RECOMMENDED PRACTICE
DNVGL-RP-0232
Edition September 2018
Pipeline and cable laying equipment
The electronic pdf version of this document, available free of charge
from http://www.dnvgl.com, is the officially binding version.
DNV GL AS
FOREWORD
DNV GL recommended practices contain sound engineering practice and guidance.
©
DNV GL AS September 2018
Any comments may be sent by e-mail to rules@dnvgl.com
This service document has been prepared based on available knowledge, technology and/or information at the time of issuance of this
document. The use of this document by others than DNV GL is at the user's sole risk. DNV GL does not accept any liability or responsibility
for loss or damages resulting from any use of this document.
Changes - current
CHANGES – CURRENT
This is a new document.
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Changes – current.................................................................................................. 3
Section 1 General.................................................................................................... 6
1.1 Introduction......................................................................................6
1.2 Objectives......................................................................................... 6
1.3 Scope................................................................................................ 6
1.4 Application........................................................................................ 6
1.5 References........................................................................................ 7
1.6 Definitions and abbreviations........................................................... 8
1.7 Categorization.................................................................................14
1.8 Services.......................................................................................... 15
Section 2 Documentation and certification........................................................... 19
2.1 Documentation to be submitted......................................................19
2.2 Certification requirements.............................................................. 21
Section 3 Material and fabrication........................................................................ 24
3.1 General........................................................................................... 24
3.2 Rolled steel for welding..................................................................24
Section 4 Structural strength................................................................................ 25
4.1 General........................................................................................... 25
4.2 Design loads................................................................................... 25
4.3 Cases of loading............................................................................. 26
4.4 Strength calculations...................................................................... 27
Section 5 Machinery and equipments....................................................................28
5.1 General........................................................................................... 28
5.2 Special requirements for tensioners/drum machines/holding
assemblies/A&R winches/storage equipment...................................... 28
Section 6 Safety and safety equipment.................................................................31
6.1 General........................................................................................... 31
6.2 Safety philosophy........................................................................... 31
6.3 Methods.......................................................................................... 31
Section 7 Testing...................................................................................................33
7.1 General........................................................................................... 33
7.2 System testing................................................................................ 33
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Contents
CONTENTS
7.4 Electrical installations.....................................................................36
7.5 Load test.........................................................................................36
7.6 Periodical surveys...........................................................................36
Changes – historic................................................................................................ 40
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Contents
7.3 Prime movers and fluid power systems.......................................... 36
SECTION 1 GENERAL
1.1 Introduction
The standard for offshore and platform lifting appliance DNVGL-ST-0378 has been successfully used
for pipeline and cable laying equipment. However there are some special considerations for this type of
equipment that are not covered in detail in DNVGL-ST-0378, particularly with respect to the definition of
safe working load and of the relevant load cases, safety systems and testing for pipeline and cable laying
equipment. This recommended practice addresses the specific needs for pipeline and cable laying equipment
and is based on the initial results from the joint industry project Development of codes for offshore cable and
pipe laying equipment. This recommened practice will therefore be supplementary to the DNVGL-ST-0378.
1.2 Objectives
The objective of this recommended practice is to provide criteria and guidance for certification and
verification of the design, materials, fabrication, safety, testing of the pipeline and cable laying equipment
and systems.
These specifications have been developed with the view of promoting safety by providing industry unified
criteria for verification and certification of the pipeline and cable laying systems. It can therefore serve as a
technical guidance for manufacturers seeking verification or certification of equipment and systems used for
pipeline and cable laying, retrieving, handling repair operations and handling maintenance operations.
In summary, the objectives of this recommended practice are to:
— provide an internationally acceptable recommended practice of safety for pipeline and cable laying
equipment and systems by defining minimum requirements for the design, materials, fabrication,
installation and testing
— serve as a technical reference document in contractual matters between purchaser and contractor
— serve as a technical reference document for classification, certification and verification services
— serve as a guideline for designers, purchasers and contractors.
1.3 Scope
These guidelines and specifications cover the equipment associated with pipeline and cable laying operations,
regardless of the laying method (J lay, S lay, Flex lay, Reel Lay, etc. ). The laying operations cover the
spectrum of operations from load-out, transportation and pipeline and cable handling to laying or retrieving,
recovery and repair.
1.4 Application
This document provides general requirements to reach the objectives as listed in [1.2].
This recommended practice is applicable for certification of pipeline and cable laying equipment. For DNV GL
classification purposes, these vessels are identified by the class notation Pipe laying vessel or Cable laying
vessel.
This recommended practice may also be applied on a voluntary basis for verification or certification of
pipeline and cable laying equipment temporarily or permanently installed on any other supporting vessels.
Figure 1-1 illustrates the workflow from project initiation to testing of equipment, with corresponding sections
in this document.
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Figure 1-1 Use of this recommended practice
1.5 References
Only the latest revision of the following referenced standard at the time this document is applied shall be
used.
Table 1-1 Rules and standards for certification
Document code
Title
DNVGL-RU-SHIP
DNV GL Rules for classification: Ships
DNVGL-ST-0378
Standard for offshore and platform lifting appliances
Table 1-2 Class programmes
Document code
Title
DNVGL-CG-0156
Conversions of ships
DNVGL-CG-0197
Additive manufacturing - qualification and certification
process for materials and components
DNVGL-CP-0337
General description of services for certification of materials
and components
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Document code
Title
DNVGL-CP-0338
Type approval scheme
Table 1-3 Other normative references
Document code
Title
ISO 10474
Steel and steel products - Inspection documents
ISO 12482
Cranes - Monitoring for crane design working period
EN 10204
Metallic products - Types of inspection documents
1.6 Definitions and abbreviations
1.6.1 Abbreviations
Table 1-4 Abbreviations
Abbreviation
Description
AP
approved
A&R
abandonment and recovery
FI
for information
FMEA
failure modes and effects analysis
HAZID
hazard identification analysis
HAZOP
hazard and operability study
ILO
International Labour Organization
MBR
minimum bending radius
MELL
maximum exceptional line load (specific to active and
passive equipment, see [1.7])
MOLL
maximum operational line load (specific to active and
passive equipment, see [1.7])
MSL
maximum storage load (specific to storage equipment, see
[1.7])
OLA
test certificate for test and thorough examination of Lifting
apliances (non-ILO)
PC
product certificate
PLET
pipeline end termination
QRA
quantitative risk analysis
TA
type approval
TD
design temperature
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Abbreviation
Description
TR
test report
1.6.2 Definitions
Table 1-5 Definitions
Term
Definition
abandonment & recovery
operation of abandoning and recovering the pipeline or
cable to and from the seabed
abandonment & recovery system
system whose primary function is to lower and retrieve the
product to and from the seabed
aligner
radius controller typically located at the top of a laying
tower
Used to maintain a minimum radius and guide the product
from inboard storage devices into the firing line by
changing its direction and accommodating differences in
alignment. The Aligner is usually a larger diameter wheel,
series of rollers in an arc, on a belt in an arc.
chute
equipment used for guiding the product during laying
operations
Typically used in horizontal lay systems to help overboard
the product and avoid bending less than the MBR in one or
two planes. May be called an overboarding chute.
carousel/basket
equipment used for storage during transportation and
installation of flexible pipelines, umbilicals, cables and other
products for offshore applications
The carousel's purpose is storing the product around a
central vertical core. The product is arranged in horizontal
or vertical layers around the central core from the base
upwards.
clamp (friction)
equipment used to hold the product during laying
operations
The friction clamp consists of a series of pads aligned
around the circumference of the product. The friction clamp
working principle is based on generating grip between the
clamp pads and the product, and thus holding the product
(similar to the tensioner, however it has no paying out/in
capabilities).
collar clamp (hang-off)
equipment used to hold the product during laying
operations
Unlike friction clamps, hang-off collar clamps working
principle is providing support to the product (product is
hanging off from the clamp by means of a collar/flange
which rests on the body of the hang-off clamp).
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Term
Definition
dead loads
weights of all the fixed and mobile components of
equipment associated with laying operations and loose gear
permanently present during operation
For the purpose of marking, the dead loads of loose gear
are designated as weight by the ILO. The unit is specified in
tons (t) or kilograms (kg).
deflector
equipment used for guiding the product during laying
operations
Typically used in flexible lay systems to help avoid bending
less than the MBR in one or two planes.
design temperature
reference temperature used as a criterion for the selection
of steel grades
The design temperature TD for pipeline and cable laying
equipment is defined as the lowest acceptable service
temperature for the equipment.
drum machines (capstan)
machine consisting of a rotating drum used to hold and
control the product line load
The capstan working principle is based on friction build-up
between the drum and the product line.
emergency laying operations
operation of assembling and laying the pipeline and cable
on the seabed, from start-up point to lay-down point,
during emergency conditions
gripping force
product holding force generated by the squeeze force and
dependent on the friction between the product and the
squeezing assembly
holding assemblies
friction clamps, hang-off clamps or Chinese fingers
inertia forces
forces induced by change of linear or angular velocity
inspection certificate 3.1
document issued by the manufacturer which contains the
results of all the required tests
It shall certify that the tests have been carried out by
the manufacturer on samples taken from the delivered
products direct. See EN 10204 and ISO 10474.
loading arm
equipment consisting of a support structure/frame/
tower, positioning mechanism, component for controlling
and holding the product line and passive guides/radius
controllers
Used for loading or unloading flexible product to and from a
storage device.
machinery components
rotating components transferring torque for driving/braking
purpose
Examples ar gearboxes, wheels and shafts.
maximum dynamic braking load
maximum line load that it is developed during the stopping
in the minimum stopping time (emergency-stop time) the
product line moving at maximum speed while loaded with
MOLL or MELL as requested
It is associated with structural strength SF= 1.0.
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Term
Definition
maximum exceptional line load (MELL)
maximum emergency dynamic line load, which may be
determined considering the selfweight of the product line
and the hydrodynamic effects acting on it (wave, current,
drag, added mass, etc), inertia, product line stiffness,
vessel movement and the catenary shape solution
It is assumed that MELL is determined following an
installation analysis and it shall be provided by the
designer. MELL is defined as the equipment rating during
emergency conditions (eg. operation outside design
weather window, emergency/accidental A&R operations).
maximum line speed
maximum line speed at which the equipment can safely
work as per equipment design specification
maximum operational line load (MOLL)
maximum operational dynamic line load, which may be
determined considering the selfweight of the product line
and the hydrodynamic effects acting on it (wave, current,
drag, added mass, etc), inertia, product line stiffness,
vessel movement and the catenary shape solution
It is assumed that MOLL is determined following an
installation analysis and it shall be provided by the
designer. MOLL is defined as the equipment rating during
normal operation.
minimum bending radius (MBR)
minimum allowable bend radius as defined by the product
manufacturers
maximum storage load (MSL)
maximum payload stored in the storage equipment, see
Table 1-7
minimum stopping time (quick stop time)
minimum time required for the parking brake to stop the
product line considering maximum laying speed
normal laying operation
operation of assembling and laying the pipeline and cable
on the seabed, from start-up point to lay-down point,
during normal operation conditions
offshore operation
variety of offshore operations covering a spectrum of
operations from load-out, transportation and pipeline and
cable handling to laying or retrieving, recovery, repair and
maintenance
pipeline and cable laying equipment
structural/mechanical assemblies (individual equipment)
with functionality during pipeline and cable laying and/or
retrieving and or handling maintenance and/or handling
repair operations
pipeline and cable laying control system
system which controls and monitors the functionality of the
installation spread or the individual equipment, may also
include the safety system
pipeline and cable laying system (installation spread)
equipment necessary to perform the pipeline and cable
laying and/or retrieving and/or handling maintenance and/
or handling repair operations
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Term
Definition
essential system consisting of a series of sub-systems an
performing a series of essential functions (i.e. essential
safety functions) preventing the use of the equipment
outside its operational limitations (e.g. overload systems,
etc.)
pipeline and cable laying safety system
compliance document validated and signed by the issuing
organization:
— identifying the product that the certificate applies to
— confirming compliance with referred requirements.
It is required that:
product certificate (general)
— the tests and inspections have been performed on the
certified product itself, or, on samples taken from the
certified product itself
— the tests were witnessed by a qualified representative
of the organization issuing the certificate, or, his
authorized representative.
a compliance document validated and signed by the issuing
organization and DNV GL's representative:
— identifying the product that the certificate applies to
— confirming compliance with referred requirements.
It is required that:
product certificate (DNV GL's)
— the tests and inspections have been performed on the
certified product itself, or on samples taken from the
certified product itself
— the tests were witnessed by a qualified representative
of the organization issuing the certificate and DNV
GL's representative, or in accordance with special
agreements.
product
the main object to be installed, i.e. rigid pipeline, flexible
pipe, umbilical or power cable
product line
continuous string of product between storage device and
seabed including intermediate and ancillary pieces e.g. end
terminations, clamps, etc
quadrant
equipment used during handling of product line used to
ensure keeping the product within allowable strain limits
The structure is normally loose and it's lifted by a crane
during handling operations.
pipeline end termination (PLET) handling equipment
equipment used to handle the pipeline end termination
radius controller
equipment used to maintain a minimum bending radius
(MBR) of the product, whilst changing its direction
The product is generally supported by a continuous surface
or series of rollers.
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Term
Definition
reel
equipment used for storage during transportation and
installation of flexible pipe, umbilicals, risers and other
products for offshore applications
The reel principle is based on storing the product around a
central horizontal core.
reel drive system
system used for spooling and unspooling of rigid and
flexible pipe, umbilicals, risers and other products for
offshore applications, stored on multiple reels
ship type notations
code used by the classification societies to define a type of
vessel related to its most typical service
(Cable Laying vessel, pipe laying vessel, passenger ship
and crane vessel are typical examples).
squeeze force
force normal to product surface, applied to generate griping
force
stinger
equipment used to support the product at the exit point
from the vessel, and ensures keeping the product within
allowable strain limits
The structure is normally pinned/hinged to the hull
structure of the host vessel.
storage winch
part of the A&R system, it works in combination with the
traction winch
Its purpose is storing the wire rope and maintaining a
constant hold-back force for the traction winch. It has low
load capabilities, relative to the traction winch.
straightener
mechanism used to apply a reverse bending moment and
restore the straightness of rigid linel
equipment used to grip, control the movement and/or
hold the product line in its axial direction, by applying a
squeezing force on the product
Tensioner normally consists of several caterpillartype tracks mounted in a frame or multiple wheel pair
device made up of vertically opposed rubber tires which
hydraulically close down on the product.
tensioner
The tensioner working principle is based on generating grip
developed between the caterpillar-type tracks or the wheel
pairs and the product, and thus controlling and holding
the product. The grip force is independent of product line
tension.
Tensioners are normally required to operate over a range of
product types and diameters.
document signed by the manufacturer stating:
— conformity with requirements given by a relevant
standard
test report
— that tests are carried out on samples from the current
production
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Term
Definition
traction winch
winch part of the A&R system, usually consisting of two
drums
The traction winch working principle is based on friction
build-up between the drums and the wire rope.
travelling assembly
structural and mechanical component used to support the
clamps which travel along a predefined guided path along
the laying tower height
type approval
approval of conformity with specified requirements on the
basis of systematic examination of one or more specimens
of a product representative of the production, see DNVGLCP-0338
document signed by the manufacturer stating:
- conformity with rule requirements
- that tests are carried out on the certified product itself
- that tests are made on samples taken from the certified
product itself
works product certificate
- that tests are witnessed and signed by a qualified
department of the manufacturers,
see DNVGL-RU-SHIP Pt.1 Ch.3 Sec.5
1.6.3 Verbal forms
Table 1-6 Definition of verbal forms
Term
Definition
may
verbal form used to indicate a course of action permissible within the limits of the document
shall
verbal form used to indicate requirements strictly to be followed in order to conform to the document
should
verbal form used to indicate that among several possibilities one is recommended as particularly suitable,
without mentioning or excluding others, or that a certain course of action is preferred but not necessarily
required
1.7 Categorization
Generally, the pipeline and cable laying systems components are categorized as follows.
