optimises your technology PIPE VIBRATIONS - Windows · PDF file•Calculation methods ......
Transcript of optimises your technology PIPE VIBRATIONS - Windows · PDF file•Calculation methods ......
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optimises your technology
www.fsdynamics.fi
PIPE VIBRATIONSVIBRATIONS IN NUCLEAR APPLICATIONS, OCTOBER 4 2016
ANTTI LEHTINEN
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 2/40
• Introduction, FS Dynamics
• Introduction, ”Pipe vibration – analysis and mitigation” project
• Workflow for the analysis and mitigation of pipe vibrations
• Pipe vibration analysis methods
• Classification of pipe vibration problems occurred
• Pipe vibration mitigation
• Evaluation of the mitigation methods
• Conclusions
• Future work
Contents
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 3/40
Introduction
FS Dynamics
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 4/40
FS Dynamics
Fluid Dynamics
Structural Dynamics
Nuclear Engineering
FS Dynamics’ Organisation
• Founded in January 2004 in Sweden
• Head Office in Gothenburg
• 8 Local offices, 6 countries
• Corporation + 6 daughter companies• FS Dynamics Denmark founded in 2009
• FS Dynamics Finland founded in 2010
• FS Dynamics Norway founded in 2013
• FS Dynamics Portugal founded in 2016
• FS Dynamics UK founded in 2016
• 3 competence based departments
• 170 co-workers, 33 in Finland
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 5/40
The FS Dynamics Concept
• Focus on CAE only
• FEM, CFD, MBS
• Multiple Industries
• In-house & On-site services
• Collaboration & Learning
• Excellent engineers
• Long-term relations
Business infrastructure
• Full In-house CAE – environment
• ISO 9001:2000 Certified
• Partnerships with major clients & Satellite setups available
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 6/40
Introduction
”Pipe vibration – analysis and mitigation” project
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 7/40
• Elforsk/Energiforsk project in 2014 – 2015:
• “Pipe vibrations – Analysis and Mitigation”
• The objective was to:
• Assemble knowledge and experience in the area of pipe vibrations problems
• Obtain information of how they were examined and mitigated.
• The nuclear power plants participating in the project were:
• Oskarshamn
• Ringhals
• Forsmark
• Olkiluoto
Background
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 8/40
Motivation: Example of losses due to unplanned unavailability
Forsmark 2: Energy availability 1996-2015
Source: IAEA Operating Experience with Nuclear Power Stations in Member States 2016 edition
Pipe and valve
vibrations
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 9/40
• Obtaining and investigating reports from the participating nuclear power plants
• Visiting the sites and interviewing the staff.
• Obtaining and investigating additional documentation as agreed in the interview meetings.
• Analyzing and grouping the pipe vibration problems and mitigation methods.
Conducting the work
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 10/40
Workflow for the analysis and mitigation of pipe vibrations
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 11/40
• Existing vibrations
• Vibrations that have already been observed or are suspected to exist at the plant
• The emphasis in the analysis is often in measurements of the existing system
• Potential future vibrations
• Vibrations which do not exist or are at low levels
• There is a suspicion that vibrations might arise, e.g. due to:
• Power uprate
• Component replacement
• Typical analysis methods are simulations or physical model tests.
Different workflows
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 12/40
Typical workflow, existing vibrations
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 13/40
Typical workflow, uprate or replacement
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 14/40
Pipe vibration analysis methods
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 15/40
• Can be divided into two main categories:
• Measurements
• Calculation methods
• Often measurements and calculation methods complement each other
Analysis methods
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 16/40
• Different process conditions and mitigation solutions can be tested without restrictions
• Relevant variables can be investigated at any location
• Different calculation methods include:
• Spreadsheet calculations
• Structural simulations (FEM)
• Fluid dynamics simulations (CFD)
• Thermohydraulic simulations
• Acoustic simulations
Calculation methods
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• Will be covered in the next presentation in the agenda
Measurement methods
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 18/40
Classification of pipe vibration problems occurred
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 19/40
• Two different kinds of classification are used for the problems based on
• Location
• Physics
• Different classes of these two categories were created
• The mapping between problems and classes is not one-to-one
• Many of the problems belong to several classes
Classification
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 20/40
• Pipe vibrations related to valves
• Main steam line vibrations (not valve related)
• Pump induced vibrations
• Other vibrations
Classification based on location
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 21/40
• Flow induced vibrations
• Acoustic resonances
• Water hammer
• Structural resonance
• Flexible piping
• Multiphase mixture
• Other vibrations
Classification based on physics
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 22/40
Classification of occurred problems
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 23/40
Pipe vibration mitigation
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 24/40
• The mitigation methods were divided into two main categories:
• Methods that aim to reduce excitation for vibrations
• Methods that aim to reduce vibration response
Classification of mitigation methods
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• Improved fluid dynamic design
• Reduced gas/liquid interaction
• Dissolved air
• Condensation/vaporization cycles
• Expansion chamber
• Replacing a component
• Avoiding certain operating conditions
• Other possible mitigation methods (not used in the studied cases):
• Reducing excitation from a pump
• Modified system to reduce acoustic resonances
• Frequency converters
Mitigation reducing excitations
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 26/40
• Vibration dampers
• Added weight
• Added supporting
• Building valves together
• Hydraulic hoses
• Other mitigations:
• Changing pump rubber feet and foundation
• Steel wool dampers
• Welding stiffener in the foundation
• Stiffening pipes to the wall
• Wood bars to support the piping
• Motion limiters
Mitigation reducing response
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Applied and considered mitigations (excitation)
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Added weight
Replacing a component
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Avoid certain operationg conditions
Vibration dampers
Improved fluid dynamic design
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 28/40
Applied and considered mitigations (response)
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A.3. A.3.
