Direct vertical connection method
In this method (see Figure A.29), the flowline terminates in a hydraulically actuated connector that is landed directly onto a vertical hub located on the subsea structure. All operations are conducted by the sealine installation vessel itself. After being landed, the connector is locked to the hub by applying hydraulic pressure via either an ROV tool or a hydraulic hot-line from the surface.
Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards