NR 542, Sec 1
May 2019 Bureau Veritas 13
1.5 Design life
1.5.1 The requirements about design life, unit modifica-
tions and unit re-assessment are given in Pt A, Ch 1, Sec 1,
[1.7] of the Offshore Rules.
1.6 Station keeping
1.6.1 Permanent installations
Permanent installations covered by the present Note are to
comply with the requirements stipulated in Pt D, Ch 1,
Sec 1, [1.7.1] of the Offshore Rules.
1.6.2 Dynamic positioning system
For units having a mooring system consisting, partly or
entirely, of dynamic positioning system, the Society makes
reference to the requirements given for the additional class
notation DYNAPOS (see Pt A, Ch 1, Sec 2, [6.14.6] of the
Ship Rules).
1.6.3 Mooring to buoy
When the mooring of unit is assured through a floating
buoy, the buoy and its mooring system are to be classed by
the Society.
The buoy is to be considered as a permanent installation
having one of the following service notations:
• gas/condensate loading
• gas/condensate offloading.
The arrangement of the buoy is to comply with the require-
ments of NR494 Rules for the Classification of Offshore
Loading and Offloading Buoys, as applicable.
The additional service feature POSA or POSA-HR is to be
granted to the buoy.
For mooring to an existing Single Point Mooring (SPM) (pos-
sibly classed by another Classification Society), detailed
documentation of the SPM is to be submitted to the Society
for review. This documentation is to include certificate,
design and maintenance. The Society reserves the right to
require complete re-classification of the installation, includ-
ing remeasurement of lines and anchors.
1.7 Scope of additional class notations
1.7.1 Classed topsides - Notations PROC-GP and
PROC-GL
When the additional class notation PROC-GP or PROC-GL
is granted, in addition to requirements given in Sec 13, the
structure of deck modules, flare boom and other structures
housing production equipment, as well as related facilities,
are to be designed and built in accordance with the relevant
requirements of Part B, Chapter 2 and Part B, Chapter 3 of
the Offshore Rules.
When not subjected to green waters, and subject to the
Society agreement, topsides structures may be designed fol-
lowing other recognized standards, provided due consider-
ation is given to inertial loads, overall deformations of the
unit, differential displacements of support points and other
relevant loadings, in accordance with the provisions of
Part B, Chapter 2 of the Offshore Rules.
1.7.2 Notation PROC-GP or PROC-GL not requested
When the additional class notation PROC-GP or PROC-GL
is not requested, the structure of deck modules, flare boom
and other structures housing production equipment are not
covered by the classification.
For equipment and piping installations, where classed sys-
tems within the hull have some part of their facilities
located within the topsides, these facilities are covered by
the classification. The Society reserves the right to include,
in the scope of classification, the structure of the supporting
skid and its connection to the topside structure, even if this
structure is mainly supporting production facilities.
The classification covers the equipment necessary to the
proper operation of these systems, as requested by this Rule
Note and other related applicable rules or standards.
Classification excludes all the equipment only necessary to
the operation of the topsides systems. For these systems,
upon receipt of specific information and request, the Soci-
ety endeavours to verify that failure of equipment and sys-
tems external to the scope of classification does not impair
significantly the hull installation. For the structure support-
ing classed equipment, the attending Surveyor verifies the
proper fitting of the local supporting elements, as indicated
by the equipment manufacturer.
Particular attention is to be paid to the design of the pipe
rack on the main deck, which remains within the scope of
classification, regardless of the presence of pipes serving the
topsides process plants.
Fig 1 and Fig 2 show examples of classification limits for
different types of appurtenances.
1.7.3 Lifting appliances - Notations ALP and ALM
The additional class notations ALP and ALM, as defined in
Offshore Rules Pt A, Ch 1, Sec 2 [8.3.1], may be assigned to
units equipped with cranes and other lifting appliances
meeting the relevant requirements of NR526, Rules for the
Certification of Lifting Appliances onboard Ships and Off-
shore Units.
When no additional class notation for lifting appliances is
granted, the classification covers only the crane pedestal
and its foundation welded to the hull, considering the loads
specified by the designer.
When the crane pedestal and its foundation are welded to a
classed topside structure covered by the additional class
notation PROC-GP or PROC-GL, they are covered by class
for the specific loads provided by the designer.
When one of the additional class notations ALP and ALM is
granted and the crane pedestal is partially or completely
supported by a topside structure not covered by class (addi-
tional class notation PROC-GP or PROC-GL not requested),
the crane pedestal and its foundation are not covered by
class. In case the pedestal is connected to the topside struc-
ture and extended over the hull, only the part of pedestal
connected to the hull is classed for the specific loads pro-
vided by the shipyard.