Durable offshore wind Corrosion controlseminars.amccentre.nl/Photos/seminar2011/Presentaties/4-B TNO...
Transcript of Durable offshore wind Corrosion controlseminars.amccentre.nl/Photos/seminar2011/Presentaties/4-B TNO...
Durable offshore wind Corrosion control
AMC Seminar, Den Helder, 3 november 2011
Johan van Malsen
Outline of presentation
TNO
Corrosion
Corrosion control
Research and Development within the DOWES project
Get organised - imlementation in an asset management
syestem
3-11-2011
AMC Seminar
Contract research organisation
Since 1932
Independent
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Founded by government
4000 employees
Healthy Living
Industrial
Innovation
Defense, Safety
and Security
Energy
Mobility
Built
Environment
Information
Society
Maritime and Offshore
Structures
• Materials (metals, plastics, composites, thermoplasts, thermosets)
• Bonding (adhesives, welding, mechanical bonding)
Influence maritime environment on structures
Environment • Atmospheric
(sun, rain, wind, temperature) • Tidal zone
(wet/dry cycle, aerobic/anaerobic, radiation, temperature)
• Immersed zone (sea water, temperature, pressure, aerobic/anaerobic)
Protection/Mitigation Solutions
• Protective layers • Durable materials • Lubrication • Monitoring
Degradation
• Wear
(abrasion, friction adhesion and
cohesion, erosion, corrosion)
• Chemical degradation
(corrosion, ageing)
• Biological degradation
4-11-2011
Corrosion
(Electro-)chemical degradation of metals resulting in material
dissolution and loss of mechanical strength
Corrosion damage app. 3-5% of GDP, this amounts to 15-25
billion euro’s per annum!
Important contributors to offshore structures degradation:
- General corrosion in sea water
- Microbiological Influenced Corrosion
- Accelerated low water corrosion
- Localized corrosion (pitting, stress corrosion cracking,
corrosion fatigue and hydrogen embrittlement)
3-11-2011
AMC Seminar
Corrosion Control
Corrosion can be controlled by:
Change the medium and environmental parameters
Materials selection; choose more resistant materials
Protection of the materials by a barrier coating
Protection of the materials by (impressed current) cathodic
protection
Dutch Offshore Wind Energy Services
Structures are required to safely operate for over 25 years
Offshore Wind Parks need online monitoring systems for cost
effective maintenance
Development of sensors for remote monitoring of processes
that cause corrosion to offshore structures
Test and validate available sensors
Reduce maintenance costs by modeling degradation
processes
DOWES – TNO workpackage
Coating degradation
Microbiological Influenced Corrosion
Data transfer to DOWES system
Use data in asset maintenance program
Assessment of coatings: Coating Health Sensor
Protection of steel by coatings is based on barrier principle
Change of barrier function can be monitored by means of
electrochemical measurements
Coatings start to degrade long before visual damage can be
observed
TNO offers technology to measure coating degradation before
it can be visually observed
Principle of coating degradation mesurement
Johan van Malsen
Coating Health Monitor
Test set up
3 coating systems based on coating properties
Conventional Electrochemical Impedance Spectroscopy (EIS)
over whole spectrum from 100000 Hz to 0.1 Hz
Measurements with coating degradation sensor at 0.2, 0.5 and
0.9 Hz
Total exposition period 180 days in artificial sea water
Comparison of the results
Results and evaluation
Johan van Malsen
Coating Health Monitor
Comparisson CHM - EIS
coating 1
1.00E+02
1.00E+04
1.00E+06
1.00E+08
1.00E+10
1.00E+12
0.1 1 10 100
exposure time (days)
|Z|
(Oh
m)
black CHM 0.5
black EIS 0.5
Comparisson CHM - EIS
coating 2
1.00E+02
1.00E+04
1.00E+06
1.00E+08
1.00E+10
1.00E+12
0.1 1 10 100 1000
exposure time (days)
|Z|
(Oh
m)
white CHM 0.5
white EIS 0.5
Comparisson CHM - EIS
coating 3
1.00E+02
1.00E+04
1.00E+06
1.00E+08
1.00E+10
1.00E+12
0.1 1 10 100 1000
exposure time (days)
|Z|
(Oh
m)
brown CHM 0.5
brown EIS 0.5
Conclusions so far
The coating degradation sensor is capable of detecting
coating degradation
The actual measurement values are not equal to standard
lab-EIS measurements
Issues that need to be examined:
Electrode tape and adhesion to the coating
Influence of tape on coating degradation
Influence of wetness of the coating
Sensor robustness (i.e. under water installation of sensor)
Battery life
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Microbiological activity sensor
What is microbiological influenced corrosion (MIC)?