Depending on the system configuration, the below defined categories for various equipment shall be agreed
with DNV GL on a case-by-case consideration.
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Table 1-7 Categorization
Type
Description
Active equipment - high risk
Equipment used to control and suspend the product line
(e.g. tensioner, drum machines, friction and hang-off
clamp, travelling assembly, A&R system, etc. and their
supporting structure), whose failure to perform its function
is associated with significant risk to product line, property
other than product (equipment and host asset), life or
environment (i.e. failure in these equipment could lead to
loss of load).
Active equipment - low risk
Equipment used to control and suspend the product line
whose failure to perform its function is associated with
low risks for product line, property other than product
(equipment and host asset), life or environment (i.e.
failure in these equipment will not lead to loss of load).
Normally these are all the rest of the equipment other than
the "active equipment - high risk" involved in the various
phases of the pipeline laying or retrieving operation (e.g.
service crane, reeving assemblies inboard of tensioner/
hang-off clamp, initiation winch and other winches,
spooling equipment PLET handling equipment, etc.).
Passive equipment
Equipment used to alter the direction or guide the product
(radius controller, centralizer, straightener, stinger, chute,
deflector, quadrant, etc).
Storage equipment
Equipment used to store the product (storage winch,
carousels, reels, etc.).
1.8 Services
1.8.1 General
The following activities are covered by this recommended practice:
Basic certification:
— design review (approval), see [1.8.2]
— survey during fabrication and installation, see [1.8.3]
— witness testing and marking, see [1.8.6].
Verification
— design review (verification), see [1.8.4], [1.8.5] and [1.8.7.2].
Figure 1-2 describes the services offered and the associated documents issued by DNV GL to prove
compliance.
Guidance note:
Individual equipment, part of an installation spread, can be certified provided it is clearly defined whether it can function as
standalone or as integrated equipment. If the latter is applicable, then the integration with the rest of the installation spread
and control system should be considered by the responsible entity for the delivery of the pipeline and cable laying systems. For
definitions see Table 1-5.
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Figure 1-2 Alternatives for documentation that may be issued to customers depending on type
and combination of services requested.
1.8.2 Design review procedure
Load-carrying and other important components of a pipeline and cable laying system are subject to design
review with respect to strength and suitability for its purpose. A design approval is granted when the design
review has been concluded without any non-compliances.
The design review may be substituted, partly or completely, by enhanced manufacturing survey and/or
testing. In cases where the substitutions are applied for by the customer, agreements shall be made between
the customer and DNV GL regarding possible reductions of documentation to be submitted for approval/
information.
Upon special agreement, the design review may be substituted by a strength evaluation based upon testing
until failure.
Structural strength review of the components related to power supply and safety equipment is normally not
carried out by DNV GL.
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1.8.3 Survey during manufacturing and installation
Normally, a survey during manufacture of each separate pipeline and cable equipment shall be carried out by
DNV GL's surveyor in order to ascertain compliance with the approved drawings, other requirements given in
this recommended practice as well as general good workmanship.
As an alternative to survey during manufacture of each separate equipment, modified survey procedures and
survey arrangements may be accepted, see DNVGL-CP-0337.
After an equipment or installation spread has been installed on its permanent foundation in preparation for
function testing, and before testing can take place, it shall be subjected to a survey by DNV GL.
1.8.4 Extension of scope of work
Upon request from the customer, the scope of work may be extended beyond the subjects and aspects
covered in this certification standard. Extensions shall be agreed in writing. DNV GL may, if found necessary,
require that the customer presents reference documents for the extended scope of work, such as authority
regulations, norms and standards.
In case of disputes regarding interpretations of requirements on which extended work is based, the
customer shall contact the publisher/owner of the requirements and obtain their written interpretation. If the
publisher/owner is not willing to interpret the disputed requirement, or an interpretation for other reasons
cannot be acquired, DNV GL's interpretation will prevail.
1.8.5 Limitation of scope of work
Upon request from and agreed with the customer, parts of the scope of work, components, systems or
specific aspects or requirements may be excluded from the scope of work specified in this certification
standard. This will be annotated in the documentary evidence of the completed assignment.
DNV GL will not agree to limit the scope of work or parts of the suggested services if they are of the opinion
that this may lead to hazards or unacceptable lowering of the safety standard.
A limitation of scope of work is not applicable when a DNV GL product certificate is required.
1.8.6 Testing
Equipment and installation spreads shall be subjected to functional testing and load testing as specified in
Sec.7.
1.8.7 Types of services
1.8.7.1 Basic Certification
Pipeline and cable laying equipment and systems found to comply with these basic requirements are qualified
for DNV GL's product certification, whereupon the product certificate Form 71.03a may be issued based on
FAT (factory acceptance test) and survey. Following successful testing and survey after installation onboard, a
DNV GL Product certificate will be issued for pipeline and cable laying system. This basic requirement covers
both individual pipeline and cable laying equipment and installation spread, see Table 1-5.
For equipment not part of class, the certification may be concluded at the manufacturer, based on FAT and
survey. On-board test procedures as well as witness/acceptance may be endorsed by a competent person
accepted by flag/state authorities.
1.8.7.2 Verification
DNV GL may upon request carry out specified examination or combination of separate services referring to
the requirements given in Sec.3 through Sec.7 or the related standards and services described in [1.8].
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The depth, thoroughness and completeness of the examinations shall be agreed upon for each specific
verification assignment, and shall be unambiguously described in the contract and in the documentation of
the verification service.
Guidance note:
DNV GL is flexible in agreeing on type of documentation of verification services performed. Normally, DNV GL’s proposal will be to
issue a verification report. For instance, for a completed design examination DNV GL will suggest issuance of a Design verification
report.
DNV GL endeavours to find the best solution for issuance of required verification documentation.
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Whereas the scope, standards and acceptance criteria for a certification or classification assignment is
laid down by DNV GL, the scope, standards and acceptance criteria forming the basis for a verification
assignment may, if requested, be adapted to the needs and desires of the customer. However, DNV GL will
decline to carry out a commission that may be used, intentionally or unintentionally, to mislead a third party
with regard to the safety of the object.
A verification report may be edited in accordance with the customer’s needs and requests. DNV GL is,
however, not prepared to omit non-conformities or other negative observations or results detected during the
examinations.
1.8.7.3 Pipeline and cable laying systems included in class scope
DNV GL certified pipeline and cable laying equipment and systems installed on board vessels and offshore
units classed with DNV GL may be included in the scope of work covered by classification. In such cases
the vessel/offshore unit will be assigned the additional class notation Pipe laying vessel or Cable laying
vessel.
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SECTION 2 DOCUMENTATION AND CERTIFICATION
2.1 Documentation to be submitted
The documentation requirements stated below in Table 2-1 are required for design approval and ensuing
certification.
