MARITIME

FPSO First
Modec converted the
Whakaaropai in 1996
Photo: Modec
risers in production. This class insufficiency
might be behind the Norne decision
to study, inspect and overhaul at
sea despite the omnipresence of class in
Norway.
Atypical for class are issues like external
riser damage and corrosion in
mooring suction piles. Anchor cracks
… “They’re not really inspected for
fatigue,” says Anaturk. His other lifeextension
pointers include making sure
offloading buoys get modern floating
hoses. “It’s the most vulnerable part of
the FPSO,” he says, and it’s highest on
his chart of costly consequences. Topsides
and hull corrosion, too, come in at
the top of the dangerous items list. Finally,
he recommends decoupling schedules
for flow lines and FPSO start-up or first
oil might have to wait several months,
as is understood to have happened at
Bonga.
Repair or Replace
Top of the “expensive” list of fixable
items are the rotating equipment pressure
declines that often seen just as
life-extension is being contemplated.
Cavitation, which is damage caused by
the formation and implosion of vapor in
pump systems, can also cause disruption.
David Arnold of Weir Services has been
called in at times to repair or remove a
turbine rotor only to find that the turbine
blades alone were damaged, a specialty
repair for Weir crews. His workshops
ID the material or part — both of which
might no longer be in production — then
reverse engineer using the scanned data
of a laser “pen” scanner. For owners or
contractors facing turbine problems in
power, injectors, compressors or pumps,
speedy repair could in itself mean a life
extended. He warns that the savings
that might be found in repairs alone for
life-extension shouldn’t be the only parameters
used. “If you change service
provider on cost alone you’ll be taking a
great chance,” says Arnold.
Optimum Life
Marco Beenen, Senior Vice President
for BW Offshore’s West Africa Fleet, is a
proponent of life-extension taken to sea.
“Most units have significant remaining
technical life,” says Beenen, a veteran
of four FPSO life-extensions: Petrolea
Nautipa, now 14 years beyond contract;
Espoir Ivoirien (14 years); Sendje Berge
(seven years) and the Abo (13 years).
“FPSO replacement is rarely a viable
option for the client,” says Beenen,
pointing to a BW record he says speaks
of extra contract value. “You can come
up with your own numbers, but the BW
view is that life-extension can reach 20
to 30 years,” he says, adding that some
have been BW Offshore “signature
modifications” that last two to five years,
as on some models afloat in the Gulf of
Mexico, Brazil, the North Sea, New Zealand
and West Africa.
Beenen reveals the company bought
several 1970s (single-hull) tankers and
converted them into FPSOs with smaller,
isolated total holds to measure up to today’s
double hull safety.
“Tankers built in ’76 are actually in
fantastic condition. They show signs of
having been built better than some modern
tankers,” he says.
Beenen says, “in-situ modifications are
often the best choice” for the client, and
he points to one West African example
where life-extension was made possible
by life-saving repairs. A metal-eating
bacteria peculiar to Africa had infected
a bulkhead in the Berge Helena and had
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