comprises a platform level 102 typically located above a water level of the offshore platform 100. The platform level 102 is supported on diagonal members 104, 106 which extend from the platform level 102 into the water in which the offshore platform 100 is deployed. In the presently described embodiment, a first diagonal member 104 extends at an angle of 18 degrees to the vertical. A second diagonal member 106 extends at an angle of 36 degrees to the vertical. Typically, the first diagonal member 104 will have a smaller cross section than the second diagonal member 106. The diagonal members 104, 106 typically have a substantially constant cross section along a length of the diagonal member 104, 106. A diameter of the first diagonal member 104 is 1219mm, and a diameter of the second diagonal member 106 is 1524mm. A first suspended platform 110 is provided around the first diagonal member 104 and a second suspended platform 108 is provided around the second diagonal member 106. In the presently described embodiment, the first suspended platform 110 and the second suspended platform 108 are each specifically configured for use around the first diagonal member 104 and the second diagonal member 106 respectively.

Figure 2 shows an illustration of the second suspended platform shown in Figure 1.

Both a first diagonal member 204 and a second diagonal member 206 are shown extending from an area on an underside of a platform level 202 provided as part of an offshore platform 200. The second suspended platform 208 is provided around the second diagonal member 206. The second suspended platform 208 comprises a floor section/walkway 212 forming a working surface on which equipment, spare parts, tools or persons may be supported. Railings 213 extend upwards from an edge of the second suspended platform 208 and are configured to provide a supporting structure, to which encapsulation material can be attached if required. The encapsulation material is used to prevent any environmental contamination due to the treatments or maintenance being applied to the diagonal members. The railings 213 also prevent persons or other large items falling off the floor section 212 of the second suspended platform 208. A length of the second suspended platform 208 is 5195mm. A first winch pair 214 and a second winch pair 216 are provided on the second suspended platform 208 for connecting the second suspended platform 208 to the platform level 202 using hoist rope pairs 218 configured to secure to the platform level at anchor points 220. As will be described further with reference to Figure 6, winches 214, 216 and the hoist rope 218 are used to raise or lower the second suspended platform 208 into position on the second diagonal member 206.

Figure 3 is an illustration of the first suspended platform shown in Figure 1. A first diagonal member 204 and a second diagonal member 206 are shown extending from an area on an underside of a platform level 202 provided as part of an offshore platform 200. A first suspended platform 210 is provided around the first diagonal member 204. The first suspended platform 210 comprises a floor section/walkway 222 forming a working surface on which equipment, spare parts, tools or persons may be supported. Railings 223 extend upwards from an edge of the first suspended platform 210 and are configured to provide a supporting structure, to which encapsulation material can be attached if required. The encapsulation material is used to prevent any environmental contamination due to the treatments or maintenance being applied to the diagonal members. The railings 213 also prevent persons or other large items falling off the floor section 222 of the first suspended platform 210. A length of the first suspended platform 210 is 4280mm. A first winch pair 224 and a second winch pair 226 are provided on the first suspended platform 210 for connecting the first suspended platform 210 to the platform level 202 using hoist ropes 228 configured to secure to the platform level at anchor points 230. As will be described further with reference to Figure 6, winches 224, 226 and the hoist rope 228 are used to raise and lower the first suspended platform 210 into position on the first diagonal member 204.

Figure 4 shows a roller for use on a suspended platform. The roller assembly 432 is secured to a side-board 442 provided on a lower portion of the safety railing 423. In this particular embodiment, the roller assembly 432 is provided on an inner edge of the suspended platform such that a roller of the roller assembly 432 is arranged to engage with an upper surface of the diagonal member. The roller of the roller assembly 432 comprises a first outer portion 438 having a first diameter, a second outer portion 440 located on the opposite end of the roller and having substantially the same diameter, and an inner portion 436 provided between the first outer portion 438 and the second outer portion 440. The width of the roller is 400 millimetres. The central portion has a central diameter less than the first or second diameters, and the roller tapers inwardly from both the first outer portion 438 to the central portion 436 and from the second outer portion 440 to the central portion 436. The roller rotates about a fixed axle 434.

