6 - dnv - composites repair jip - new approach to repair of fpso's without hot work using...
Post on 18-Jan-2016
15 Views
Preview:
DESCRIPTION
TRANSCRIPT
Slide 1
Slide 2
JOINT INDUSTRY PROJECT UPDATE
“A New Approach to Repair of FPSO’s Without Hot Work”
A. T. Echtermeyer, M. J. Larsen & K. P. FischerDNV, Høvik, Norway
presented by
Johan GärdinMobile Offshore Units / FPSO, DNV SEA & ANZ, Singapore
Telephone +65 67791266johan.gardin@dnv.com
www.dnv.com
Slide 3
Typical FPSO In-Service experience:
Structural and materials protection issues:
• Integrity of Hull (3 of 4 suffer cracking in tank boundaries)
• Integrity of Ballast and cargo piping (construction standards for cargo and ballast piping appear inadequate. Weld failures, corrosion & subsequent leaks)
• General corrosion and coating issues (need for good inspection programme)
(Source OLF, Norway: data for 4 FPSO)
Slide 4
FPSO In-Service Inspection:
Ballast tank surface area 100,000 – 200,000 m2
The inspectability of most FPSO’s and tankers is a nightmare. Design for inspectability rarely enters the design engineer’s mind
until he has to participate in the inspection himself. ” (R. G. Bea)
Slide 5
FPSO In-Service Failures:
INADEQUATE PROTECTION INADEQUATE DESIGN or OVERLOAD
Local or General Corrosion Fracture
Slide 6
Ideal Repair:ADHESIVE PATCH:
•IN-SITU ON LOCATION
•ONLY REPAIR AREA
•NO CUTTING/WELDING
•MOST GEOMETRIES
•VERY!
•VERY!
•EQUIV. TO WELDING
•20 YEARS EXPERIENCE
NO PRODUCTION STOPNO HOT WORK
NO GOING OFF LOCATION
ADAPTABLE TO ANY CASE
COST EFFECTIVE
QUICK
LOW TECHRELIABLE
Slide 7
Repair TimescalesExtensive welded repairs
Minor welded repairs
Patch repairs
Shut down production
Wait for weather-window
Wait for weather-window
Production interruptions avoided – only damaged area is shut down
Transit to yard
Shut down production
Clean damaged area
Docking + repair
Repair Repair & cure
Start production
Transit to field & hook up
No interruption in productionMonths Weeks
What Is Adhesive Patch Repair?
Slide 8
Principle:
• A damage (e.g. hole, crack, corrosion) is discovered and needs repair
• A patch is fabricated from a structural laminate
• The patch is adhesively bonded to the substrate to repair the damage
Slide 9
• MATRIX
What Is an Adhesive Patch?
LAMINATE+• REINFORCEMENT
• ADHESIVE
Slide 10
What Is an Adhesive Patch?
• ALTERNATIVE PRODUCTION METHODS:
• WET LAY-UP (Dry Reinforcement and Resin applied directly to substrate by roller and cured in situ)
• PRE-PREG (Impregnated patch and adhesive applied to substrate and cured together under heating)
• INFUSION (Dry Reinforcement and low viscosity Resin applied directly to substrate and cured in situ under vacuum bag)
Slide 11
What Is an Adhesive Patch?
Typical patch materials depend on application:
• MATRIX POLYMERS:• Epoxy, Polyester, Vinylester, Urethane...• REINFORCEMENT:• Glass fibre, Carbon fibre, other high performance fibre
types.• Multi orientation (csm), Woven roving (0°/90°), Uni-
directional, or Combination mats• ADHESIVES:• Structural adhesive: May be identical to the matrix or a
dedicated structural adhesive
Slide 12
Design, Production, Installation
• Optimum PATCH DESIGN depends on damage type, location, strength requirements, working conditions during application, available time for repair...
• Choice of production and installation METHODmust suit material choice and design of patch repair
• Skilled WORKMANSHIP, good PROCEDURESand QUALITY ASSURANCE during design and production / installation is paramount!
