Method for installing an elongate element in a stretch of water, and associated device and installation

A device for introduction of an elongate element in a stretch of water, comprising:

• a connecting member adapted to be reversibly attached to a first end of the elongate element;
• an assembly for moving the elongate element into a substantially horizontal configuration along a surface facility;
• a retaining member intended to project with respect to the surface facility, the connecting member being reversibly movable between a starting position in which it is disengaged from the retaining member and a lowering position in which it is engaged in a reversible manner in the retaining member;
• a mechanism to pivot the elongate element about a substantially horizontal axis in order to move the elongate element into a substantially vertical configuration, wherein the connecting member remains engaged in the retaining member, wherein the substantially horizontal axis for pivoting the elongate element is located in a vicinity of the first end of the elongate element selected for enabling the pivoting of the elongate element into the substantially vertical configuration;
• and
• an assembly comprising the retaining member, the connecting member and the elongate element for joint lowering into the stretch of water having a lowering line carried by the surface facility,
• wherein the retaining member is suspended from a support frame via the lowering line by which the support frame for the retaining member is fixed to the surface facility and projects with respect to the stretch of water.

A method for installing an elongate element in a stretch of water, comprising the following steps:

• reversibly fastening of a connecting member at a first end of the elongate element;
• engaging a first movement line on the connecting member and engaging of a second movement line at a second end of the elongate element, the elongate element being suspended between the first movement line and the second movement line;
• maneuvering the first movement line and/or the second movement line to arrange the elongate element in a substantially horizontal configuration along the surface facility;
• reversibly engaging of the connecting member in a retaining member projecting with respect to the surface facility;
• pivoting the elongate element into a substantially vertical configuration by lowering the second movement line and the second end of the elongate element with a crane under the stretch of water and under the first end of the elongate element, the second movement line remaining stretched and taking up a part of the weight of the elongate element, the retaining member remaining substantially vertically stationary during the lowering;
• jointly lowering of the retaining member, the connecting member and the elongate element in the stretch of water with a lowering line carried by the surface facility;
• detaching of the connecting member of the first end of the elongate element, and jointly raising of the retaining member and the connecting member;
• suspending the retaining member from a support frame via the lowering line, whereby the support frame for the retaining member is fixed to the surface facility and projects with respect to the stretch of water.