This roller design ensures that there are two points of contact between the roller and the diagonal member. The contact surface of the roller is formed from a rubber material. Specifically, the rubber material is a material containing neoprene.

Figure 5 shows the roller assembly 532 mounted to a side of a first suspended platform 510, the first suspended platform 510 having a floor section 522. The floor section 522 is formed from a series of floor boards provided adjacent each other to form a substantially continuous floor on a base of the first suspended platform 510. The roller assembly 532 is provided at substantially the same height as the floor section 522.

Figure 6 shows the second suspended platform 608 configured for operation around a diagonal member 606. A width of the second suspended platform 608 is 3985mm. The second suspended platform 608 comprises a floor section 612. In configuration A, shown on the left of Figure 6, a section of the second suspended platform 608 has been temporarily removed to allow the second suspended platform 608 to be raised into a position substantially surrounding the diagonal member 606. Four hoist ropes 618 are used to raise or lower the second suspended platform 608 vertically. The four hoist ropes 618 attach to a first winch pair 614 and a second winch pair 616. The first winch pair 614 and second winch pair 616 each comprise two separate winches, such that a single winch is positioned at each corner of the rectangular inner perimeter of the suspended platform 608 and a hoist rope 618 is attached to each winch. Four sky lock wires (not shown) are also attached to four sky locks (not shown), which are positioned substantially alongside each of the winches 614, 616. In a rigging position, the four hoist ropes 618 and the four sky lock wires are both anchored above the second suspended platform 608. When the second suspended platform 608 is raised into position around the diagonal member 606 using the winches 614, 616 and the hoist ropes 618, the second suspended platform 608 can be temporarily secured in its vertical position using the sky locks. When engaged, the sky locks hold the second suspended platform 608 in position on the sky lock wires by friction. The hoist rope 618 can then be transferred from the rigging position directly above the suspended platform to an operating position at the top of the diagonal member 606. In this way, the hoist ropes 618 now run parallel with the diagonal member 606. At the same time, the removable suspended platform section 648 is positioned in the gap in the second suspended platform 608 which allowed the suspended platform to be raised into position around the diagonal member 606. When these changes have been completed, the second suspended platform 608 is provided in configuration B as shown on the right of Figure 6. The roller assembly is not shown in Figure 6, though it will be appreciated from the description with reference to Figures 4 and 5 that, in the presently described embodiment, the roller assembly would be located on the removable suspended platform section 648. Typically, the roller assembly is only installed in position after the second suspended platform 608 is fully assembled around the diagonal member 606. The first winch pair 614 and second winch pair 616 can be used to move the second suspended platform 608 to a range of positions throughout a length of the diagonal member 606, and specifically where the range of positions are all above the surface of the water in which the offshore platform is deployed. All four winches are operated together to keep the second suspended platform 608 level. The first winch 614 and second winch 616 may each be provided on pivoting fixings to allow the hoist ropes 618 to move from the rigging positions to the operating positions.

The second suspended platform 608 may be provided in the position described with relation to configuration A by raising the second suspended platform 608 from a barge located beneath the platform level of the offshore platform. The four hoist ropes 618 and four sky lock wires are lowered to the surface of the barge and attached to the second suspended platform 608. Although the first winch pairs 614 and second winch pairs 616 are each positioned on the second suspended platform 608, it would be possible for the first winch 614 and second winch 616 to be provided elsewhere on the offshore platform, such as on the platform level of the offshore platform.

Controlling the winches to raise and lower the second suspended platform 608 on the hoist ropes 618 is performed from a control panel (not shown) located locally on the suspended platform.

Figure 7 shows the first suspended platform and is substantially the same as Figure 6, but with the hereinafter described differences. Figure 7 relates to the first suspended platform 710 provided around the first diagonal member 704. As will be appreciated from the orientation of the diagonal member 704 as shown in the bottom images of Figure 7, the removable section 754 is located on an opposite edge of the first suspended platform 710 to the removable section 648 in Figure 6. A width of the first suspended platform 710 is 3395mm. For the avoidance of doubt, the roller assembly, also not shown in Figure 7, would be provided on the inner-facing side of the removable section 754 such that the roller would engage with a surface of the first diagonal member 704 having an outward normal pointing above the horizon.

In some embodiments, the hoist lines 218, 228, 618, 728 may each be anchored at a fixed location on a region of the platform level above each respective diagonal member. In other embodiments, a movable anchor point may be provided on, for example, a crane, to provide the hoist lines 218, 228, 618, 728 in a variety of positions on or above the platform level of the offshore platform as required. In some embodiments, the movable anchor point may be used for a rigging situation when the platform is manoeuvred into position around the diagonal member. During operation, a fixed anchor point may be used.

Although the presently described embodiments of the suspended platform feature four winch mechanisms and one roller assembly, it will be appreciated that alternative suspended platforms may feature more winch mechanisms in combination with more rollers, though at least one of the rollers should be positioned to engage with a surface of the diagonal member having an outward normal pointing above the horizon and have at least two points of contact between the roller and the diagonal member.

Furthermore, although the presently described embodiments describe that the winch mechanisms operate together, it will be appreciated that the winches may operate in independent groups where those groups are connected to separate portions of the suspended platform during rigging and assembly of the suspended platform.

Although the presently described embodiments of the roller describe a shape having a constant taper from the edge portion to the central portion, it will be appreciated that alternative shapes may be possible. A middle portion of the roller must have a minimum diameter smaller than a maximum diameter of the roller on each side of the middle portion. Furthermore, the roller must be arranged such that each of the two sides of the roller adjacent to the middle portion of the roller will be in contact with the member on which the roller is configured to roll. In this way, a roller is provided which allows a working surface to be raised and lowered stably along the length of an elongated member such as a diagonal member.

Although the figures may depict suspended platforms or tubular support members having given measurements or proportions, it will be appreciated that suspended platforms and tubular support members having other measurements and proportions can be provided without departing from the scope of the present disclosure.

Modifications and improvements can be incorporated herein without departing from the scope of the present invention.

Claims

CLAIMS1. A platform for providing access to an outer surface of an elongate member, the platform comprising: a frame for supporting a walkway; and a roller attached to the frame, wherein the roller has first and second outer portions and an inner portion, the diameter of the inner portion being less than the diameters of the first and second outer portions.
2. A platform as claimed in claim 1, wherein in use the roller is contactable with the outer surface of the elongate member.
3. A platform as claimed in claim 1 or claim 2, wherein in use the roller has two points of contact with the outer surface of the elongate member.
4. A platform as claimed in any preceding claim, wherein the first and second outer portions are both outermost portions of the roller.
5. A platform as claimed in any preceding claim, wherein the inner portion is substantially centrally positioned between the first and second outer portions.
6. A platform as claimed in any preceding claim, wherein the roller tapers continuously inwardly from the first and second outer portions towards the inner 25 portion.
7. A platform as claimed in any preceding claim, wherein the first and second outer portions of the roller have a diameter of equal to or greater than 200mm.
8. A platform as claimed in any preceding claim, wherein the inner portion of the roller has a diameter of equal to or less than 150mm.
9. A platform as claimed in any preceding claim, wherein the roller comprises neoprene.
10. A platform as claimed in any preceding claim, wherein in use a proportion of the weight of the platform is transferred to the elongate member through the roller.
11. A platform as claimed in any preceding claim, wherein in use the frame is configured to substantially surround the elongate member.
12. A platform as claimed in any preceding claim, wherein in use the roller is attached to a part of the frame closest to the outer surface of the elongate member.
13. A platform as claimed in any preceding claim, wherein at least one winch is pivotably connected to the platform.
14. A platform according to claim 13, wherein in use the at least one winch is in-line with at least one cable, one end of the cable secured above the platform.
15. A platform according to claim 14, wherein in use the at least one winch and at least one cable are at least substantially parallel to the elongate member.