GB2106074A - Workplatform - Google Patents

Abstract

A workplatform (10) for providing access beneath deck level (30) has a support structure comprising a first arm (16) capable of rotation by motor (18) about a vertical axis and is suspended at an adjustable height (60) beneath the deck level (30) with a second arm (14) pivotably mounted on the end of the first arm (16) and supporting the workplatform (10). As shown the first arm (16) is formed of several telescopic sections and is secured to the lower end of a telescopic support column (19) which is rotatable by allowing ring and motor (24) about a vertical axis. The first arm (16) can be pivotably secured to the support column (19) and if the workplatform (10) is to be stored above deck level (30), then a retraction mechanism (40) is provided. The workplatform (10) has the degrees of freedom illustrated by the phantom lines and by the arrows designated 20, 52, 60, 62 and 64. <IMAGE>

Description

SPECIFICATION Workplatform The present invention relates to a workplatform for providing access beneath deck level. Such a workplatform is suitable for inspection, repair and maintenance operations on fixed production platforms offshore and semi-submersible vessels.

Onshore, the workplatform may be used in storage tanks, silo plants, shipyards etc.

Hitherto, when requiring access beneath the level of a deck, it was usual to erect scaffolding which in the case of an offshore drilling well would be suspended from the platform or deck. A problem encountered in such circumstances is that if a storm should occur at short notice, the scaffolding cannot be dismantled and, left at the mercy of the storm, can suffer severe and expensive damage.

According to the present invention, in order to provide access beneath the level of a deck, there is provided a workplatform having a support structure comprising an arm capable of rotation about a vertical axis and suspended at an adjustable height beneath deck level and a second arm pivotably mounted on the end of the first arm and supporting the workplatform.

In the process of maintenance of an oil drilling rig, it is not sufficient to provide a workplatform on the end of an arm which can rotate through 360" since in some positions rotation of the arm will be impeded by obstructions such as the support columns. In those circumstances, there would be numerous blind spots which cannot be reached by the workplatform. The invention therefore provides a horizontally articulated support structure for the workplatform enabling the workplatform to reach around obstructions.

Preferably, the rotatable arm is secured to the lower end of a telescopically collapsible support column rotatable about a vertical axis.

Conveniently, the first of the horizontally rotatable arms is formed of several telescopically collapsed sections to permit accurate positioning of the platform over an extended radius centered on the vertical column.

Advantageously, all the telescopically collapsed sections and the motor for articulating the second arm about the first are hydraulically operated with manual back-up to allow movement of the workplatform in the event of hydraulic failure.

The vertical column may be suspended beneath deck level, for example on a trolley guided on rails secured beneath the deck level. It is alternatively possible for the platform to be stored above deck level. In the latter case, the vertical column may be mounted on a retraction mechanism for permitting the column together with the support arm to be raised above deck level. The retraction mechanism may conveniently comprise a hinged quadrilateral structure having two short arms and two long arms, one of the short arms being secured to the deck and the other serving to support the vertical column.

The retraction mechanism is hydraulically operated and if desired may also be mounted on a trolley for movement on rails above deck level. To assist in storage and to improve the numbers of degrees of freedom of movement of the workplatform, it is preferable that the horizontally rotatable arm should be mounted on the lower end of the vertical column in such a manner as additionally to be pivotable in a vertical plane.

The invention will now be described further, by way of exampie, with reference to the accompanying drawing which is a perspective view of a hydraulically operated workplatform in accordance with the present invention.

The workplatform in Figure 1 consist of a basket 10 suspended under gravity from one end 12 of an arm 14 articulated to the end of a second, telescopically collapsible arm 16. A hydraulic motor serves to rotate the arm 14 relative to the arm 16.

The arm 16 is itself pivotably mounted on the lower end of a telescopically collapsible column 18 and is pivotable relative to the column 18 in a vertical plane as indicated by an arrow 20 under the action of hydraulic jacks 22.

The column 19 is in turn supported within a slewing ring and motor 24 which enables the column 19 together with both the arms 14 and 16 to rotate about a vertical axis.

The structure so far described may be suspended on rails from the lower surface of a deck to provide access but the embodiment described, for ease of storage, is mounted above the deck, generally designated 30 and can be raised above deck level by means of a retraction or luffing mechanism generally designated 40.

The luffing mechanism 40 consists of a quadrila teral pivoted structure having two longer sides 42 and 44 and two shorter sides 46 and 48. The slewing motor 24 is connected to the short sides 48 and hydraulic luffing cylinders 50 are connected to pivot this quardrilateral structure in a vertical plane in the direction of the arrow designated 52.

in use, the platform 10 always remains vertical by virtue of its suspension and personnel can be accommodated within the basket with safety. The movement of the basket 10 has several degrees of freedom. Firstly, for height adjustment, the telescopically collapsible column 19 can be extended and retracted as represented by the arrows 60 and the arm 16 can be pivoted in a vertical plane as represented by the arrow 20. For horizontal positioning, the arms 14 and 16 can be moved together under the action of the slewing motor 24 and the arm 14 may be articulated about the end of the arm 16 under the action of the motor 18. Additionally, the arm 16 being telescopically collapsible permits radial movement of the basket 10 with respect to the column 19 as represented by the arrows 52.

