Design and construction of lift cable latching system for Trenchformer
Auxilium Offshore has been asked to perform the design and construction for a lift cable latching system in order to (dis)connect the lifting cable from the Trenchformer subsea and on deck. Major challenge was engineering and designing in a critical envelope due to the existing lifting configuration (Swingbeam / A-frame) of the system.
The main requirements for the system are the following:
Design requires a Safe Working Load (SWL) of 55mT with a Dynamic Amplification Factor (DAF) of 2;
Able to connect and disconnect subsea also in emergency situations (i.e. power black-out of the vehicle);
Able to compensate the Centre of Gravity (CoG) for the different trencher set-ups (jetting vs. cutting);
System should fit on the existing trencher and interface with existing Swingbeam / A-frame without any modifications.
The system exists of an outer frame which can be mounted to the trenchers’ existing mainframe. In this outer frame a latching bucket is positioned (to compensate for the different CoGs).
The latching bucket exists of 4 spring loaded latches and a catcher for the docking pin. The docking pin can be mounted to the existing interface of the Swingbeam / A-frame.
The 4 spring loaded latches can be opened manually to disconnect the docking pin by using 4 small hydraulic cylinders and are only able to open the latches without the suspended load of the trencher.