GB1191146A - Improvements in or relating to Buoys and Methods for Transporting and Laying Submarine Pipe Lines - Google Patents

Abstract

1,191,146. Laying underwater pipe lines. CONSTRUCTEURS ASSOCIES POUR LE MONTAGE D'OUVRAGES METALLIQUES. 12 June, 1967 [13 June, 1966], No. 26972/67. Heading F2P. A buoy for the supporting, or immersion, of submarine pipes comprising a cylindrical tank 1 divided by a central partition 5 into an upper compartment 1 and a lower compartment 2 is characterized in that the lower compartment 2 has, at its base 4, a member 6 enabling it to be filled with water, the upper part of the lower compartment 2 being joined to a tube 7 passing through the upper compartment and ending in a plug 8 at the upper part of the upper compartment 1 for controlling the evacuation of air, and in that the base 5 of the upper compartment communicates with the outside through a pipe 12, or 17, passing through the lower compartment 2 and opening out into the outside at the base of the lower compartment through a water inlet member 14 or 16, which controls the filling of the upper chamber 1. A supporting buoy, Fig. 1, has its lower compartment filled with water through a valve 6 the evacuation of air from this compartment being controlled by the vent plug 8, the upper compartment being filled through the pipe 12 the lower end of which communicates with the surrounding water through a burstable diaphragm 13 protected by a plate 14. The buoy body has upper and lower connecting bows 9, 11 and a lower protector skirt 10. The immersion release buoy is of generally similar construction, but, in this case, the filling of the upper chamber 1 is carried out by operating a valve 16 at the base of a pipe 17, in conjunction with a screw plug 18 which closes a vent orifice 19. A series of buoys (20) of both types, with their lower chambers filled to a level to give good stability, Fig. 3 (not shown), are connected by ropes (21) to a pipe line (22) for towing to a pipe laying site where the lower chambers (2) are completely filled so that the buoys approach their buoyancy limit, Fig. 4 (not shown). The upper chambers 1 of the immersion release buoys are then controllably filled so that these buoys are immersed and carry with them the supporting buoys which are filled against the compression of air in their upper chambers 1 when they reach a depth sufficient to rupture their diaphragms 13, the pipe line 22 being gradually lowered until it rests on the sea bottom. The pipe (22) is towed in a channel bounded laterally by beacons (23) (Fig. 8, not shown), which have their lower ends at a greater depth than the pipe line (22) and are mainly for guiding the pipe line (22) round curves. To this end the beacons (23) are swivelly connected by means of swivels 24 to mooring ropes (25) and each buoy (20) is connected to the pipe line (22) by means of a rigid rod 21a and a flexible chain 21b.