GB2136037A - Method and apparatus for transferring personnel to and from an offshore platform - Google Patents

Abstract

An offshore platform is provided having a safety landing platform (14) for transferring personnel to and from the platform. The safety landing platform is located away from and below the drill or production deck so as to provide a non-congested area in which a crane operator may deposit a personnel basket. <IMAGE>

Description

SPECIFICATION Method and apparatus for transferring personnel to and from an offshore platform This invention relates to the transferring of personnel to and from an offshore platform where a drill or production deck is very high above the water and is cluttered with production equipment and, in particular, to a safety landing platform on which personnel may be landed.

A commonly used method of transferring personnel in offshore platform operations involves the platform cargo crane and a personnel basket, known as the "Billy Pugh". Personnel hold on to and straddle an open net personnel basket while being hoisted between a drill or production deck and a workboat. The drill or production deck is usually 100 to 120 feet (30--36 m) above the water. Crane accidents occurring during transfer operations are a serious concern since they cause serious injuries to the personnel being transferred and sometimes even death. Many factors, such as faulty maintenance, worn out parts, improper operations and operator error, contribute to cause these accidents.While close attention to these factors will help to minimize these accidents, it is desirable to provide surroundings which of themselves would help to minimize the chances of such accidents to happen.

This invention provides proper surroundings for the transfer of personnel to and from an offshore platform by providing a safety landing platform secured to the offshore platform structure at a location high enough to provide proper clearance for workboats or crew ships, but low enough so that possible injury from a fall from such a height would be minimized. To obtain these characteristics, the bottom of the safety landing platform should be about twenty-five feet (7.5 m) from the normal location of the ocean surface at high tide. Also, the surface, on which personnel are to be landed, is located a considerable distance from the offshore platform structure so as to be in clear view of the crane operator. The workboat must not be under the safety landing platform when personnel are being transferred to or from the safety landing platform.

The invention will be further described with reference to the accompanying drawings illustrating preferred embodiments of platforms constructed in accordance with the concept of this invention.

Figure 1 is a schematic illustration of a side elevation of an offshore platform equipped with two safety landing platforms; Figure 2 is a top plan view of a safety landing platform; Figure 3 is a side elevation of a safety landing platform; Figure 4 is a cross section taken along the lines 4--4 of Figure 2; Figure 5 is a side elevation of a modified safety landing platform; and Figure 6 is a top plan view of the landing deck.

Referring to the drawings and in particular to Figure 1, there is illustrated an offshore platform 2 having a drill or production deck 4 supported by a plurality of legs 6 which are suitably secured in the ocean bed. An oil rig 8 is located on the drill or production deck 4 as are two cranes 10. The drill or production deck 4 is normally located a distance of from about 1 00 to about 120 feet (30--36 m) above the ocean surface 12. In Figure 1 , there are two safety landing platforms 14, but it is understood that in many locations only one safety landing platform is necessary. As illustrated in Figure 1, a basket 16 is used to transfer personnel 1 8 between the safety landing platform 14 and the workboat 20.The workboat 20 must never be directly under the safety landing platform 14 during transfer of personnel.

In Figures 2, 3, and 4, there is illustrated an embodiment of the invention wherein the main support for the platform is a cantilevered truss member 22 which is securely mounted at one end 24 to one of the legs 6. Although the safety landing platform is illustrated as being mounted to the leg 6, it is to be understood that the type of mounting may be varied to suit the particular offshore platform to which it is to be mounted.

Stairwells 25 are available at the one end of the safetly landing platform so that personnel landed thereon may proceed to their quarters and the drill or production deck. At the other end of the cantilevered truss member 22, there is a landing deck 26 on which the basket 1 6 carrying the personnel 1 8 may be deposited. The landing deck 26 is supported by suitable means such as the gusset support 28. Although the landing deck is illustrated as being circular, it may, of course, be of other geometrical configurations.

A walkway 30 extending from the landing deck 26 to the exit end 32 of the safety landing platform 1 4 is mounted on the upper surface of the cantilevered truss member 22 by suitable supporting structure secured at spaced intervals to the cantilevered truss member 22 and the walkway as described more fully below. Handrails 36 are provided around the outer periphery of the landing deck 26 and on each side of the walkway 30.

The cantilevered truss member 22 comprises support blocks 38 which are secured to the iegs 6 by suitable means such as bolts (not shown) passing through openings 40. Securely attached to each block 38 are four square tubings 42 each of which fits into an opening 43 in the support block 38. Each of the square tubings 42 is welded to the support block 38 around the periphery of each opening 43 on both sides of the support block 38.

At its other end 44, each tubing 42 is connected to the gusset support 28. As illustrated in Figure 3, because of this the upper square tubing 42 has a length slightly greater than the lower square tubing 42. The end portions of the upper tubing 42 assist in supporting the landing deck 26. The square tubing 42 are cross braced to a plurality of T shaped supports 46, 48, 50 and 52. The T shaped support 50 is notched at 54 and 56 to the dimension of the square tubing. The T shaped support 52 is flush with the upper surface of the square tubing 42 so that the grating forming the walkway 30 amy be mounted thereon. The T shaped supports 46 and 48 extend vertically above the walkway 30 to provide supports for the handrails 36. Additional bracing 58 and 60 are provided between the T shaped supports 50 and 52.All connections between the square tubings 42, and T shaped supports 46, 48, 50 and 52, the walkway 30, the handrails 36 and the additional bracing 58 and 60 are preferably by welding.

The gussett support 20 comprises a plurality of angle steel supports 62 connected, preferably by welding, to the underside of the landing deck 26. A plurality of T shaped supports 64, connected, preferably by welding, to the landing deck 26 and the angle steel supports 62 extend vertically above the landing deck 26 to provide supports for the handrail 36. As illustrated in Figure 3, the T shaped supports 64 extend vertically at an angle to provide more room for personnel to step to and from the personnel basket.

In Figure 5, there is illustrated another embodiment of the invention wherein the support blocks 38 are secured to support means 66 rotatably secured to the leg 6 by pivot means 68.

Means, such as a cable 70, are secured to the cantilevered truss member 22 and to suitable means (not shown) in the leg 6 so that the safety landing platform may be raised into a position against the bulkhead when desirable, such as during severe weather conditions.

As illustrated in Figure 6, the surface of the landing may be divided into concentric circular areas and painted in contrasting colours to assist the crane operation in spotting the personnel basket. The safety landing platform 1 4 is secured to the leg 6 so that the landing deck 26 is about 25 feet (7.5. m) from the ocean surface 12. While the actual distance of the landing deck 26 above the ocean surface 12 may be varied, it should be such a distance that in the event of an accident, personnel falling from the deck 26 will not be seriously injured. The landing deck 26 must be located a sufficient distance from the leg 6 so that the crane 10 operator will have a clear view of the landing deck 26. In most instances, a distance of 25 feet (7.5 m) from the leg 6 to the outermost point of the landing deck 26 is sufficient.The landing deck 26 should have an approximate diameter one and a half (12) times the largest diameter of the basket 1 6.

