5007 Stevmanta/te 2004

Stevpris Mk5
The Classic Anchor
The most applied
offshore anchor
Introduced in 1993,
the Stevpris Mk5 anchor was the
ultimate fine-tuned version of its
already successful predecessors.
Since then the anchor has become
the world’s most used offshore
anchor, primarily because of its
principle qualities; it has the
highest holding power available,
and it accommodates
the widest range
of soils possible.
The majority of the Stevpris Mk5 anchor
applications are found in permanent
mooring systems suchs as FPSOs, FSUs,
SPMs and in temporary mooring systems
for mobile drilling units (MODUs).
The 2,200 Stevpris anchors currently in use
moor units in both shallow and ultra deep
waters. Stevpris serves both mobile and
permanent applications equally well, as it;
■ is easy to handle
■ is easy to install
■ is easy to retrieve
■ has uplift capability
Stevpris Mk6
In recent years, loads at the anchor point
have increased and correct anchor handling
has become the focus of many. Customer
feedback on the use and requirements of
drag anchors sparked the introduction of
the Stevpris Mk6 in 2003. Stevpris Mk6 has a
30% higher holding capacity and increased
structural strength and has already become
the anchor of choice for most applications.
Stevpris Mk5
Stevpris Mk5
1 Vryhof shackle design allows for easy chaser passage.
1
2 Pad-eye serves for connecting a pennant line or a piggy-back
anchor.
2
3 Narrow shank holds the chaser for an effective working
position during chasing operations.
3
4 Wings turn the anchor into position for retrieval over stern
roller of an AHV.
4
5
5 Self-burying prismatic V-shaped shank allows soil to easily
pass through, promoting rapid anchor penetration.
6 V-shaped shank with widely spaced attachment points to the
fluke, allows for a large fluke area.
7 Smooth and rounded shank shape prevents damage to the
AHV deck and stern roller during deployment and
retrieval.
8 Fluke/shank angle is adjustable (32, 41, 50 degrees)
without welding to meet maximum performance in
all soil types.
9 Hollow fluke allows ballasting to assist initial
penetration in very hard soil.
10 Stabilizers to assure a balanced
penetration.
11 The widely spaced fluke tips assure
stability of the anchor when
seated on the seabed.
7
10
8
6
9
11
The Classic Anchor
Easy handling
Increased awareness of safety on
deck makes it risky to use unstable
drag anchors. The low point of gravity
of the Stevpris Mk5 when lying on
deck makes it the safest choice.
The lifting pad eyes make it easy
and safe to lift the anchor.
20 uplift
0 uplift
Stevpris Mk5
Easy installation
The Stevpris Mk5 is easily and safely handled from the deck
The anchor’s shank shape assures stability on deck, the low
of an AHV. Stevpris Mk5 can take considerable uplift loads,
centre of gravity assures an upright landing on the seabed,
experience shows that 200 uplift is possible without significant
where the wide spaced fluke tips assure its stability. Stevpris’
reduction in UHC. Classification authorities allow 50 uplift in the
shape assures stability during penetration.
0
intact load condition and 10 in the damaged load condition.
Easy retrieval
Anchor Manual 2010
The Guide to Anchoring
A
Capelle a/d Yssel
T
After having been embedded for some time, suction and
friction forces acting upon an anchor will aggravate its retrieval.
However, because of the long shank, retrieval forces will
generate a large moment forcing the Stevpris anchor to rotate
and consequently overcome these forces. It can therefore
be retrieved at 60-80% of the pull-in load (soft soil) or at
20% in harder soils.
Easy Handling
Vryhof's Anchor Manual is used throughout the
industry and describes proven installation & retrieval
methods for all its anchors. The Anchor Manual can be
downloaded from the Vryhof website www.vryhof.com
A solid basis
For 15 years Vryhof
has been building a database
of relevant soil data and
performance records from the
locations worldwide where their
anchors have been employed.
These data prove invaluable for
Vryhof’s marine engineers
and soil specialists to
support their clients’ operations.
The database has allowed the
development of empirical
formulas which allow Vryhof to
recommend the most
optimal anchor size and predict
drag and penetration for a
specific soil and load condition.
Free engineering
Vryhof is known for its pre and after
sales services. Clients can freely rely on
recommendations for equipping floating
units with an anchoring or mooring system.
Such advice mostly comprises choice of
anchor type and size, installation procedures,
chaser or pennant line and compatibility of
anchor line jewelry. It also includes matters
such as a matching fairlead and anchor rack.
General information on these aspects is also
summarized in the Vryhof Anchor Manual,
freely available on request.
Quality manufacturing
Stevpris anchors are manufactured to
ISO9001 standard. The anchors have type
approval and are certified by ABS, BV, DNV,
Lloyd’s, NKK, RINA and USSR Register of
Shipping for both Mobile Offshore Units
and Permanently Moored Units.
Stevpris Mk5
Ultimate holding capacity
The prediction lines on the UHC chart represent the equation
UHC= A*(W)0.92 with UHC as the ultimate holding capacity
in tonnes and A a parameter depending on soil, anchor and
anchor line with values between 24 and 110.
The design line ‘very soft clay’ represents soils such as very
soft clays (mud), and loose and weak silts.
In very soft soils the optimum fluke/shank angle is typically 50
deg. The Stevpris Mk5 very soft clay design line is applicable
in soil that can be described by an undrained shear strength
of 4 kPa at the surface increasing by 1.5 kPa per meter depth
or in the equation Su = 4+1.5*z. with Su in kPa and
z being the depth in meters below seabed.
The design line ‘sand’ represents competent soils, such as
medium dense sands and stiff to hard clays.
In sand and hard clay the optimal fluke/shank angle is 32°.
The Stevpris Mk5 design line is based on a silica sand with
a medium density. The medium clay design line represents
soils such as silt and firm to stiff clays. The fluke/shank angle
should be set at 32° for optimal performance.
Performance Statistics
Vryhof Anchors has dedicated more than a generation
to the development, manufacturing and supply of high
holding power anchors. Their anchors are recognized
worldwide as weight for weight the most powerful.
Vryhof anchors are now used in every stretch of the
world’s waters and oil field development areas.
Vryhof Anchors BV
P.O. Box 109
2900 AC Capelle aan den Yssel
The Netherlands
Phone: +31 10 266 8900
Fax:
+31 10 266 8999
E-mail: vryhof@vryhof.com
www.vryhof.com
Copyright © Vryhof Anchors 2010 | Contents subject to change without notice. Vryhof, Stevin, Stevpris, Stevshark, Stevtensioner, Stevmanta and Stevtrack are registered trade marks.
Vryhof reserves all intellectual and industrial property rights such as any and all of their patent, trademark, design, manufacturing, reproduction, use and sales rights thereto and to any article disclosed therein.