GB904854A - Underwater pipe-line installation - Google Patents

Abstract

904,854. Submarine pipe-lines. WITTGENSTEIN, G. F. May 1, 1961 [May 11, 1960; June 9, 1960; Sept. 2, 1960; Jan. 18, 1961], No. 15634/61. Class 99(2). A method of laying a submarine pipe-line 1 comprises the steps of arranging a predetermined number of motorised craft T along a sector of the pipe line at intervals correspending to the eventual points of attachment of the pipe-line to anchor weights, the craft each having a cable 5 coiled on a winch and at least one anchor weight B, passing the end of each cable through a cable locking device around a drum 4 associated with the weight and temporarily securing that end of the cable to the craft, lowering the weight to the bottom whilst allowing the cable to unwind from the winch so that the cable runs on the drum, disconnecting the end of the cable from the craft and fixing the cable to a pipe-line attachment device 6 operatively associated with the locking device, winding the cable on the winch drum so as to haul the pipe-line attachment device and pipe-line down to the required predetermined depth, and operating the locking device to maintain the pipe-line attachment device in the required position when the cable has been finally disconnected from the craft. The locking device as shown in Fig. 6 comprises a lever 11 keyed to a shaft 10 which carries a cam 14. Mounted on the lever are a weight Q and buoyant mass 13, and a sleeve 15 embracing the cable 5, when the cable is slackened, allows the lever to pivot so that the cable is jammed against the frame 6 by the cam. Re-tensioning of the cable unlocks the latter. Alternatively, a ring, bearing on the sleeve 15, produces the rocking movement of the lever. The cable 5 may be looped about the pipe-line, passed around a drum 4 of a weight B and locked by a sleeve co-operating with a plate. As a result of filling the pipeline with the material which is to be conveyed thereby and to prevent appreciable change in the buoyancy of the pipe-line sinkers 21, Fig. 8, are attached to the pipe-line and comprise e.g. a concrete block suspended from the pipe by a hook 20 and connecting members 22, 23, the hook being closed by a latch 24 held in place by a pin 25; the latter is sheared by a pull on a cord 26 to open the hook and release the sinker. The pipe-line may comprise inner and outer pipes, the former being e.g. of synthetic plastic material and conveying a liquid gaseous hydrocarbon and the outer pipe being filled with a gas.