Showing papers on "Submarine pipeline published in 1973"

Method and apparatus for laying large diameter pipeline segments offshore

Abstract: A method and apparatus for laying a pipeline upon the bed of a body of water. The apparatus includes a generally cylindrical male member operable to be positioned within the interior of one of a submerged pipeline segment and at least one pipeline segment to be laid. Operating in conjunction with the male member is a female member which is designed to be positioned within the interior of the other of the submerged pipeline segment and at least one pipeline segment to be laid. Expandable circumferential friction collars are mounted upon the male and female members to releasably secure the members within the interior of the pipeline segments. A flexible cable is securely connected to one of the male and female members operably connected within the pipeline segment to be laid and extends through the other of the male and female members operably positioned within the interior of the submerged pipeline segment for aligning the male and female members within the body of water. Following alignment, the flexible cable may serve to pull the male and female members into stabbing engagement and one end of the pipeline segment to be laid into abutting contact with the free end of the submerged pipeline segment. The method includes the steps of positioning one member of a male and female member guide assembly within the free end of a submerged pipeline segment and positioning the other member of the male and female member guide assembly within at least one pipeline segment to be laid. The guide member positioned within at least one pipeline segment to be laid is fitted at one end with at least a first cable and at the other end with at least a second cable. The guide members and the at least one pipeline segment to be laid are lowered into body of water and the cables are tensioned to align the male and female member guide assembly within the body of water. Following alignment the male and female members of the guide assembly are interocnnected and stabbed into full engagement to position the pipeline segment to be laid in abutting contact with the free end of the submerged pipeline segment. The one member of the male and female member guide assembly which is connected to the free end of the submerged pipeline segment is then axially drawn to the free end of the thus laid at least one pipeline segment. The other member of the male and female member guide assembly is then disconnected and raised to the surface to be positioned within another at least one pipeline segment to be laid.

Method and apparatus for working with offshore pipelines

Abstract: A technique and apparatus for laying offshore pipelines wherein the manipulating of a pipeline is controlled in response to visually observed relationships between a preplotted pipeline route and the plotted actual position of a pipeline lay barge.

Design criteria for submarine pipeline crossings

Abstract: This laboratory investigation of pipeline crossings of alluvial streams shows that the rate of scour above the pipe varies as the dimensionless shear stress which is a function of the grain size, the energy slope, and the hydraulic radius. The dimensionless shear stress is used to determine the depth of scour that will occur for various flood discharges. The use of rock riprap protects the pipe from being washed out during floods. Prototype size of riprap may be computed according to the two following criteria: (1) geometrical similarity; and (2) fall velocity. The coefficients of drag and lift are plotted against a modified Froude number so that drag and lift forces can be computed for exposed prototype pipes.

Rapid consolidation of fluidized sand bed

Abstract: Method and apparatus for obtaining rapid consolidation of the fluidized sand mass on top of a submarine pipeline buried in the bottom of a body of water by fluidization of the bottom. Rapid consolidation is obtained by reducing the flow rate of the water injected into the bottom to about a third of the minimum flow rate necessary for fluidization of the bottom.