GB1196992A - Improved Floatable Structure - Google Patents

Abstract

1,196,992. Subaqueous structures; lighttowers. VICKERS Ltd. 17 March, 1969 [19 March, 1968], No. 1335/68. Headings E1H and E1A. A floatable well-head-platform structure comprises a column 1 that is freely-floodable and houses a tubular trunk 15 supporting a platform 8 and working deck 9, a base part 2 being furnishedwith a working chamber 13 that can be entered by personnel through the trunk and is surrounded by an annular floodable-buoyancy-chamber 7. To facilitate removal of the structure to and from the site of the well-head the chamber 7 can travel vertically and be secured to either the column or the part 2. The watertight baseplate 5 contains means of access (not shown) to the sea floor from the chamber 13 and may be wholly or partially removable to improve said access. Ring bulkheads 6 with radial webs 3 therebetween establish a seal about the aforementioned means of access. When the structure is in situ the chamber 7 is flooded through valves 17 and rests upon the part 2 as shown; and when the structure is to be removed the chamber 7 is partially charged with air by a compressor 11 so that it rises to the surface of the water. After being secured to the column the chamber 7 receives more air until it raises the structure above the sea bed, the column being subsequently lifted relative to said chamber by jacking mechanism (not shown) to reduce the draft of the structure. The base part may be capable of separation from the rest of the structure, in which case a conic spigot 20 and socket 19 are provided on said part and the trunk, respectively, and a further buoyancy-chamber 32 of horseshoe shape is provided to facilitate removal of the column I while leaving the base part in situ. Access hatches 16, 23, 28, 31 are provided as shown when the column is separable from the part 2 so that the latter can be left on the sea bed and the rest of the structure removed; otherwise the hatch 16 only is provided and located at the top of the chamber 13, Fig. 1 (not shown). Compressed air can be supplied to a chamber 24 through a pipeline 25 to form an air lock. Lead shot for ballasting purposes may be placed in the chamber 7 through a pipeline 18. Piles (not shown) may be arranged around the bulkheads 6 to minimize leakage thereat and may be driven by the structure as it descends and/or driving means incorporated in the structure. The structure may be adapted to deeper water by extension columns and trunks fitted when in situ. The structure may be modified for use as a lighthouse or tower, the trunk 15 and chamber 13 being used for storage purposes.