A.21.
A.7.
A.16. A.16.
(A.4.) (A.4.)
(A.19.) (A.19.)
A.15.
A.17. A.17.
Expansion chamber A.11.
Reducing excitation from pump (A.17.) (A.17.)
Modified system to reduce acoustic resonances (A.19.) (A.19.)
A.11.
A.15.
A.4. A.4.
A.1.
A.13.
A.9
A.10.
A.12.
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A.5.
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(A.17.) (A.17.)
A.4. A.4.
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Building valves together A.6.
Hydraulic hoses A.7.
Added support
Mit
iga
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or
resp
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seM
itig
ati
on
fo
r e
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tati
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Added weight
Replacing a component
Reduced gas/liquid interaction
Avoid certain operationg conditions
Vibration dampers
Improved fluid dynamic design
Mitigation Flo
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du
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vib
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s
Aco
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A.16. A.16.
(A.4.) (A.4.)
(A.19.) (A.19.)
A.15.
A.17. A.17.
Expansion chamber A.11.
Reducing excitation from pump (A.17.) (A.17.)
Modified system to reduce acoustic resonances (A.19.) (A.19.)
A.11.
A.15.
A.4. A.4.
A.1.
A.13.
A.9
A.10.
A.12.
A.12.
A.5.
A.18. A.18. A.18.
(A.17.) (A.17.)
A.4. A.4.
A.17. A.17.
A.19 A.19
A.21. A.21.
A.6.
Building valves together A.6.
Hydraulic hoses A.7.
Added support
Mit
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fo
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Mit
igat
ion
fo
r e
xcit
atio
ns
Added weight
Replacing a component
Reduced gas/liquid interaction
Avoid certain operationg conditions
Vibration dampers
Improved fluid dynamic design
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Evaluation of the mitigation methods
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 30/40
• Evaluation of a mitigation project consists of:
• How much pipe vibrations have been reduced
• What kind of problems have there been during the mitigation project
• What kind of adverse effects has the mitigation caused
Evaluating mitigation
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• Effect on RPV level measurement
• Increased valve opening times
• Accessibility and maintenance issues
• Increased pressure drop
• Attachment of the added weights
Problems and adverse effects
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Success of reducing vibrations
Reducing
excitations
Reducing
response
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Conclusions
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• Knowledge of pipe vibration analysis and mitigation methods is very valuable for ensuring the continuous and safe production at the nuclear power plants
• Pipe vibration problems occurred at the sites over the years cover a wide range
• Several small problems that can be easily mitigated
• But also larger problems which have required years of work
• Severe problems are not frequent
• But when they occur, the effect on unit operation is large
Conclusions
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 35/40
• Many similarities between the problems at different sites
• Problems were grouped according to location and physics
• Problems belonging to the same groups typically had many similarities with each other
• The investigation showed that there have already been very large benefits from cooperation between the sites
• Information from other sites has been used to avoid problems
• Used components have been exchanged between sites
• Many of the problems are still rather unique
• It is not always possible to reuse a previously successful mitigation method
Conclusions
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• It is always preferable to take into account possibility of pipe vibrations before:
• Power uprates
• Major modifications
• Handling the vibrations before they exist is often easier than when they already have occurred
• The workflows for analysing and mitigating vibrations are different for existing and potential future vibrations
• It is preferable to analyse vibrations both with measurements and simulations
• Measurements give more accurate information of the current status
• Simulations provide more predictive information
Conclusions
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• Mitigation methods were divided into two main categories, based on whether they target:
• The excitation for the vibrations
or
• The vibration response
• The mitigation targeting the excitation was found to be on average more successful
• Often mitigation targeting on response is implemented first
• These kind of mitigations are usually simpler to implement
• They give time for planning and implementing final mitigation
Conclusions
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 38/40
Future work
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 39/40
• M.Sc. thesis work ongoing
• B.Sc. Mikko Merikoski: ”Pipe vibrations and mitigation in power plants”
• The previous work will be extended with:
• Literature survey of pipe vibrations at other nuclear power plants
worldwide
• More quantitative information e.g. of the vibration levels in the problems
studied in the previous work
Ongoing work
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Antti Lehtinen: ”Pipe vibrations”. Vibrations in nuclear applications, Oct 4, 2016 Page No: 40/40
Thank you!