This method (see Figure A.25) aligns the flowline or umbilical by pulling it toward its connection point using a wire rope(s) fastened to the flowline end (pull-in head, see 3.1.8). Final alignment and positioning typically requires special tools and/or alignment frames. Temporary buoyancy or flexible jumpers can be used to reduce pull-in forces and moments. In diverless situations, the pull-in is conducted through the use of ROTs. These tools are designed with enough power to pull, lift, bend and rotate the line into its final position at the connection point. The same tool can also assist in locking the flowline or umbilical to the connection point and testing the connection.
Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards