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Technology
Update
46
J
uly
/A
ugust
2007
Nexans Norway, part of the Nexans
worldwide group of cable manufactures,
specialises in the production of sub-sea
power cables and umbilicals, and has
already delivered approximately one
hundred umbilicals.
Modern umbilical cables are not simply
thousands of metres of assorted wires
within a waterproof outer wrapping or
container. The umbilicals, manufactured by
Nexans at its Halden plant, normally contain
between three and twenty super duplex
tubes which contain various fluids. Each
tube is fabricated in up to 20km or more.
All tubes and other elements (power and
fibre) in the umbilical are laid up, armoured
and finally protected by a PE-sheeting. The
umbilical itself varies in size from 75mm to
300mm OD.
There is no room for planned obsolescence.
Once buried underwater, sometimes as
deep as 2,000m, these umbilicals are
difficult to repair. The quality must be
impeccable and both the customer and
the manufacturer must have the utmost
confidence in the manufacturing process.
Nexans begins its process with 12m
to 40m lengths of super duplex tubing,
welding them into lengths up to 20,000m
or more, the capacity of its enormous reels.
The umbilicals are used to control sub-
sea offshore equipment from a platform,
production ships or directly from onshore.
The company is currently producing the
Ormen Lange 1 umbilical for Norsk Hydro,
which will reach 120km from shore in
Norway to the sub-sea field, and will contain
seven super duplex tubes. The umbilical,
one of two, will contain approximately
37,000 welds, and will supply hydraulic
fluid, electrical power and control signals
(via integrated fibre optics) from the
onshore gas processing facility at Nyhamna
on the west coast of Norway to the sub-sea
production systems.
Ormen Lange is the largest gas field under
development on the Norwegian continental
shelf, and is located 100km off the
northwest coast of Norway at a water depth
of 850 to 1,100m. The gas from this field
is transported to shore for processing and
Orbital welding increases longevity for underwater umbilicals
fi
A Nexans production line
›
PC transistorised power source with numeric
control