For storage, first the arm 14 is articulated by the motor 18 to move in the direction represented by the arrows 64 so as to lie parallel to the arm 16. The arm 16 is telescopically collapsed and hinged to adopt a vertical position. The column 19 is then rotated to allow the basket 10 to clear the deck 30 and the column 19 is telescopically collapsed to raise the basket and the arms 14 and 16 to just below deck level. Finally, the luffing cylinders are retracted to pivot the retraction mechanism in the direction of the arrow 52. During this movement the column 19 is both raised and slightly tilted counter-clockwise as viewed to allow it to clear the edge of the deck with greater clearance.

All the hydraulic mechanisms are provided with a mechanical back-up for safety in the event of failure.

It is envisaged that hollow hydraulic cylinders be used with a rope passing centrally down the column 19 and around a winch 70. In the event of hydraulic failure, the valves of the hydraulic system may be opened and the workplatform winched mechanically to safety.

Though the shorter arm of the retraction mechanism is shown secured to the deck 30, it may alternatively be on rails to permit positioning of the work platform wherever desired on the deck. In such an instance, anchoring means may additionally be provided to prevent movement of the wheeled trolley supporting the work platform while the platform is in use.

CLAIMS (Filed on 15 April 1982) 1. A workplatform having a support structure comprising a first arm capable of rotation about a vertical axis and suspended at an adjustable height beneath deck level and a second arm pivotably mounted on the end of the first arm and supporting the workplatform.

2. A workplatform as claimed in claim 1, wherein the first arm is secured to the lower end of a telescopically collapsible column which is rotatable about a vertical axis.

3. Aworkplatform as claimed in claim 2, wherein the first arm is secured to the support column in a manner so as to be pivotable in a vertical plane.

4. A workplatform as claimed in any preceding claim, wherein the first arm is formed of several telescopically collapsed sections to permit accurate positioning of the platform over an extended radius centered on the said vertical axis.

5. A workplatform as claimed in claim 4, wherein a motor is provided for articulating the second arm about the first arm and the motor and the telescopic components are hydraulically operated.

6. A workplatform as claimed in claim 5, wherein a manual operating system is provided so as to allow movement of workplatform in the event of a hydraulic failure.

7. A workplatform as claimed in any preceding claim and claim 2, wherein the support column is suspended beneath deck level.

8. A workplatform as claimed in claim 7, wherein the support column is suspended from a trolley which is guided on rails secured beneath deck level.

9. A workplatform as claimed in any of claims 1 to 6 and claim 2, wherein the support column is mounted on a retraction mechanism for permitting the column together with the first and second arms to be raised above deck level.

10. A workplatform as claimed in claim 9, wherein the retraction mechanism comprises a quadrilateral pivoted structure having two short arms and two long arms, one of the short arms being secured above deck level and the other serving to support the support column.

11. A workplatform as claimed in claim 10, wherein the retraction mechanism is hydraulically operated.

12. Aworkplatform as claimed in claim 10 or 11, wherein the short arm secured above deck level is secured to a trolley for movement on rails secured above deck level.

13. A workplatform substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. pivot the retraction mechanism in the direction of the arrow 52. During this movement the column 19 is both raised and slightly tilted counter-clockwise as viewed to allow it to clear the edge of the deck with greater clearance. All the hydraulic mechanisms are provided with a mechanical back-up for safety in the event of failure. It is envisaged that hollow hydraulic cylinders be used with a rope passing centrally down the column 19 and around a winch 70. In the event of hydraulic failure, the valves of the hydraulic system may be opened and the workplatform winched mechanically to safety. Though the shorter arm of the retraction mechanism is shown secured to the deck 30, it may alternatively be on rails to permit positioning of the work platform wherever desired on the deck. In such an instance, anchoring means may additionally be provided to prevent movement of the wheeled trolley supporting the work platform while the platform is in use. CLAIMS (Filed on 15 April 1982)

1. A workplatform having a support structure comprising a first arm capable of rotation about a vertical axis and suspended at an adjustable height beneath deck level and a second arm pivotably mounted on the end of the first arm and supporting the workplatform.

2. A workplatform as claimed in claim 1, wherein the first arm is secured to the lower end of a telescopically collapsible column which is rotatable about a vertical axis.

3. Aworkplatform as claimed in claim 2, wherein the first arm is secured to the support column in a manner so as to be pivotable in a vertical plane.

4. A workplatform as claimed in any preceding claim, wherein the first arm is formed of several telescopically collapsed sections to permit accurate positioning of the platform over an extended radius centered on the said vertical axis.

5. A workplatform as claimed in claim 4, wherein a motor is provided for articulating the second arm about the first arm and the motor and the telescopic components are hydraulically operated.

6. A workplatform as claimed in claim 5, wherein a manual operating system is provided so as to allow movement of workplatform in the event of a hydraulic failure.

7. A workplatform as claimed in any preceding claim and claim 2, wherein the support column is suspended beneath deck level.

8. A workplatform as claimed in claim 7, wherein the support column is suspended from a trolley which is guided on rails secured beneath deck level.

9. A workplatform as claimed in any of claims 1 to 6 and claim 2, wherein the support column is mounted on a retraction mechanism for permitting the column together with the first and second arms to be raised above deck level.

10. A workplatform as claimed in claim 9, wherein the retraction mechanism comprises a quadrilateral pivoted structure having two short arms and two long arms, one of the short arms being secured above deck level and the other serving to support the support column.

11. A workplatform as claimed in claim 10, wherein the retraction mechanism is hydraulically operated.

12. Aworkplatform as claimed in claim 10 or 11, wherein the short arm secured above deck level is secured to a trolley for movement on rails secured above deck level.

13. A workplatform substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.