FLOWLINES & PIPELINES
Castorone extends the threshold
for deepwater, large-diameter pipelay
Vessel starts work on Walker Ridge in Gulf of Mexico
The offshore market will increasingly require lay vessels capable of install- ing large (more than 24-in.) diameter trunklines in all water depths, with more advanced dynamic positioning
(DP) capability and higher pipe storage capacity for remote locations.
With all these issues in mind, Saipem has
engineered and constructed its latest fagship
vessel Castorone, which can perform S-lay in
shallow waters and steep S-lay in deepwaters
(more than 2,000 m/6,562 ft), switching to
J-lay mode for ultra-deepwaters (up to and
more than 3,000 m/9,842 ft) or where the
project requirements limit pipe bending and
longitudinal stresses. This versatility has
been achieved through numerous distinctive
features such as a DP- 3 dynamic positioning
system designed for pipelay; a high bollard
pull to counteract pipe bottom tension; and
a ramp system with pipe roller supports that
is fully remote-controlled without having to
abandon the pipe, and capable of attaining a
near-vertical ramp exit angle.
The vessel is classifed Ice Class AO (IA
Baltic), allowing it to handle S-lay of trunklines
even in arctic conditions. Its transit speed is
13 knots, and its storage capacity is around
20,000 metric tons ( 22,046 tons), with the
possibility to upgrade to unmanned loading
and offoading of pipe joints.
Castorone has started its first assignment in the US Gulf of Mexico. All photos courtesy Saipem.
Castorone is 330 m ( 1,082 ft) long, excluding the ramp/stinger and helideck. Its molded breadth is 39 m ( 128 ft), with a transit draft
of around 8 m ( 26 ft), and a maximum operating draft of 10 m ( 33 ft), with a displacement
of 100,000 metric tons ( 110,231 tons) at maximum draft. The vessel can S-lay in DP mode
pipes up to 60-in. diameter and pre-fabricate
onboard pipe strings 36 m ( 118 ft) long, with
the unique capability of joining 2 x 18-m ( 2 x
59-ft) long pipes as an alternative to 3 x 12-m
( 3 x 39-m) conventional joints.
The stinger is designed to handle any pipe
diameter and water depth through continuous
control of overbend stresses in the pipe. The
stinger comprises three articulated, adjustable
sections allowing a change of confguration
from shallow to ultra-deepwater without abandoning the pipe – another unique feature. Up
to seven triple joint work stations may be used
to assure a high production rate. Pull capacity
is 750 metric tons (827 tons), with a maximum
holding capacity for fooded mode of 1,500
metric tons ( 1,653 tons).
Castorone’s main crane can lift 600 metric
tons (661 tons) at 30 m ( 98 ft), and 350 metric tons (386 tons) at 46 m (151 ft). Additionally, there are two pipe handling cranes and
a pedestal crane for loads in the 30-52 ton
range. There is accommodation for 702 personnel and a helideck designed to accommodate a Sikorsky S- 61 helicopter.
The vessel’s design allows for the future
installation of a fxed tower for double-sta-tion, triple-joint J-lay in ultra-deepwater. A
fast switchover from S-lay to J-lay will be possible offshore and while serving the same
project to best accommodate the route and
water depth needs.
In J-lay mode the pipe is laid through a ver-
tical ramp, positioned to allow a more natu-
ral laying confguration. As a result, a lower
lay tension is required, leading to reduced
on-bottom tension. In addition, J-lay is less
impacted by weather, and pipe stresses are
maintained well within the linear elastic limit.
Into the fring line
At the portside and starboard, two gantry
cranes lift line pipe brought from supply ves-