Corrosion/damage assessment for coating/substrate ... underground pipelines Interfaces ... Three...
Transcript of Corrosion/damage assessment for coating/substrate ... underground pipelines Interfaces ... Three...
Corrosion/damage assessment for coating/substrate underground pipelines
Interfaces (Defining a failure vs. risk vs. reliability with
multiscale concept)
National Center for Corrosion Research and Education Chemical and Biomolecular Engineering
Corrosion Forum
Homero Castaneda, Ph.D.
Overview • Liquid Oil & Gas - Pipelines have been the preferred mode of
transportation over competing modes such as road and rail for several reasons: – they are less damaging to the environment, – less susceptible to theft, and – more economical, safe, convenient, and reliable than other
modes.
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Three different threats are identified in buried systems ASME B31.8S – 2004 : Static (materials and construction) Time independent (third party, external damage) Time-dependent (IC, EC, SCC) corrosion is considered in each one
Time
Cl-
Cl-
Cl-
O2 Cl-
Cl-
Stage I Stage II Stage III Stage IV
Initiation Coating/damage
Transition
Grow/dissolution
Metal damage
New concept: Damage evolution for organic
coating/substrate
Definition of a failure vs. risk vs. reliability
O2
O2
Hours-days-years Hours-years Days-years Days-years
Why multi-scale analysis?
Large scale • Monitoring tools • Damage evaluation • Life time prediction • Integrity and reliability
Small scale • Transport mechanisms • Characterization tools • Random nature of the system
Hepel, Electrochimica Acta (2006), 5811-5824
Castaneda et al, Journal of Solid State Electrochemistry, 2005, 9, 535-546.
From www.ELSYCA.com web site
Example of application: Adaptation and enhancement of the technologies used for corrosion management for Mexican pipeline system Includes multiscale analysis for external corrosion, electrolyte/coating/metal
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Motivation Integrity Management for Pipeline Network
On shore Pipeline Network: ~*65, 000 km total Off shore Pipelines >100,000 km Gulf of Mexico and will be more >100 new platforms
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Mexico is the 3rd crude provider to US Canada is 1st http://www.eia.doe.gov
Adaptation of Step 1 Mathematical modeling for the electrolyte(soil)/interface(coating)/pipe
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0.0
50.0
100.0
150.0
200.0
250.0
Jan Feb Mar Apr May June July Aug Sep Oct Nov Dec
Month of the year
avera
ge m
agnitu
des in
mm
pre
cip
itatio
n
during 8
6 y
ears
Macro tools
Location of the system is important due to climate, geographical and global position of the pipeline section. Electrolyte properties.
9 0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
0 20 40 60 80 100 120
Ioni
c con
cent
rati
on(m
mol
/L)
Distance (km)
pH
CO3=
HCO3-
Cl-
SO4=
Macromodeling-micromodeling
States of the Coating/Steel
Initiation stage-water uptake
Most models assume the damage function of the metal or the pre-existence of coating damage.
time
Impedance Results with Time for Initiation
-1e7 0 1e7 2e7 3e7
-4e7
-3e7
-2e7
-1e7
0
Z'
Z''
1EISC5z.z2EISC5z.z3EISC5z.z4EISC5z.z5EISC5z.z6EISC5z.z7EISC5z.z8EISC5z.z9EISC5z.z10EISC5z.z
NS3 solution, pH=5.8 after 70 days of exposure
Deterministic Analysis to determine the initiation/growth threshold
NS4 solution
-0.05
0
0.05
0.1
0.15
0.2
0.25
0 10 20 30 40 50 60 70 80
time (days)
wa
ter
up
take
fa
cto
r (p
hi) pH-10.3
pH-7.0
pH-5.8
NS3 solution
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0 10 20 30 40 50 60 70 80
Time (days)
wate
r u
pta
ke f
acto
r (p
hi)
pH-10.3
pH-7.0
pH-5.8
Capacitor /water uptake with time
80
/)(log CotC
Electrochemical set up for different conditions
Constant immersion Cycling conditions w/o environmental
parameters
Fog or artificial chamber-design in construction with different % RH and wetness time
Wetting characteristics
Reliability engineering in different corrosive environments failure definition
30 um thickness, pH=5 60 um thickness, pH=5 100 um Thickness, pH=5
Damage depth at the metal-Damage of the system Simulation
Topics for unification in corrosion science and engineering in substrate/coatings assessment
for underground pipelines
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•Complementary or new testing for damage evolution for coating/substrate system •In situ sensing (real time monitoring) •Deterministic and stochastic –probabilistic modeling •Multiscale modeling (macro-scale to nano scale) •Characterization tools for coatings •Reliability (failure defined in terms of mathematical, physical or standard criteria)