FSO conversion timesaver: Miko magnetic closures

Closure is held in place on Randgrid by Miko Magnets

APRIL 12, 2017 — Teekay is currently converting the 1995-built, 124,502 dwt VLCC Randgrid into an FSO (Floating Storage and Offloading) vessel at Singapore’s Sembawang shipyard with work that includes installation of an internal turret mooring system. When the conversion is complete the new FSO will be operated by Teekay on Statoil’s Gina Krog field in the North Sea.

Oslo, Norway, headquartered Miko Marine has delivered four unique magnetic sea chest blanks for use during the conversion work.

The Miko closures are now on site and ready to be used to create safe conditions for technicians working inside the vessel’s sea chests. Because magnets attach to the hull instantly they are seen as a valuable means of saving time and costs when compared with other methods used during typical underwater engineering work.

The Miko hull closures are new to the ship repair industry and are a development of designs previously supplied to and proven by Odfjell Drilling which used them on the Deepsea Stavanger semi-submersible platform.

Because the closures are each held in place against the vessel by powerful permanent magnets, valuable time savings are achieved when compared with the methods traditionally employed for closing sea chests.

To ensure that the closures have a perfect fit against the curved profile of the hull, Miko Marine carried out 3D laser scanning and precision measurements in the Sembawang dry dock last year to enable precision manufacture of the blanks andyear and manufacture was completed in time for their delivery in January.

The Randgrid project is a new demonstration of Miko expertise in its specialized applications of magnetic technology. This application is unique due to its use of four or eight powerful Miko MAM permanent magnets, depending on the size of the closure. With each magnet being capable of holding up to 450 kg it is possible to achieve an immediate watertight seal for the closures, without the need for any other fastening devices being fitted to the steel hull. Flotation material is integrated within the blanking plates making them neutrally buoyant and easily handled under water by ROV.

Each magnet used is attached to its closure by a special rubber link that introduces an element of flexibility so the plate can be positioned precisely and fitted flush against the hull before it is tightened into place.

When the repair work is finished each magnet is simply freed by having its release lever lifted by a diver or ROV so the blank can be quickly retrieved by crane.