Patent GB-1307251-A (GB)
Title: Method and apparatus for laying pipelines
IPC: F16L1/18
Filed: 1970-03-10
Abstract: 1307251 Laying pipe-lines BROWN & ROOT Inc 10 March 1970 [9 April 1969] 11433/70 Heading F2P Apparatus for laying a pipe-line 3 on a submerged surface 2 from a floating vessel 5 comprises support means to support a pipe-line from the vessel, a first detecting means operable at least periodically to detect at least an indication of a vector component of tension exerted on the pipe-line from the vessel, a second detector means operable at least periodically to detect at least an indication of a vector component of force interacting laterally between the vessel and the pipe-line and directed generally transversely of the pipe-line, a third detecting means operable at least periodically to detect at least an indication of the position of the vessel relative to a desired course and vessel propulsion control units operable in response to the detecting of the said vector components and the vessel position, to adjust the thrust effect of the vessel propulsion units 6 to tend to maintain the forces exerted on the pipe-line and the position of the vessel within predetermined limits. The support means preferably includes clamping means 19 (Figs. 5 and 6, not shown) operable periodically to grip the upper portion of the pipe-line and yieldable tensioning means 18 of the torque wheel type (Figs. 2-4, not shown) operable periodically and alternately with the clamping means to tension and to feed the pipe-line relative to the vessel. A stringer 12 adjustably hinged to the vessel (Fig. 7, not shown) may form part of the support means and comprises a number of segments 13 articulated at 14 and provided with jacks (15, Fig. 8, not shown) to adjust the angle between segments. The jacks can be manually or remotely operated and the buoyancy of the segments is also adjustable. The segments 13 are provided with load cells to determine vertical and transverse forces acting between the pipe and segment and these can constitute force detecting means referred to above. They can also be used to adjust the buoyancy and positioning of the stringer segments to maintain full support for the pipe within predetermined limits of bending. The segments 13 can also be provided with clinometers for adjustment purposes. Load cells are also associated with the gripping and the tensioning devices to determine the tension and transverse forces acting between the pipe and the vessel and these may also act as the force detecting means referred to above. Detection of the position of the vessel may be done with the aid of an orbiting satellite 116 and a sonar beacon 117 positioned along the desired course or by other navigational aids. The vessel preferably has six propulsion units suitably positioned on the hull (Fig. 15, not shown) each adjustable as to magnitude and direction of thrust. The detector means referred to detect tension deviation, lateral load deviation and position deviation and these are used together with various other factors to produce tension corrections, turning moment corrections and position corrections to control the propulsion units. This can be done by manual operation but preferably a computer (see Figs. 18 and 19, not shown) is used into which the detected information and other factors are fed at regular intervals and the output used to control the propulsion units, a console with various indicators and alarms (Fig. 24, not shown) being provided for monitoring the operation. Priority is given to the tension and lateral force corrections within the limits of available thrust from the propulsion units.