Experiment with sensor in artificial sea water
Experiment with sensor in natural sea water and sediment
Experiment with mini mono pile
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What is MIC?
Corrosion initiated or accelerated by micro-organisms
either directly by their metabolic activities or indirectly by
excretion of chemically reactive products.
It has been estimated that as many as 30% of all serious
corrosion events in the industry are influenced by
microbiological activity.
MIC can occur in any system where water is present.
Offshore constructions, piping, ballast tanks, sprinkler
systems.
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When MIC can occur?
Substrate host location to attach
Water no water no MIC
Nutrient no nutrient bacteria can stay in dormant
phase
Oxygen certain types of bacteria need only very small
amounts or no oxygen
More than 99 percent of all bacteria live in biofilm communities
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Microorganisms causing MIC
MIC
Fungi
Methanogens
Organic Acid
Producing Bacteria
Slime Forming
Bacteria
Sulphate Reducing
Bacteria (SRB)
Acid Producing Bacteria (APB)/
Sulphur Oxidising Bacteria (SOB)
Iron/Manganese Oxidising Bacteria (IOB)
Metal-Depositing Bacteria (MDB)
Metal-Reducing
Bacteria (MRB)
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Set-up using Biofilm sensor Experiment-I
Corrosion
coupons
BIOSENSOR
Platinum
electrode
(Redox)
Steel
electrodes
(OCP)
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Experiment I
Artificial sea water, after one week aerobic pseudomona
fluorensens bacteria added
Low sensor signal, redox potential stable, biofilm on
coupons
Anaerobic condition, after 3 weeks Sulphate Reducing
Bacteria (SRB’s) added
Sensor signal up after 2-3 days, redox potential starts
decreasing, when nutrients were consumed, signal
became low
Addition of oxygen by stirring
Reduced SRB activity, Sensor signal low
Anaerobic condition, addition of SRB’s and abundant
nutrients
Sensor signal high
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Set-up using Biofilm sensor Experiment-II
Sediment Natural seawater
BIOSENSOR
OCP measurement Corrosion Coupons
Small minipile
section
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Experiment-II
Natural sea water with sediment, stagnant condition
Development of biofilm, growth tests revealed bacteria
on steel samples, biosensor signal high, after 1 month
activity decreased
3 months later, stagnant condition
Growth tests revealed bacteria, biosensor signal low
and fluctuation. Possible low activity due to lack of nutriens
Nutients were added
Biosensor signal increased and redox potential
dropped. Increased biological activity caused the sensor to
give a higher signal
The redox potential does not influence the sensor signal
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Current plans - Field experiment An experimental set-up that will simulate real-life conditions as closely as
possible, whilst allowing the manipulation of environmental factors)
•Large monopile (already in-house)
•Underwater pH, Oxygen, Salinity, Temp
electrodes (in-house; all continuous
monitoring)
•Redox electrode
•Corrosion coupons
•MIC test kits (SRB and APB)
•Compound electrodes (for OCP
measurements)
•Noise measurement (to check pitting
initiation)
•BIOSENSOR I & 2
•Coating health sensors on outer wall
Get Organised
For effective asset integrity management accurate information
is indispensible
High quality asset inspection data can lead to a cost effective
maintenance program
With a solid maintenance program high cost downtime and
unexpected repair can be prevented
Asset integrity: Design, Inspection, Maintenance