Table 2-1 Documentation requirements
Object
Document
type
Active
Equipment
- high risk
Installation spread
Active
Equipment
- low risk
Passive
equipment
Storage
equipment
C010 - Design
Criteria
FI
FI
FI
FI
FI
C020 Assembly or
arrangement
drawings
FI
FI
FI
FI
FI
C030 Detailed
drawing
AP
AP
AP
AP
AP
C040 - Design
analysis
FI
FI
FI
FI
FI
C050 - Nondestructive
testing (NDT)
plan
AP
AP
FI
FI
FI
Z060 Functional
description
FI
FI
FI
FI
FI
Z252 - Test
procedure at
manufacturer
AP
AP
FI
FI
FI
Z253 - Test
procedure for
quay and sea
trial
AP
AP
FI
FI
FI
Z161 Operational
manual
FI
FI
FI
FI
FI
Power supply
A030 - System
arrangement
plan
FI
FI
FI
FI
FI
Electrical
power system
E170 Electrical
schematic
drawing
AP
AP
FI
FI
FI
General
1)
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Document
type
Object
Active
Equipment
- high risk
Installation spread
Z090 Equipment list
FI
A011 - System
diagram
(P&ID)
AP
S042 Hydraulic
control
diagram
AP
Z060 Functional
description
Active
Equipment
- low risk
Passive
equipment
Storage
equipment
FI
FI
FI
FI
1)
AP
FI
FI
FI
1)
AP
FI
FI
FI
FI
FI
FI
FI
FI
Z090 Equipment list
FI
FI
FI
FI
FI
Control and
monitoring
I200 Control and
monitoring
system
documentation
AP
1)
AP
FI
FI
FI
Fire safety
G090 - Area
safety chart or
fire protection
data chart
AP
1)
AP
FI
FI
FI
Failure mode
and effect
analysis
Z071 - Failure
mode and
effect analysis
(FMEA)
FI
-
-
-
-
Quantitative
risk analysis
Quantitative
risk analysis
(QRA)
AP
Hydraulic
power system
2)
2)
AP = for approval, FI = for information
1) If the installation spread is subject to certification, the general assembly drawings/documentation shall be submitted,
and not detailed drawings/documentation for each equipment.
2) See also Sec.6.
Guidance note:
Considering the type service requested (full scope certification see [1.8.7.1] or reduced scope see [1.8.7.2] the requirements for
documentation will be accordingly adjusted. Examples below:
1)
The documentation required for structural design verification in [1.8.5.3] may be limited to “General” object, see Table 2-1.
2)
The documentation required for certification in [1.8.5.1] (complete review, including structural review and control system
review) extends to the complete list provided in Table 2-1.
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2.2 Certification requirements
The certification requirements stated in Table 2-2 below are required for ensuing certification of installation
spreads. The certification requirements stated in Table 2-3 to Table 2-6 below are required for ensuing
certification of pipeline and cable laying equipment.
Table 2-2 Certification requirements - installation spread
Object
Certificate type
Active equipment - high risk
PC
Active equipment - low risk
PC
Passive equipment
PC
Storage
PC
Table 2-3 Certification requirements - active equipment - high risk
Object
Certificate type
Issued by
Additional description
Slewing rings
PC
DNV GL
Hydraulic cylinders
PC
DNV GL
Winches
PC
DNV GL
Sheaves
PC
DNV GL
works product certificate will
be satisfactory for unwelded
metallic sheaves
Tensioner track
PC
Manufacturer
design approval and works
product certificate
Track chain
PC
Manufacturer
Track pads
-
applicable also for
accumulators
-
designer and client/owner/
operator shall agree the
performance requirements
for the track pads
Wire rope
PC
DNV GL
certificate of test and
thorough examination
of loose gear (CG4)
Alternatively ILO form No.4.
Transmission gears, screw
jacks and brakes
PC
Manufacturer
design approval and works
product certificate
Slewing gear
PC
Manufacturer
works product certificate
Hydraulic components
TR
Manufacturer
Electrical motors with rating
100kW and above
PC or TA
DNV GL
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applicable for class notation
only
Page 21
Object
Certificate type
Issued by
Additional description
Motor starters and frequency
converters with rating
PC or TA
100kW and above
DNV GL
applicable for class notation
only
Control&monitoring system
PC
DNV GL
applicable for class notation
only
Slip rings, with rating 100
kW and above
PC
DNV GL
applicable for class notation
only
PC = product certificate, TA = type approval, TR = test report
Table 2-4 Certification requirements - active equipment - low risk
Object
Certificate type
Issued by
Additional description
Service crane
PC
DNV GL
category - platform crane
Slewing rings
PC
Manufacturer
when not installed on the
service crane
Hydraulic cylinders
PC
DNV GL
Applicable also for
accumulators
Winches
PC
DNV GL
Sheaves
PC
DNV GL
works product certificate will
be satisfactory for unwelded
metallic sheaves
Tensioner track
PC
Manufacturer
design approval and works
product certificate
Track chain
PC
Manufacturer
Wire rope
PC
DNV GL
certificate of test and
thorough examination
of loose gear (CG4).
Alternatively ILO form No.4
Transmission gears, screw
jacks and brakes
PC
Manufacturer
design approval and works
product certificate
Slewing gear
PC
Manufacturer
works product certificate
Hydraulic components
TR
Manufacturer
except mountings
PC = product certificate, TA =type approval, TR = test report
Table 2-5 Certification requirements - passive equipment
Object
Certificate type
Issued by
Hydraulic cylinders
PC
Manufacturer
Transmission gears, screw
jacks and brakes
PC
Manufacturer
Hydraulic components
TR
Manufacturer
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Additional description
Page 22
Object
Certificate type
Issued by
Additional description
Issued by
Additional description
PC = product certificate, TA = type approval, TR = test report
Table 2-6 Certification requirements - storage equipment
Object
Certificate type
Slewing rings and bearings
PC
Manufacturer
Transmission gears, screw
jacks and brakes
PC
Manufacturer
works product certificate
Slewing gear
PC
Manufacturer
works product certificate
Hydraulic components
TR
Manufacturer
except mountings
PC = product certificate, TA = type approval, TR = test report
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Page 23
SECTION 3 MATERIAL AND FABRICATION
3.1 General
Generally, the material and fabrication requirements listed in DNVGL-ST-0378 are valid for pipeline and cable
laying systems. This section specifies requirements specific to pipe and cable laying systems which replace
those listed in the aforementioned sections.
The use of materials, products and components made by additive manufacturing technologies (defined as
manufacturing processes involving sequential layer material addition throughout a 3D work envelope under
automated control) shall be subject to approval and qualification according DNVGL-CG-0197 on a case by
case basis. The designer shall preventively inform DNV GL about the intended use of additive manufacturing
components during the production/assembly process.
3.2 Rolled steel for welding
Required impact test temperatures are dependent on design temperature (see Table 1-5) and the material
thickness. Impact test temperatures for structural steel for special, primary and secondary applications are
given in Table 3-1 which replace the requirements listed in DNVGL-ST-0378 Table 3-1.
Table 3-1 Impact properties for welded structural steel
1)
Impact test temperatures in °C
Material thickness t in mm
6 ≤ t ≤ 12
3)
Structural steel for special
2)
and primary members
Structural steel for
2)
secondary members
T
D
+ 20
Test not required
12 ≤ t ≤ 25
T
D
+ 10
Test not required
25 ≤ t ≤ 50
T
D
- 10
t > 50
T
D
- 30
T
D
+ 10
T
D
1) For steel with yield stress below 500 MPa, the test temperature need not be taken lower than -40°C. For steel with
yield stress above 500 MPa, the test temperature shall not be taken higher than 0°C and not lower than -60°C.
2) See Table 1-5 for definitions.
3) For plate less than 6 mm, Charpy V testing will not be required.
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Page 24
SECTION 4 STRUCTURAL STRENGTH
4.1 General
Generally the load definitions listed in DNVGL-ST-0378 Sec.4 are valid for pipeline and cable laying
equipment. This section provides requirements specific to pipeline and cable equipment which replace those
listed in the aforementioned standard.
4.2 Design loads
4.2.1 Principal loads
The principal loads are:
— The loads due to dead weight of the components (SG).
— The loads due to maximum operational line load (MOLL). The maximum operational line load is considered
to be of continuous dynamic nature; to be defined by the designe.
— The loads due to maximum storage load (MSL). For storage equipment the maximum operational load is
considered the maximum selfweight of the product, in addition to any relevant line tension.
The horizontal components due the heel and trim of the vessel, shall be taken into account. The values to be
considered are the maximum angles expected during laying or retrieving operation with no wind and waves
acting. If not otherwise specified by the designer, minimum values to be used, are given in Table 4-1.
Table 4-1 Minimum heel and trim angles, still water
Type of vessel
Heel
Trim
Ships and vessels having ship-shape
hull properties
Min. 5°
Min 2°
Barges of length less than 4 times
breadth, and catamarans
Min. 3°
Min 2°
Semi-submersibles
Min. 3°
Min. 3°
Significant inertia forces induced due to the change of velocity in the product line shall be considered.
The inertia due to angular acceleration/deceleration of rotating machinery components shall be taken into
account when this effect is significant.
4.2.2 Loads due to motion of the vessel
1)
2)
3)
For normal laying, retrieving and maintenance operations, the inertia forces due to ship motion shall be
calculated. The vessel accelerations for the operational cases shall be stated by the designer (SMop).
For emergency laying, abandonment and retrieving operations, the inertia forces due to ship motion shall
be calculated. The vessel accelerations for the emergency cases shall be stated by the designer (SMEm).
For transit conditions the inertia forces due to ship motion shall be calculated. The vessel accelerations
for the transit/survival case shall be based on the extreme values given in the governing code for the
supporting vessel (SM).
The inertia forces caused by the vessel motions shall be combined according to relevant rules/calculations for
the vessel considered.
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4.2.3 Loads due to climatic effects
4.2.3.1 Loads due to wind
Loads due to wind shall be calculated in accordance with DNVGL-ST-0378 App.A or a recognized code or
standard:
1)
2)
3)
Loading due to working wind (SW).
Loading due to emergency wind (SEm). For emergency laying, abandonment and retrieving operations,
the wind forces shall be stated by the designer.
Loading due to out of service wind (SWmax).
4.2.3.2 Loads due to ice and snow
Snow and ice loads may be neglected in the design calculations except for equipment working under
exceptional conditions, or for equipment of special design being particularly sensitive to such effects.
4.2.3.3 Loads due to sea pressure
These loads will vary according to vessel type and the actual location of the equipment on vessel.
Sea pressure loads shall be calculated according to DNVGL-RU-SHIP Pt.3 Ch.4 Sec.5 and DNVGL-CG-0156.
4.2.3.4 Air temperature
Unles otherwise specified in this recommended practice, systems and equipment shall be designed for
operation under ambient air temperature:
— between the minimum design temperature and 45°C
— inside machinery housing or other compartments containing equipment between 5°C and 55°C .
4.3 Cases of loading
4.3.1 Introduction
For the purpose of making the nominal safety dependent upon the probability of occurrence of the loading,
three general cases of loading are defined, for which the required safety margins are different:
Case I
Case II
= pipeline and cable laying equipment subject to normal working conditions
= pipeline and cable laying equipment subject to emergency operational loading
conditions
Case IIIa and IIIb = pipeline and cable laying equipment subject to transit/survival and accidental loading
conditions.
4.3.2 Case I: Pipeline and cable laying systems subject to operational
loading
This load case includes the loads that will occur under normal laying operations.
Guidance note:
Due to the complex nature of the operations, during the different phases of laying (initiation, laying/retrieving, abandonment,
etc.), the loading scenario/main load path is subject to change. This implies that the various components of the system (individual
equipment) will become active or on standby, depending on the phases of operation. Therefore, each component, as well as the
pipeline or cable laying system assembly should be designed considering the most onerous relevant load combinations.
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Defined by symbols listed above and in [4.2.1], the following load combinations shall be considered in load
case I:
SG + MOLL + MSL (as applicable)+ SMop + SW
Guidance note:
For the equipment to which MOL or MSL is not the direct load, then the loading associated with normal operational loading should
be applied in the above formula.
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4.3.3 Case II: Pipeline and cable laying systems subject to emergency
operational loading
This load case includes the loads that will occur during laying operations, generally associated with moderate
(low to medium) probability level of occurrence. This is to be acknowledged as an intermediate load case,
between normal operation and accidental conditions. Applicability of this case shall be agreed on a case by
case basis.
SG + MELL + MSL (as applicable) + SMEm + SWEm
Guidance note:
Generally, this load case includes loads that will occur during weather escalation or increased line load as a result of an accident
(i.e. pipe flooding). The equipment could be designed to maintain its functionality, possibly with reduced parameters, when laying
in higher seastates than normal operation weather window or with higher line load. These conditions would generally be considered
undesirable and, therefore, having much lower probability of occurrence than normal operation.
The loads should be agreed between the designer and client/owner/operator.
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4.3.4 Case IIIa: Pipeline and cable laying systems subject to transit
This case is defined as:
SG + MSL (or relevant load during transit) + SM + SWmax
Guidance note:
The active or passive equipment will normally not be in operation during transit conditions. Therefore the formula above should be
applied without MSL (since this is not applicable for active or passive equipment).
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4.3.5 Case IIIb: Pipeline and cable laying systems subject to accidental
loads
Accidental loads, which are defined as load with low probability of occurrence in accordance with relevant
product installation code, are generally associated with accidental loads in the product line and degraded
mode of equipment. These shall be identified by the designer and evaluated on a case-by-case basis.
The loads shall be agreed between the designer and client/owner/operator.
4.4 Strength calculations
The strength calculations shall follow the requirements listed in DNVGL-ST-0378 [4.3] with respect to
excessive yielding, buckling and fatigue fracture.
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DNV GL AS
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SECTION 5 MACHINERY AND EQUIPMENTS
5.1 General
Generally the requirements listed in DNVGL-ST-0378 Sec.5 are valid for pipeline and cable laying systems
with the following additions.
5.2 Special requirements for tensioners/drum machines/holding
assemblies/A&R winches/storage equipment
5.2.1 Tensioners
5.2.1.1 Brake redundancy philosophy and capacity
The tensioner brakes shall be dimensioned considering:
— The holding capacity for tensioners shall be dimensioned based on the greater between the maximum
operational line load (MOLL) and maximum exceptional line load (MELL), see Table 1-5, as applicable.
— The equipment shall be designed to be fail safe with respect to braking and holding capacity (i.e. such
that any single failure shall not lead to loss of holding and braking capacity (eg. failure of a squeezing
component, failure in a braking component, etc.). The equipment shall be capable of holding and braking
the operational load while in a degraded mode (while one of the components of the holding or braking
assembly has lost its functionality and capacity). Component reliability study shall be performed to
support the system design solution with respect to redundancy and to confirm that the above criteria is
met. This paragraph replaces the requirement for brakes redundancy listed in DNVGL-ST-0378 [8.4.2.13].
Guidance note:
When a discreet equipment, part of an installation spread, is subject to approval and/or certification by DNV GL, the equipment's
redundancy philosophy shshould be subject to review. The redundancy will be clearly listed in the design approval letter and/or
product certificate as equipment operational limitation.
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— For the equipment relying on squeezing force for the generation of gripping force, see Table 1-5, the
squeezing arrangements shall be designed for the maximum squeezing force, corresponding to Case I
loading, see [4.3].
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Guidance note:
The structural strength of the tensioners, holding assemblies and the brake foundation is understood different to the brakes
capacity. Capacity rating corresponds to the brake ultimate frictional capacity. The structural strength assessment should be based
on the corresponding case of loading. E.g.:
—
If the MOLL is the dimensioning load, then the structural strength of the assembly should be based on MOLL and acceptance
criteria for case I.
—
If the MELL is the dimensioning load, then the structural strength of the assembly should be based on MELL and acceptance
criteria for case II or III, as applicable, see [4.3].
—
If the maximum dynamic braking load is the dimensioning load, and this is considered as exceptional load and acceptance criteria
for case III .
Unless otherwise specified by the manufacture considering the safety operation philosophy, minimum values listed in Table 5-1
apply.
Table 5-1 Tensioner brake capacity requirement
Case of loading -
Load due to
Brake capacity
structural strength
MOLL
I
II/III
MELL
as applicable, see [4.3]
2)
Dynamic braking due to MOLL
2)
Dynamic braking due to MELL
III
III
Hydraulic restriction
capacity (if used as a brake)
1.5 × MOLL
1.5 × MOLL
1.33/1.1 × MELL
1.33/1.1 × MELL
1.0 × maximum dynamic
1.0 × maximum dynamic
braking load
braking load
1)
1)
1.0 × maximum dynamic
1.0 × maximum dynamic
braking load
braking load
1)
1)
The dynamic braking capacity should be based on corresponding dynamic friction coefficient.
2)
If considered applicable.
1)
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5.2.1.2 Hydraulic restriction as brake
Hydraulic restriction may be acceptable as brake, considering the following conditions are proven:
— brake engagement/disengagement time shall be adequate to the intended application, with due
consideration for mitigating the risks associated with lack of braking capacity or overload of the system,
see DNVGL-ST-0378 [8.4.2.13] and DNVGL-ST-0378 [8.4.2.4], respectively.
— the hydraulic motor shall have a closing valve directly at the high-pressure (load) connection (no pipe or
hose connection in between).
— the closing valve shall close as a result of pressure loss at the low-pressure connection (inlet connection
during lowering). This function shall be accomplished by direct bore or piping between the closing valve
and the low-pressure connection.
— the hydraulic motor shall always be ensured sufficient working fluid, also in the event of power failure, i.e.
gravity feeding.
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5.2.2 Drum machines
The drum machines brakes shall be dimensioned considering:
— The holding capacity for drum machines shall be dimensioned based on the greater between the
maximum operational line load and maximum exceptional line load, see Table 1-5, as applicable.
— The equipment shall be designed to be fail safe with respect to braking and holding capacity (i.e. such
that any single failure shall not lead to loss of holding and braking capacity (eg. failure in a transmission
or a braking component, etc.). The equipment shall be capable of holding and braking the operational load
while in a degraded mode (while one of the components of the holding or braking assembly has lost its
functionality and capacity). Component reliability study shall be performed to support the system design
solution with respect to redundancy and to confirm that the above criteria is met. This paragraph replaces
the requirement for breaks redundancy listed in DNVGL-ST-0378 [8.4.2.13].
5.2.3 Holding assemblies
The holding capacity for holding assemblies shall be dimensioned based on the greater between the
maximum operational line load (MOLL) and maximum exceptional line load (MELL), see Table 1-5, as
applicable.
For the equipment relying on squeezing force for the generation of gripping force, see Table 1-5, the
squeezing arrangements shall be designed for the maximum squeezing force, corresponding to Case I
loading, see [4.3].
5.2.4 A&R winches
Guidance note:
The A&R winches may have different maximum line pull than the MOLL of the active risk equipment, due to the addition of the
PLET. This should be considered during design.
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5.2.4.1 Brake capacity
Unless otherwise specified by the manufacture, considering the safety operation philosophy, the minimum
values listed in Table 5-1 apply.
5.2.4.2 Wire rope safety factor
Generally the requirements listed in DNVGL-ST-0378 [5.2.5] apply.
Deviation from the safety factor for the wire could be granted on case by case assessment. A noncomprehensive list of conditions to be considered are:
—
—
—
—
used infrequently
surveyed and maintained closely
replaced more frequently than those used in normal lifting appliances
integrity or inspection programme.
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SECTION 6 SAFETY AND SAFETY EQUIPMENT
6.1 General
All pipeline and cable laying equipment shall be provided with safety functions, reducing the risk connected
to their operation. The safety function requirements are to be founded on a risk based approach, carried out
by the manufacturer and reviewed by DNV GL. This section scope is to introduce the philosophy and indicate
possible methods for defining the requirements.
It is up to the customer to select the technological platform for the safety functions. In principle, all
alternatives documenting an equivalent level of safety will be accepted.
6.2 Safety philosophy
The safety philosophy report shall identify, define and describe the following:
— overall principles and functionality for the safety systems handling accidental events
— description of the functions that shall be implemented as automatic actions, manual action, remote
control, local control, emergency control, back-up control/operation
— specification of failure handling and safe state(s)/condition(s) for the equipment.
The above shall be proposed by the designer. A systematic review or analysis shall be carried out at all
phases in order to identify and evaluate the consequences of single failures in the pipeline and cable laying
systems, such that necessary remedial measures can be taken. The extent of the review or analysis shall
reflect the criticality of the pipeline and cable laying operations, and previous experience with similar systems
or operations.
6.3 Methods
A methodology for such a systematic review is quantitative risk analysis (QRA). This may provide an
estimation of the overall risk to human health and safety, environment and assets and comprises:
—
—
—
—
hazard identification
assessment of probabilities of failure events
accident developments
consequence and risk assessment.
Other methodologies for identification of potential hazards are failure modes and effects analysis (FMEA) and
hazard and operability studies (HAZOP).
As a minimum the following hazards are identified as generic risk contributors for pipeline and cable
Lay systems and shall be addressed in the risk assessment. The following are identified as generic risk
contributors for pipeline and cable laying equipment:
— over-loading may lead falling product and/or to structural collapse
— emergency stop may lead to over-loading the product or equipment due to activation of the emergency
stop
— inadequate product back tension may lead to stress beyond the system's structural strength and to
operational hazards
— lack of visibility due to poor sight or due to laying operations in the driver's blind zone may lead to
operational hazards
— lack of communication between the operators of various equipment part of the laying operation may lead
to operational hazards
— failure in control systems may result in unintentional system response and movements
— failure in safety components/systems may result in hazardous situations due to override of safety limits
— lack of braking capacity may lead to falling product and uncontrolled system movements
— lack of load holding capacity may lead to falling product and uncontrolled system movements
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— blackout/shutdown of power may lead to laying normal operation stop with the system and the load in
unfavourable and unsafe position
— unintended activation of safety functions may lead to system response giving unintentional hazards/risks
— spurious trip of safety functions. Initiation of a safety functions in no-hazardous situations and where
there is no true demand for safety activation due to safety- or control system failure, may cause other
types of hazards/risks
— hazards due to activation of safety functions which may lead to secondary effects that may be harmful to
the system and/or the product
— fire/fire ignition may arise from the system itself or from the ship/installation, and thereby lead to
disaster.
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SECTION 7 TESTING
7.1 General
The testing requirements listed in DNVGL-ST-0378 Sec.14 are considered valid for the pipeline and cable lay
systems with the following consideration.
Safety and functional tests shall be performed as applicable, based on the functionality and operation of the
specific equipment. The testing procedure shall be harmonized with the conclusions from the risk analysis,
see [6].
The design of equipment shall incorporate suitable arrangements to facilitate initial load testing and any
periodic testing.
The test setup shall be suitable in making the system properties described in the test objective observable to
the surveyor.
Test setup documentation shall describe properties of the test setup needed to execute the test cases as
intended. It shall consist of description and argumentation showing that the test setup is adequate in making
system properties observable to the surveyor.
Guidance note:
The description should include what parts of the equipment or installation spread are included or excluded from the test setup,
together with the rationale for doing so.
All inputs and outputs to/from the target system, and why they are included or excluded from the test setup, should also be
described.
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The functional and failure testing shall be carried out in accordance with the approved testing procedure.
The order and objective of the individual test cases to be part of the test scope shall be included in the test
procedure. For each test case the following shall be provided:
—
—
—
—
—
—
—
unique identifier
objective
initial condition
how to perform the test case, including the inputs (signals, button-push, etc.)
what to observe during the test
acceptance criteria for each test (expected result)
actual test result.
All test activities shall be documented into a document providing a description of:
—
—
—
—
—
what has been tested
where and when the testing has been performed
who has attended the testing
all results from the testing, together with any limitation to the testing
list of non-conformities, tagged with a responsible party for follow up within a set due date.
The findings shall, as a minimum, be categorised into safety critical and non-safety critical. This
categorization shall be agreed with the DNV GL.
7.2 System testing
7.2.1 General
7.2.1.1 Equipment in class scope
The equipment or installation spread shall be subject to on-board tests prior to be taken into use.
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If the equipment shall be installed on vessel assigned DNV GL class notation Pipe Layer Vessel or Cable
Layer Vessel, DNV GL shall approve on-board test procedures, conduct on-board installation survey as well
as witness final on-board testing of the equipment or installation spread.
If complete functional and failure testing are documented to have been carried out at manufacturers'
location, limited functional and failure testing may be carried out after final installation. In such case, the
proposed test plan shall specify the extent of the limited test scope to be done after final installation.
Systems/equipment shall be tested under working conditions (or equivalent), according to a written test
program.
7.2.1.2 Equipment not in class scope
If the certification of the equipment has been concluded at the manufacturer, on-board test procedures as
well as witness/acceptance may be endorsed by a competent person accepted by flag/state authorities.
7.2.2 Functional and failure testing
System testing is function and failure testing which shall be performed to demonstrate that systems and
equipment fulfil the requirements of this recommended practice.
Failure testing shall be performed to demonstrate that the systems and equipment reacts to failures as
described by manufacturer, and in accordance with applicable requirements concluded from QRA, see Sec.6.
Scope shall as a minimum include the following:
— Function testing according to requirements defined from Sec.6 (based on FMEA).
— Failure testing according to requirements defined from Sec.6 (based on FMEA).
— Verification of system settings, such as adjustment of controllers and system calibration of sensors and
alarms.
It shall be verified that control systems function satisfactorily during normal, abnormal and degraded
operational procedures. The failure modes associated with the above functions identified and addressed in
the failure mode description document and/or FMEA shall also be included in the testing program. Normally,
the test scope shall be focusing on single and common failure modes and common components.
7.2.3 Simulator-based testing
For software dependent systems/equipment, providing safety functions or essential functions, the system
testing shall be performed as simulator-based testing in accordance with [7.2.3.1] to [7.2.3.4], unless the
required system acceptance testing can be performed on the complete system, as built.
Simulator-based testing shall, when applied, provide objective evidence of required functionality (during
normal, abnormal and degraded condition) of the specified target control system (operative essential /
safety).
7.2.3.1 Test set-up requirements
Simulator based testing shall be executed on the actual control system hardware to be installed on the vessel
or on a replica control system, subject to DNV GL approval.
Guidance note:
Replica setup may be used subject to approval. Cloud-based testing by use of soft-PLC may also be accepted.
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The simulator shall run on a unit separate from the control system.
Testing shall be performed on released software revisions for both simulator and control system(s) such that
the software is uniquely identified.
Testing shall be executed on the same test setup and software as validated through the test setup validation
activity, see [7.2.3.3], and according to DNV GL approved test scope/program.
Testing shall be performed and test results shall be documented in the presence of the DNV GL surveyor.
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7.2.3.2 Simulator framework
All (relevant) I/O shall be interfaced between control system and simulator. If any signals are ignored/not
interfaced, this shall be documented and agreed upon in writing before test is executed.
It shall be possible to monitor and/or trend all I/O-signals between simulator and control system.
It shall be possible to introduce/simulate typical control system failures to the system, such as broken wire,
value out of range, noise on signals, command errors (functions being executed without being commanded),
execution errors (functions not being executed when commanded etc.
The simulator shall be adequate for the type of failures intended to be tested.
Guidance note:
Failures may either be introduced by manipulating the command or sensor signal, while others may have dynamic and/or spread
effects, requiring to be generated from the simulator to propagate correctly to all affected signals.
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7.2.3.3 Simulator accuracy and test setup validation
The simulator and control system shall run in closed-loop and the simulator outputs shall render a real-life
behavior of the system.
It shall be possible to run all the functions in the control system (target system) without the need of manual
manipulation of simulator signals.
A simulator based test setup shall be validated with validation tests demonstrating adequacy/suitability for
the purpose (test objective) and that it does not mask errors in the target system.
Before the validation testing is performed, it shall be verified that there are no active nor ignored/suppressed
alarms in the system that may have impact on the testing.
Test setup validation shall be performed and validation test results shall be documented in the presence of
the DNV GL surveyor.
Guidance note:
1)
The key element for planning the validation activities is to analyse the test objective, and identify possible critical factors/
elements in the test setup which may invalidate the test results. A set of relevant validation activities for the test setup should
be identified, and measures for limiting possible inaccuracies and uncertainties should be described.
2)
One possible cause of masking errors in the target system, is that a parameter in the target system is just copied into the
simulator configuration. If this parameter is wrong, it will be wrong in the simulator as well, making it difficult to identify the
error when both the target system, and the simulator is using the same (wrong) parameter value.
3)
The validation tests may be performed before the surveyor arrive at test site. Results from the validation tests should be made
available for the surveyor for review, and the surveyor may request some of the validation tests to be repeated before testing
starts.
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7.2.3.4 Redundancy and failure response tests
For redundant systems, a selection of tests within each system analysed in the FMEA shall be carried out.
Specific conclusions of the FMEA for the different systems shall be verified by tests when redundancy, fail
safe response, or independency is required. The test selection shall cover all specified technical system
configurations.
The test procedure for redundancy shall be based on the simulation of failures and shall be performed under
as realistic conditions as practicable, e.g. by use of simulators.
Guidance note:
It is understood that not all failure modes in all systems are possible to simulate. For such failure modes the acceptance of the
system will be based on the theoretical FMEA, and hence the documentation analysis of these failure modes should be emphasized
in the FMEA.
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7.3 Prime movers and fluid power systems
Relevant parameters such as power, ambient temperature and pressure, exhaust gas temperature etc. shall
be measured and recorded.
Pressure testing of hydraulic components may be witnessed by the surveyor. The tightness of the systems
shall be checked after the installation of the components and during functional testing.
Automatic control, remote control and alarm systems connected with power systems shall be tested.
After the test, the lubricating and/or hydraulic oil filters shall be checked for solid particles. Other
components of machinery may be required opened up by the surveyor.
7.4 Electrical installations
Insulation-resistance test shall be carried out for all outgoing circuits between all insulated poles and earth
and, where practicable, between poles. Under normal conditions a minimum value of 1 mega ohm shall be
obtained. This also applies to instrumentation and communication circuits with voltages above 30V A.C. or
D.C.
The insulation resistance of a motor shall not be less than:
tested on a clean and dry motor when hot.
When found necessary by the surveyor, switchgear shall be tested on load to verify its suitability and that
operating of over-current release and other protective measures are satisfactory. Short circuit tests in order
to verify the selectivity may also be required.
7.5 Load test
7.5.1 Pipeline and cable laying equipment (active and passive)
The test load applied to a pipe and cable laying equipment shall be agreed with DNV GL, keeping compliance
with ILO 152 requirements. It is recommended that testing is carried out with corresponding MOLL or
equivalent maximum operating load.
In addition the testing of equipment will consider also the harmonization of equipment with the product
handled and the calibration of load cells.