In one embodiment of the invention all the components comprise steel of the type SAE 1045 or equivalent and are painted to withstand the effects of salt water corrosion. The cantilevered truss member 22 comprises square tubing 4" x 4" x 2tt (10 X 1.27cam); each support block 38 is a square plate 1' x 1' x 1" (30 x 30 x 2.54 cms) with a central opening to receive one end of the square tubing 42 and four 1" (2.54 cms) circular openings adjacent each corner through which bolts may pass to secure the cantilevered truss member to the leg 6. The T shaped supports 46, 48, 50 and 52 are 3" x 3" x 2tt (7.6 x 7.6 x 1.27 cms); the additional bracing 58 and 60 are 2" x (5 x 1.27 cms) flat stock; the handrail 36 is also 2" x 2tt (5 x 1.27cms) flat stock.The gusset supports 62 are angle steel 3" x 3" x +" (7.6 x 7.6 x 1,27 cms) which is field cut to size. The T shaped handrails supports are 3" x 3" x 2n (7.6 x 7.6 x 1.27 cms) with the top end of the ones around the landing deck 26 being offset a distance of 5 inches (13 cms) as illustrated in Figure 3. The landing deck 26 is 10 foot (3 m) in diameter and comprises a" (1.9 cm) thick steel plate. The walkway 30 comprises -" (1.9 cm) catwalk grating and is 36 inches (0.9 m) in width. A safety landing platform constructed as above will support a load of about 8000 pounds (3629 kg) with a safety factor of 4. Thus, the normal transfer of personnel to and from a workboat and the offshore platform can be readily accommodated.

While the preferred embodiments of the invention have been described herein, the invention may be otherwise embodied and practised within the scope of the following claims.

Claims (18)

1. A method of transferring personnel to and from an offshore platform having a drill or production deck at a predetermined distance above the ocean surface, which comprises lifting the personnel in a personnel basket carrier onto or off a personnel landing platform mounted on said offshore platform to one side thereof and located a second predetermined distance above the ocean surface but below the level of the drill or production deck.

2. A method according to claim 1, wherein said landing platform is closer to the ocean surface than it is to said drill or production deck.

3. A method according to claim 1 or 2, wherein said second predetermined distance is about twenty-five feet (7.5 m).

4. A method according to claim 1, 2, or 3, wherein the personnel basket is lowered onto or lifted off the landing platform by a crane whose operator is located at a position having a clear view of the landing platform or at least that part onto which the said personnel are to land.

5. A method according to any one of claims 1-4, wherein, when not in use, said landing platform is pivoted to an inoperative position contiguous to said platform.

6. An offshore platform having a drill or production deck located a predetermined distance above the ocean surface wherein there is provided to one side thereof and below the level of the drill or production platform or personnel landing platform onto or from which personnel can be transferred by means of a crane-operated personnel basket.

7. An offshore platform according to claim 6, wherein said landing platform is located closer to said ocean surface than it is to said drill or production deck.

8. An offshore platform according to claim 6 or 7, wherein said landing platform is a distance of about twenty-five feet above said ocean surface (7.5 m).

9. An offshore platform according to claim 6, 7, or 8 comprising a crane positioned thereon so that the operator has a clear view of the landing platform, or at least that part thereof on which the personnel are to land in said basket.

10. An offshore platform according to any one of claims 6-9, wherein said landing platform is pivotally connected to the offshore platform and pivotable thereon from a substantially horizontal operative position to a substantially vertical inoperative position contiguous to said platform.

11. An offshore platform according to any one of claims 6-10 wherein said landing platform comprises a cantilevered truss member projecting from the side of the offshore platform and supporting on its upper side a landing deck of the personnel basket.

12. An offshore platform according to claim 11 wherein said cantilevered truss member comprises a plurality of support members extending substantially horizontally from said offshore platform and a plurality of bracing members connected to said support members at a plurality of spaced locations therealong.

13. An offshore platform according to claim 12, further comprising a gusset support connected to the distal ends of said plurality of support members for supporting said landing deck.

14. An offshore platform according to claim 11, 12 or 13, further comprising a walkway extending from said landing deck to said offshore platform.

1 5. An offshore platform according to claim 14, further comprising a handrail adjacent the edges of said landing deck and said walkway.

1 6. An offshore platform according to any one of claims 11-1 5, wherein said landing deck has a circular configuration.

17. An offshore platform according to claim 1 6 further comprising a handrail adajcent the edge of said landing deck and having an inner diameter greater than the outer diameter of said landing deck.

18. An offshore platform according to any one of claims 11-17 further comprising means on said landing deck to assist in properly positioning the personnel basket on said landing deck.