Tsubaki Kabelschlepp Group
TechnipFMC’s North Sea Giant is one of
the largest subsea construction ships ever
built, with a length of 161 m (528 ft) and a
breadth of 30 m (98 ft). It is equipped with two
cranes, driven by five Voith Schneider propellers, and is designed for extreme deployments
in high seas.
AXTech in Molde, Norway, supplied the
420-ton lift capacity SHS tower crane for
installing and maintaining subsea structures,
which has a movement span of 180°, allowing
heavy equipment to be lifted from the deck
into the sea. Transportation of the loads is
ensured by more than 15 hydraulic hoses
rated to around 450 bar ( 6,526 psi). Due to
the crane’s circular movement, it is necessary to guide the hoses during operations to
ensure a secure power supply to the crane.
The combination of extreme sea conditions
and swinging loads makes this power supply a
critical interface in ensuring the function and
safety of the entire facility.
To help achieve a maximum safety and service life for the crane, a cable carrier was the
chosen method for routing the hoses, supplied
by Tsubaki Kabelschlepp. The system is configured to guarantee the power supply to the
base of the crane, a few meters above the water level, at any time, and to withstand regular
exposure to salt water. The system must also
guarantee the necessary stability required due
to the ship’s movements in rough seas.
When planning started for the solid stainless
steel cable carrier, construction space restric-
tions on the vessel’s deck necessitated an adap-
tation of the design of system and its support-
ing structure. This led to a solution developed
in close co-operation with the client’s various
technical departments, using 3D simulations
to comply with construction space specs and to
model the impact of the harsh conditions.
Production of all parts of the cable carrier
was strictly controlled and inspected to ensure
the required quality. Due to the environmental
conditions and the potential risks posed by
a failure of the cable carrier, each screw was
subject to a burden-of-proof of meeting the
To ensure the reliability, stability and func-
tionality, the entire cable carrier system was
installed and tested at Tsubaki Kabelschlepp’s
facility, witnessed by AXTech and its end-
customer Statoil during a factory acceptance
test. The test set-up and process were subject
to stringent safety precautions. Within the
scope of testing, a high-pressure test was
stipulated of the hoses while moving the cable
carrier. In this instance, the tubes were filled
to a rating above 450 bar to simulate actual
conditions on board.
Tsubaki Kabelschlepp was also responsible
for installation and commissioning of the
system: due to time pressures and installation
costs at the offshore location, the company
was asked to speed up the installation from
the originally estimated 15 days. It responded
by engineering the steel structure in a way
that facilitated pre-assembly in a construction hall in order to subsequently raise these
various parts onto the ship in the shortest
possible time and with only three lifts. In this
way, both the assembly time and the resulting
costs were drastically reduced.
The stability and load-carrying capacity
of the system were tested in advance using
modern calculation programs to ensure the
safe lifting process from land to ship. Using a
highly variable mounting system, the entire
system was installed on board the North Sea
Giant quickly and safely and below the predetermined tolerance conditions. The vessel has
since been operating offshore for two years
successfully with the new crane system. •
Weatherford International plc has announced the commercial
release of the ISO Extreme retrievable well barrier, which is qualified
to ISO 14310 V0 standards for gas-tight isolation.
The company says that the barrier has a large operational envelope, capable of withstanding pressure differentials up to 10,000 psi
( 68.95 MPa) and temperatures between 40 and 325°F ( 4 and 163°C),
which reduces the loss-of-containment risk in extreme environments.
ISO Extreme well barriers are available for tubing sizes from 3. 5
through 7 in. The variety of deployment options — including electric
line, slickline, tubing and coiled tubing — further increases operational flexibility.
Unlike comparable technologies available for the high-pressure/
“We are pleased to add the first V0-qualified and field-proven HP/
HT well barrier to our industry-leading portfolio of wellbore isolation
technologies,” said Mark Hopmann, Vice President of Completions at
Weatherford. “With this addition, we now have a comprehensive of-
fering of well barriers for diverse applications and environments.” •
Stainless steel cable carrier adapted for North Sea Giant deck constraints
Weatherford introduces V0-Qualified retrievable well barrier
Left: Tower crane on the North Sea Giant. (Photos courtesy Tsubaki Kabelschlepp)
Right: Factory acceptance test of the cable carrier.
Weatherford says that its ISO Extreme retrievable well barrier enables passage through typical wellbore restrictions for easy deployment and removal.