7.5.2 Pipeline and cable laying equipment (storage)
With respect to the heavy storage equipment, functional testing at lower load than maximum storage load
(MSL), see Table 1-5, may be permitted and shall be confirmed with DNV GL on a case by case.
7.6 Periodical surveys
7.6.1 General
For vessels with class notation Pipe laying vessel or Cable laying vessel, it is the owners responsibility
to arrange for periodical surveys, to record substantial repairs, modifications, etc., and to maintain adequate
records to ensure traceability in accordance with class/statutory/flag requirements.
In the remaining of this subsection recommendation for surveys, tests and follow up are described ensuring
this traceability.
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For pipeline and cable laying equipment included in the class scope, the surveys and approvals are carried
out as part of classification's periodical survey scheme (see DNVGL-RU-SHIP Pt.7 Ch.1) including:
— annual survey
— a survey every five years (renewal survey).
Before carrying out a periodic examination or test, the surveyor shall refer to the initial certificate and to the
periodical inspection report.
7.6.2 Survey, tests, repairs
7.6.2.1 General
The surveyor may require other or additional tests and examinations, and dismantling if considered
necessary.
7.6.2.2 Procedure
It shall be verified that initial certification, or thorough examination every five years for installations older
than five years, has been carried out and is valid up-to-date.
Parts which are found to be worn or corroded to a significant degree shall be required to be replaced or
repaired as found appropriate. For alterations typically involving structural modifications and/or modifications
to systems and safety functions/ equipment see [7.6.5].
7.6.3 Annual survey
To be conducted at least once every 12 months (surveys accepted to take place within a time-period ±3
months from the anniversary date of the initial certification/re-certification of the pipeline and cable laying
equipment.
Items to be considered for annual survey:
— Structural condition (damage (cracks, deformations), wear-and-tear, corrosion). NDT shall be applied
when deemed necessary. Damages affecting the primary structure shall be reported. For repairs see
[7.6.5].
— It is expected that a list of consumables is included in the operational/maintenance manual of the pipeline
and cable laying equipment. Consequently, it shall be checked that regular maintenance has been
performed as per manufacturer’s specification and that worn-out components have been/shall be replaced
with equivalent parts.
— Thorough visual inspection of bolted connections (no dismantling is required, unless deemed necessary by
the surveyor).
— Support structure (foundation and connections to the deck).
— Excessive clearance and proper lubrication in hinged connections.
— Wire-rope, including end attachments, with respect to wear, broken wires and corrosion.
— Visual inspection of the pipeline and cable laying equipment’s general operational condition, with particular
focus on:
— the slewing system (slewing bearing condition, proper lubrication, bolt condition and pretension, etc.)
— the telescoping system (including sliding surfaces)
— the luffing system.
— Functional test, including assessment of the control, safety and emergency systems (including power
supply) and alarms.
— Visual inspection of the hydraulic system (e.g. leakages, corrosion, etc.) and correct safety valve
adjustments.
— Examination of electrical installation with respect to general condition, support, physical protection, fire
hazard and personal safety.
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— It is expected that software and hardware change/update procedures are included in the operational/
maintenance manual of the pipeline and cable laying equipment. Consequently, it shall be checked
that the changes/updates have been handled according to the pipeline and cable laying equipment
manufacturer’s specifications by the manufacturer’s appointed representative. It shall be documented
that these changes do not affect the safety of the pipeline and cable laying equipment. In case major
alterations are identified, the follow up shall be as per [7.6.5].
— Marking (as per test certificates).
— Provisions for securing of the pipeline and cable laying equipment during open sea conditions.
— Fire extinguishing system (sprinkler), if relevant.
7.6.4 Renewal (5-yearly) survey
To be conducted at least once every five years (surveys accepted to take place within a time-period of ±three
months from the anniversary date of the initial certification/re-certification of the pipeline and cable laying
equipment and systems).
In addition to the examinations listed in [7.6.3], the following additional inspections and load test shall be
carried out:
— Load testing and examination after testing as required for initial certification.
— Hinge pins for the luffing and telescoping systems (i.e. connecting pins for the hydraulic cylinders,
sheaves, equipment hinges, etc.) to be confirmed documented as dismantled (opened-up), examined and
found in order once during the last five years, or to be opened now.
— Visual examination of all bolted connections, including checking of correct torque setting for 20% of the
bolts in each connection. If any significant torque variation is found during this examination another 20%
of the bolts shall be checked. If any significant torque variation is found during the second examination,
then all bolts in the connection shall be re-tightened as per manufacturer’s specification.
— Slewing bearings to be opened up and internal fillets, raceway and bolts to be subjected to MPI.
Exemption to opening-up of a bearing will be granted provided:
i)
ii)
The equipment has an approved securing device (retainer) fitted.
The slewing bearing has been specially adapted and approved by DNV GL for non-destructive crack
detection.
iii) A company is available, possessing method, skill and specially trained operators within nondestructive crack detection of bearings in question. The company, operators and qualification tests to
be approved by DNV GL in each case.
iv) A procedure including regular clearance measurements established when the equipment was new,
grease sampling and fatigue evaluations are adopted in agreement with the equipment and slewing
bearing manufacturer.
For single ball slewing bearings, opening up may be waived unless required upon detection of
unacceptable clearances, excessive noise, etc. holding-down bolts:
— 20% of bolts shall be removed and examined. The initial 20% shall be taken in the most loaded sector
of the equipment. If any significant defects are found during this examination another 20% are drawn.
If any of this second set is found to be defective then all bolts shall be drawn.
— If the first 20% are found to be acceptable and the examination is stopped, a maintenance schedule
shall be established for examining the remaining 80% during the 5 years period.
— When refitting, all bolts shall be pre-stressed as stated in the equipment manual or as found on
approved drawings.
— Functional testing of manual protection system and automatic protection system.
— In case the equipment control system has been tested by means of simulator based testing, the follow-up
shall include retesting of the control system as per previously approved test procedure updated to reflect:
— changes in the target system
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— changes in the simulator test tool
— to vary and increase the total test scope during the system lifetime.
7.6.5 Alternative Survey
The traditional time based survey may be replaced by a lifetime assessment program and corresponding
overhaul plan based on continuous monitoring of design work periods for all main pipe or cable laying
system's components. A data recorder system accepted (approval may be required) by DNV GL and covering
all movements of main components shall be used. The lifetime assessment program and corresponding
overhaul plan shall be approved by during the design phase of the pipe or cable laying system, and be
according to ISO 12482.
7.6.6 Repairs and modifications
After renewal or substantial repair of damaged parts of the primary structure of a pipeline and cable laying
equipment, it shall be surveyed. This may include strength testing. Renewal or repair of damaged parts shall
be carried out using DNV GL approved manufacturing procedures and materials which are at least equivalent
to the original.
Modifications affecting the primary load bearing structure shall be submitted for approval.
The repair shall be noted on the certificate and the repair report shall be attached to the certificate as an
appendix.
If a pipeline and cable laying equipment is rebuilt, repaired with different materials or profiles with different
cross-sections or otherwise significantly modified (e.g. increased length, etc.), it shall be re-approved. The
old certificate shall be marked deleted and attached to the new certificate.
For software modifications, it will be required to assess the impact that the changes might have on the
originally approved system and advise regarding any testing to be performed in order to maintain the validity
of the DNV GL product certificate.
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Changes – historic
CHANGES – HISTORIC
There are currently no historical changes for this document.
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About DNV GL
DNV GL is a global quality assurance and risk management company. Driven by our purpose of
safeguarding life, property and the environment, we enable our customers to advance the safety
and sustainability of their business. We provide classification, technical assurance, software and
independent expert advisory services to the maritime, oil & gas, power and renewables industries.
We also provide certification, supply chain and data management services to customers across a
wide range of industries. Operating in more than 100 countries, our experts are dedicated to helping
customers make the world safer, smarter and greener.
SAFER, SMARTER, GREENER