Slide 13
Limitations to Patch Repair
• Some polymers may be SHE HAZARDS• Substrate CLEANLINESS is critical• STIFFNESS may be difficult to achieve• SHEAR AREA between patch and
substrate must be adequate• PEELING STRESS must be avoided
Slide 14
Opportunities with Patch Repair
• ‘Smart materials’ for performance monitoring
• Tailor-made directional properties• Lightweight – easy handling
Slide 15
Current Applications of Patch RepairsCurrently used for rehabilitation within:• Infrastructure / civil engineering• Navy vessels• Process plant piping • Offshore piping and non-structural applications
Extension to FPSOs could be:• Structural applications, such as:
– Reinforcing corroded panels (compensating for loss of thickness)– Bridging of cracks in stiffeners or brackets (relieving hot spot
stress)– Strengthening of decks, frames bulkheads etc. to carry additional
equipment• Non-structural applications, such as:
– Bridging of cracks or holes in platforms etc
Slide 16
Application Examples, DML
Deck repairs on naval shipsRepair carried out during scheduled maintenance docking:
Avoids time-consuming removal / protection of mechanical / electrical outfitting prior to welding
All photos courtesy of DML Composites
Slide 17
Application Examples, DML
Rehabilitation of pipelinesRepair can be permanent or temporary
Repair can often be carried out without shutdown of production:
Avoids expensive down-time
All photos courtesy of DML Composites
Slide 18
Application Examples, DML
Repair of flare tower:Repair carried out offshore
Repair completed without hot work, avoiding fire hazard
All photos courtesy of DML Composites
Slide 19
Qualification of Patch Repairs for FPSO
DNV is currently developing a qualification guideline for adhesive patch repairs of FPSO
Key objectives include:• Provide a LINK between existing DNV documents for
design of offshore ships and design of composite components
• Provide SPECIFIC GUIDANCE on design and qualification requirements for patch repairs on FPSO
• Develop and test demonstration examples to establish QUALIFICATION TEST requirements
Slide 20
Use of DNV’s Reliability ExperienceThe basic functional requirements for a patch are simple:• The required strength and stiffness must be restored
• The repair must resist the local environment
• The growth of the damage must be stopped
• Additional strengthening may be required if the damage is due to a design flaw
Acceptance criteria for patch repairs are developed based on:• DNV experience with FPSO and ships in general
• Recently developed acceptance criteria for composite materials
Safety factors calibrated to
ensure consistent safety level
Loads
Material properties
Structural reliability approach
Qualified repair
Slide 21
Use of existing DNV documents
DNV-OS-C101 Design of offshore steel structures, general
DNV-OS-C102 Structural design of offshore ships
DNV-RP-C203 Fatigue strength of offshore steel structures
DNV Rules for ships provide background
Qualification procedure for
adhesive patch repairs
DNV-OS-C501 Composite ComponentsDNV-RP-A203
Qualification procedures for new technology
Specific information and technical background for patch repair design and qualification
Slide 22
Demonstration Examples
Key objectives:• Demonstrate principles in patch design and
in qualification process • Provide information on failure modes and
general performance of generic patch repair designs
• Establish base cases to be used as reference when designing full scale patch repairs
Slide 23
Demonstration Examples
Two demonstrators are chosen:“The corroded panel” – simulating corrosion damage and
leakage in tank or shell plating“The fractured stiffener” simulating a fatigue crack in a
beam (local or global stiffening member)
Slide 24
Corroded Panel Demonstrator
Slide 25
Panel Repair: Production Sequence
Slide 26
Fractured Stiffener Demonstrator
Artificial crack
Composite repair by ”pre-preg” or prefab plates
Slide 27
Demonstrator Testing
Corroded panel demonstrator Fractured stiffener demonstrator
Detail of notch with strain gauge – ready for testing
Slide 28
Continued Work in a Phase 2
2004-2006:• Extension of test programme
(small scale testing – bond zone properties)• Updating the document with more test
results• Establishing more repair base cases• Performing a full scale field repair on an
FPSO in operation
Slide 29
Conclusions
• Fire Adhesive patch repairs enable field repairs of FPSOs and other offshore structures without hot work.
• Hazards and shut-down requirements are minimised.
• A framework for quality assurance and procedures for qualification of patch repairs will help avoid basic design and production errors, which could potentially lead to repair failures.
• This JIP will result in an official DNV document providing such a framework.
• Successful full scale field demonstrations will pave the way for patch repairs as an accepted technology in the future.
Slide 30
AcknowledgementDNV would like to thank the following companies in Phase 1 of the JIP “Qualification of Adhesive Bonding in Structural Repairs of FPSO’s” for the permission to present this paper:
• ConocoPhillips• Norsk Hydro• Petrobras (CENPES)• Petronas (PRSS)• Shell-Enterprise Oil• Statoil
DNV would also like to thank Devonport Royal Dockyard Ltd (DML) for their cooperation in the JIP and also for their contribution to this paper.
Slide 31
PHASE 3(?):
MEGA-SCALE TESTING
top related