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How To – Fabrication of DNV Certified Skids 2.7­1
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How To – Fabrication of DNV Certiɮed Skids 2.7-1
REPRESENTING
How To – Fabrication
of DNV Certi€ed Skids
2.7-1
 gregbright
 July 14, 2015
Skids
 2 Comments
 DNV Fabrication
Increased demand for fabricated DNV skids is being driven
by quality and safety concerns for equipment being
installed on any DNV classed vessel, including any offshore
platform, marine vessel, FPSO, drill ship, or other marine
installation. These concerns are at an all­time high as a
result of the Macondo blowout in the Gulf of Mexico in
2010.
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Operating these complex systems and facilities requires
complex fabrication. Our principal’s DNV certification
Housto...
procedures assure owners, authorities, and other
stakeholders that the DNV classed facility has certified
equipment aboard and complies with DNV classification
rules and requirements – independent of location.
Classing Societies and the IMO
IMO is the International Maritime Organization and it is the
United Nations agency responsible for the safety and
security of shipping and the prevention of pollution by ships.
The IMO is the standard­setting authority for the safety,
security, and environmental aspects of international
shipping. It creates a regulatory framework for the shipping
industry that is universally adopted.
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The IMO has adopted standards for other “recognized
organizations” like the DNV which are called classification
societies.
RECENT POSTS
At Ocean Fab, safety, quality, the environment, and
compliance with DNV standards are our number one
concern. In order to gain DNV emblems for any skidded
SubSea – Wye Skids
– Controls Mudmat
– Quayside Barge
equipment, a number of approval and certification
procedures must be followed. Our principals have many
Loadout
years’ experience with complex fabrications, including
subsea and offshore / topside fabrication.
DNV has traditionally been more popular in European
waters, but since it has become the number one classing
society in the world, more and more super major oil
companies and operators are requiring that any equipment
going on a DNV Classed Offshore Installation going
anywhere in the world become certified by DNV. Whether
it’s a temporary or a permanent installation – fixed or
floating offshore installations, ships, drill rigs, production
rigs, or offshore vessels, including floating platforms. This
equipment can include rental equipment, skidded
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equipment, shipping containers, seacans, frames, structural
steel, twistlocks, sea fastening clips, deck fastening, waste
skips, tanks – the list goes on and on.
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*Disclaimer: Ocean Fab nor its principals are in any way
affiliated with DNV GL. DNV regulates all of the processes
Ocean Fab
listed below for DNV certification. These are only historical
examples of the processes that we have gone through with
DNV. DNV will be the final authority for any process,
including new ones that Ocean Fab’s principals have to
certify for our clients. The rules change frequently – Please
consult your local DNV office for more details. Ocean Fab is
not an engineering company – however, our principals can
provide engineering services.
Quality Control – Ocean Fab principal’s Quality
Management System ensures the quality of procedures and
facilities by implementing a QMS in accordance with ISO
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9001. QMS audits and approval by the DNV classification
society verify that our QMS meets the high standards and
are qualified to manufacture skids according to those DNV
standards.
Witnessing
Witnessing is a large part of the certification process for
DNV. A DNV surveyor will need to witness numerous
aspects in the process of certification including the weld
procedure approval, welder qualification, the weld startup of
each specific project, and during various milestones in the
project – according to the Quality Inspection & Test Plan.
DNV Surveyors will come and inspect / witness at defined
inspection points.
1. Coupon witnessing – once our written weld procedure
has been approved, a DNV surveyor must come to our
facility and witness the welding of test coupons.
2. Welder Qualifying
3. Start Up
4. Millstone audits according the Quality Inspection & Test
Plan.
5. Inspection of the prototype and the prototype is also
tested
THREE MOST COMMON DNV STANDARDS
FOR DNV CLASSED OFFSHORE
EQUIPMENT
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The three most common standards relate to a portable
offshore unit, and usually involve some type of “Lifting
Operation” either from the dock to the vessel or lifting on
the open seas. The standards apply to any fabricated
enclosure or skid for offshore vessels and marine
applications. They include:
DNV Standard 2.7­1 *Offshore Containers (applies to
skids, frames, enclosures, etc.) – standard for certifying
offshore container transport units and produced by a
privately­held company. As defined by the International
Maritime Organization, an offshore container is a “portable
unit, specially designed for repeated use in the transport of
goods or equipment to, from or between fixed and/or
floating offshore installations and ships.”
Offshore containers are also commonly called “skids” in the
offshore oil and gas community, as they are often used to
transport large components to drilling and production rigs.
These can be as simple as frames that hold the contents.
The skid, along with its contents, is sometimes referred to
as a “skid package.” The three typical phases of transport
are: shoreside (e.g. by fork lift truck), by supply vessel and
lifting to and from offshore installations. The Standard for
Certification includes design requirements related to all
three phases.The requirements for design, testing and
production of offshore containers in EN 12079 are directly
based on DNV Standard for Certification 2.7­1
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DNV Standard 2.7­2 Offshore Service Modules –
Offshore service modules are often designed to perform
temporary services on installations/vessels and therefore
may be moved among different offshore installations/units
and into different national waters.
DNV Standard 2.7­3 Portable Offshore Units – covers all
other types of portable offshore units, other than offshore
containers. The standard is built on the 2.7­1 DNV
Standard and usually involves lifting operations while on the
open seas – versus simply loading and unloading from the
dock.
Note: It’s important to note, that while DNV 2.7­1 most
commonly refers to the term “shipping container” This
standard also covers Skidded Equipment, DNV Baskets,
Mud Skips, Cutting Boxes, Waste Skips, Enclosures, and
Tanks. These can be as simple as frames that hold the
contents. The skid, along with its contents, is sometimes
referred to as a “skid package.”
DNV PROJECT TIMELINE AND
SCHEDULING
Because of the large amount of paperwork, scheduling, and
witnessing involved for final DNV certification, it is
paramount that we work within our client’s expectations for
scheduling. Ocean Fab’s principals have years of
experience with this process and have developed
relationships with local DNV surveyors and other DNV
administration to facilitate this process and keep everything
on schedule.
For DNV approval and certification, there are five basic
steps:
1. Certification of our (or our client specified) written Weld
Procedure, Lab Tests, and Welder Qualification
2. Appraisal and approval of our principals equipment / skid
/ frame design
3. Audit / survey during the initial welding Start Up
4. Production – Audit / survey during the manufacturing of
the equipment
5. Testing of the prototype – For “Type” Approval (Type
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approval means there are a series of the same units being
manufactured over a period of time)
Note: It’s important to note that DNV certification is project
specific. In other words, each new fabrication order we get
from our client has to go through a new DNV approval and
certification process. Even if it is a repeat order for the
same exact product. In some circumstances it is advisable
to get a series of the same manufactured product approved
by DNV – For repeat products which fall under a more
manufacturing mode of construction we can get DNV
surveyors to approve a “Type Approval”.
Step #1 – DNV Weld Procedure Approval
The Survey – Submit Our Written Weld Procedure WPS,
PQR, and lab test specifications / plan for Review &
Compliance – Qualify the welders.
The very first step of the survey process is to submit our
written WPS (Weld Procedure Specification) and PQR
(Procedure Qualification Record) for DNV approval for an in
house welding procedure. This paperwork outlines the
details of what needs to be accomplished, the purpose, the
inspection test program, and what is required from DNV.
We submit WPS, PQR’s, and Lab Testing Specs to a DNV
Welding Engineer for review. Once the Welding Engineer
gives approval, we schedule a DNV Surveyor to be at our
facility to witness the welding of the coupons.
The inspection test program includes: – Verification and
testing of materials – Welder Qualification – Acceptance of
weld procedures – Acceptance of NDE procedures –
Witness and acceptance of prototype testing – Verification
of identification and marking.
Variables / Parameters: Welding Processes, Joint Design,
Positions, Filler Material, Electrical Characteristics, Heat
(Amps x Volts x 60 / Travel Speed), Technique, Pre­heat
interpass and Post weld heat treatment, Shielding, Initial
and Interpass cleaning / grinding
Lab Testing Outline – Coupon Testing Specifications
Visual Testing
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Ultrasonic Testing
Magnetic Particle Testing
Side Bends
Reduced Section Tension Tests
All Weld Metal Tensile
CVN Tests (Charpy V­Notch tests) Specimens with various
notches
Hardness Test – Vickers Hv10
Macros (photographs included)
We then weld the coupons and record the information. All
test welds are witnessed, prepared, welded, and tested in
conformance with the requirements of the specified
Structural Welding Code.
Upon completion of the weld coupons we ship the coupons
to the testing lab to be tested. Lab Testing must be
witnessed by DNV.
After the lab tests have been witnessed and approved, we
the write the lab results/parameters in to the WPS/PQR’s,
then submit those documents back to DNV for the final
approval stamping. The updated PQR’s and WPS will be
based on the supporting data and lab results. DNV will then
do a final review and either provide DNV approval or any
suggested changes.
Once lab testing results are received back at our facility, we
finish filling out the WPS paperwork with the information
provided by the PQR’s. Finally, we submit the completed
WPS, PQR’s and lab testing results to DNV Welding
Engineer for weld procedure approval.
When finally approved, we give a DNV Surveyor the
opportunity to come out to witness the qualification of our
welders to the new weld procedure.
This approval is specific to our company and witnessed by
DNV. Ocean Fab’s principals have been approved for
numerous welding procedure by many of the classing
societies, including ABS and DNV. Often times we can
submit one of our existing welding procedures which has
already been approved by another classing society and
DNV will allow us to use it. However, any existing welding
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procedure still has to go through the proper certification
with DNV for approval and certification.
Step #2 Engineering and Design – of the DNV
Equipment / Structure
Our principals submit the structural design of the offshore
skidded equipment which must be reviewed and approved

by DNV. The design approval process assures that the
design of the equipment which is to be installed on a DNV
classed vessel complies with the DNV rules. This is the
beginning of the process to assure that the fabricated
equipment satisfies DNV’s requirements.
The Design approval includes an initial review, the issue of
comments, and a review of next document revisions to
confirm incorporation of DNV comments. During the design
approval process, our principals can provide approved
engineered drawings. This process can take 6 to 8 weeks.
Design Review Options:
Case Approval – for one off pieces of equipment or small
production runs.
Case by case approval tends to be job specific for a known
batch (customer purchase order) and only valid for that
batch.
Type Approval
If our client needs to manufacture several units over a
period of time a Type Approval is requested from DNV. This
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is only valid for certain time frames and must be renewed
periodically.
Our principals submit the following documentation for
Design Review:
The container’s structural drawings are reviewed according
to the standards referenced in IMO MSC/Circ. 860. Details
of the materials and strength of the cargo containment
structure, as well as the lifting and securing arrangements
are appraised. Drawings must show: – Dimensions and
load ratings – Material specifications – Details of welding
methods and weld sizes – Details of any other fastening
methods – Details of any special treatment for materials –
Details of sealant materials – Details of corner fittings and
closure mechanisms, together with name(s) of the
manufacturer(s) of these parts – Mandatory marking.

The design must also consider all of the various
components and forces subjected to the equipment skid:
For example, the steel, stability against tipping, Design
Temperature, Allowable Stresses, Lifting with the “lifting
set”, Design of lifting sets, Lifting with forklift truck,
Horizontal Impact, Vertical Impact, Container walls,
Minimum material thickness, Welding (some welds are full
penetration welds and others are fillet welds), Floor
(drainage), Doors and hatches, Intermediate cargo decks,
Internal securing points, Fork lift pockets, Pad eyes,
Prototype Testing, Coating and corrosion protection,
Dimensions and strength of lifting sets, weights, and sling
angle calculations.
Step #3 The Start Up for a Specific Unit of DNV
Certified Equipment
Once DNV approves our Design and WPS, the next step,
before we begin welding, is to schedule DNV to witness a
weld start­up. This needs to be done on each new series
(purchase order), even if it’s the same repeat items that
was made before.
At this time DNV can also qualify additional welders and
begin layout for DNV witness / audit of the start­up. Only
after final approved certification and individual welder
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qualification are we ready to fabricate and schedule a DNV
surveyor for a weld start/audit.
For multiple items where our clients need to manufacture
several units over a period of time a “Type Approval” is
requested from DNV . For “Type Approval” The DNV
surveyor will usually audit more often in the beginning until
they’re comfortable with our QMS for the project, then it will
diminish and become random.
We communicate schedule milestones to all parties as we
go along with the project.
During fabrication, welder ID stamps are stamped on each
weld. We provide a Weld Map or written record of which
welder welded what part of the assembly.
Step #4 Production of the DNV Equipment

During the production phase, DNV will periodically visit our
facility and audit the process during manufacture. The
frequency of the audits depends on how comfortable they
are with our quality processes, procedures and adherence
to the design and the Quality Inspection & Test Plan.
Production Inspection – The DNV surveyor typically uses
the following criteria when inspecting during the production
phase.
— Dimensional control
— Visual inspection of weld preparation, welding,
alignment, material marking etc.
— Review of material certificates
— Review of WPS/WPQ, Welders Qualification Tests,
welding consumables
— Review of equipment documentation as necessary
— Review of NDE documentation and report
— Review of the marking
Production Documentation – General Production is
performed according to approved drawings, specifications
and procedures. We must submit our quality plan for
acceptance before production starts. The certification of
each container is based on the following documentation,
which we retain for the time period specified by DNV.
— Approved drawings, including a general arrangement
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drawing
— Structural calculations
— Type approval certificate (where relevant – only for
multiple repeat units)
— Material documentation
— Welding procedure qualifications (WPQ)
— Welding procedure specifications (WPS)
— Welder’s qualification certificates
— Weld Map – (written record of which welder welded what
part of the assembly)
— Report on traceability of materials in the primary
structure
— Report from manufacturing inspection
— Report from dimensional control
— Report from non­destructive examination (NDE).
— Report from prototype testing
— Report from production testing
— Report from final inspection.

Markings – During production, and on the finished product,
we identify the materials used for the primary structure with
the corresponding documentation. When markings are not
visible on the finished product, we provide a log of the
components to identify and ensure traceability of the
materials.
Inspection of Welds – Inspection of Welds Welds are
subject to visual inspection and NDE. All welds are 100%
visually inspected unless otherwise agreed in an MSA.
Step #5 – Testing of the DNV Equipment
“Type” approval of the equipment first involves the
construction and testing of the first article or prototype, built
according to the approved drawings. It must also use the
same materials as proposed for normal production. Tests
include: – Four­point lift using all padeyes – Two­point lift
test using opposed padeyes – A vertical impact test – A tilt
test – Tanks for dangerous cargoes shall in addition be
tested with all the requirements of the IMDG code.
DNV Emblem – Once the DNV surveyor has completed the
manufacturing inspection, witnessed testing and reviewed
the production documentation a “Certificate for Offshore
Container” (Form No. 49.07a) will be issued. The numbered
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DNV emblem for offshore containers (or skid / frame) will
be affixed to the container (or skid / frame). The authorized
DNV surveyor will hard stamp and the certificate number
into the bottom frame below the emblem or in other suitable
location on the primary structure near the emblem.

CERTIFIED WELD PROCEDURES –
QUALIFIED WELDERS – CERTIFIED
DESIGN
Procedure – A procedure is the description of the
technique (method) adopted to preform quality welding as
required by the applicable code. The procedure must be
qualified against the certain standards (Codes)
• AWS D1.1
• DNV, Standard for Certification No.2.22 ‘Lifting
Appliances’ ,
• DNV, Standard for Certification No.2.7­1 ‘Offshore
Containers’,
• DNV, Standard for Certification No.2.7­3 ‘Portable
Offshore Units’,
Welder – The contractor (the fabrication shop) is the entity
qualifying the weld procedure itself, the individual welder is
not certifying the procedure – they are only being qualified
to weld according to the procedure.
We must certify that any of our welders welding to the
previously qualified (in­house) specification have been
tested and are qualified to preform that weld procedure.
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The welder’s Qualification Test Sheets and Welder
Qualification Test Record must be available, attesting to
their ability to weld in accordance to our Welding Procedure
Specification.
Design – The structural design of the offshore skidded
equipment is provided by either our clients or principals.
Whoever is responsible for the design, the design must be
reviewed and approved by DNV. The design approval
process assures that the design of the equipment which is
to be DNV classified complies with the DNV rules. This is
the beginning of the process to assure that the fabricated
equipment satisfies DNV’s requirements.
SPECIAL THANKS TO – T­REX GRAPHICS
AND ANIMATIONS
Graphic image source – T­REX Graphics and animations.
As an added value service, T­REX 3D designs allow clients

the ability to utilize T­REX scale models of a DNV
equipment placement to more easily navigate complex
DNV vessel layouts, effectively allowing operators the
capability to safely place the equipment (virtually) before
actual equipment had been installed.
T­REX work has been featured in E&P Magazine as well as
numerous other industry publications.
T­REX’s render farm facilitates the massive amounts of
parallel processing required to generate 3D animations.
Currently, 150 CPU Cores have been created and are
continuously being added to shorten render times.
Whether we create graphics for the fabricated equipment
we construct for you, or your in­house fabricated equipment
– the animations effectively illustrate to clients how
structures are installed and maintained. We also have a
wide range of structural and piping models, developed into
a fully produced 3D artistic rendition–ready for computer
simulation.
Our clients can also benefit from having their conceptual
ideas illustrated and printed as large­format graphic posters
and interactive PDFs as projects are being developed.
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Our 3D models can provide full functionality of moving parts
and assemblies, exact bill of materials, weights, center of
gravity of components and assemblies, and 2D + 3D cad
drawings.
3D models can also be used in the development of FAT and
SIT layout, procedures, equipment accessibility,
transportation load out, testing and training.Design
packages include: Still Images | Animations | Video
*Disclaimer: Ocean Fab nor its principals are in any way
affiliated with DNV GL. DNV regulates all of the processes
listed above for DNV certification. These are only historical
examples of the processes that we have gone through with
DNV. DNV will be the final authority for any process,
including new ones that Ocean Fab’s principals have to
certify for our clients. The rules change frequently – Please

consult your local DNV office for more details. Ocean Fab is
not an engineering company – however, our principals can
provide engineering services.
About The Author
Gregbright
2 Comments
Choteanan Ch. FEBRUARY 25, 2016
Dear Sirs,
Could you suggest how to become a
fabrication approved and certiɮed by DNV?
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Best regards,
Choteanan Ch.
Reply
gregbright MARCH 2, 2016

Dear Choteanan Ch. Yes, we
can provide DNV certiɮed skid
fabrication services to you. Do
you need DNV certiɮcation in
Thailand, or in Houston, Texas?
Reply
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