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.

2

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

5

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

6

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

7

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.

8

Water capacity layers (from 0cm to 1.20cm)

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

10

Analysis of information, Math-computer

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

Water Uptake process-initiation of degradation

Coating Electrolyte Metal

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

Statistical Approach

Time constant , t=70days

Time dependent

Capacitor vs. time

ClepHeteEceeZeqi 111011984.922.545.162.2119.1

Red dots observed Circle fitted

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

18

Electrochemical testing –Micro and submetric scale

Constant Immersion

19

Metric scale

20

Macro scale –real scale validation of the laboratory and theoretical approach

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

22

•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)