This method (see Figure A.28) is normally used for a second-end tie-in, where the lay vessel pre-installs buoyancy and chains at predefined locations along the flowline or umbilical. After the end of the flowline or umbilical is installed inside a predefined target area, the tie-in vessel releases the line and surveys it to ensure suitable positioning and buoyancy. The pull-in head on the end of the line is then connected by a wire, routed via the subsea equipment to which the line is to be connected, to a pull-in winch. The line is then deflected so that the pull-in head is positioned in front of the pull-in porch of the subsea structure. The pull-in and connection tools are then used to complete the tie-in, along the same principles as for a normal pull-in. As the line is normally deflected in an empty condition, water-flooding is performed prior to the make-up of the connection.
Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards