Think Simulation! Adventures in Electrolytes. Corrosion Simulation. October 17, 2012

Transcription

1 Think Simulation! Adventures in Electrolytes Corrosion Simulation October 17, 2012 OLI Simulation Conference 2012

2 Scope Review of corrosion simulation models Progress in modeling general corrosion: Cu-Ni alloys Progress in modeling localized corrosion Progress in extreme value statistics Plans for future development

3 General and localized corrosion models Electrochemistry of metal solution interface AQ and MSE thermodynamic models + stability diagrams Chemistry / corrosion thermodynamics OLI corrosion technology Probabilistic aspects of propagation Extreme value statistics Corrosion Simulation: Structure Single-phase flow and integration with multiphase flow data Fluid flow effects Cr / Mo grain boundary depletion model Alloy microstructure effects Reactive transport / propagation of localized phenomena Standalone models for crevice corrosion, SCC, corrosion fatigue (not in CA)

4 Electrochemical model of general corrosion Synthesis of electrochemical phenomena using mixedpotential theory Generation of model polarization curves to simulate Partial electrochemical processes Cathodic reactions reduction of solution species Anodic reactions - oxidation of metals Effect of complexation Adsorption phenomena Passive dissolution and active-passive transition Effect of solution species on passive dissolution Effect of flow conditions on cathodic and anodic processes Transport of reactive species to the interface Transport of corrosion products away from the interface

5 Behavior of recently added alloys: Corrosion rate of Cu-Ni alloys 10 1 Efird and Anderson (1975) K, ph , quiescent, 5-14 years Efird and Anderson (1975) K, ph , flow ing 0.6 m/s, 5-14 years Efird and Anderson (1975) K, ph , tidal, 5-14 years Int. Nickel Co. 298 K, tidal 0.3 m/s Corr. Rate (mm/y) Mansfeld et al. (1994) 298 K, days, aerated Efird (1977) 298 K, ph 8, quiescent, 2 years Efird (1977) 298 K, ph 8, flow ing 0.5 m/s, 2 years Todd (1986) 298 K, flow ing m/s Todd (1986) 298 K, flow ing m/s Gudas and Hack (1979) 298 K, ph 8, flow ing m/s, 15 days Syrett and Macdonald (1979) 299 K, flow ing 1.62 m/s m O2 Schleich (2004), static Todd (1986) 378 K, flow ing 8 ft/s Calc, 298K, static Calc, 298K, pipe flow, 2 cm, 0.6 m/s Calc, 298K, pipe flow, 2 cm, 1.6 m/s CuNi9010 in seawater Availability of oxygen controls corrosivity Rates are low but flow effects are substantial Thermodynamic analysis yields insights into corrosion behavior

6 Thermodynamic interpretation of corrosion behavior of Cu-Ni alloys Passivity is dominated by Cu oxides; Ni does not extend the passivity range in acidic solutions. However, presence of Ni influences the stability of passive film Anodic behavior in the active state in a wide range of ph Hydrogen reduction lies in the immunity zone: oxidants are necessary to cause corrosion sea water ph

7 CuNi9010 in seawater: corrosion potential 0.30 Efird (1975) K, ph , stirred Efird (1975) 294 K, ph 10.1, stirred Ecorr, V / SHE Macdonald et al. (1978) 295 K, ph 8-8.4, flow ing 1.62 m/s, deoxygenated Little and Mansfeld (1991) 298 K, static, aerated, 19 w eeks Beccaria and Crousier (1989) 298 K, ph 8, unstirred Efird (1975) 298 K, ph 4.5, stirred Efird (1975) 298 K, ph 3-8.7, stirred Effird (1977) 298 K, ph 8, flow ing 0.5 m/s, 2 months Gudas and Hack (1979) 298 K, ph 8, flow ing m/s, 2 months Macdonald et al. (1978) 299 K, ph , 1.62 m/s flow Calc, 298K, static Calc, 298K, pipe flow, 2 cm, 0.6 m/s m O2 Calc, 298K, pipe flow, 2 cm, 1.6 m/s E corr depends strongly on oxygen concentration As with corrosion rates, flow effects are substantial

8 Effect of dissolved oxygen: Polarization curve illustrates mechanism static 10-6 m O m O 2 Oxygen is the dominant cathodic process O 2 concentration increases corrosion rate and potential Effect of oxygen will plateau once passive current density limit is reached

9 CuNi9010 in seawater: corrosion rate as a function of flow rate Corr. Rate (mm/y) Syrett and Wing (1980) K, ph , 9-11 days, pipe 1.35cm diameter, 6.6 ppm O2, 9-11 days Cohen and George (1974) 394 K, natural treated, 0 ppm O2, 54 months Cohen and Whitted (1971) 394 K, natural treated, < ppm O2, 697 days Cohen and Rice (1970) 394 K, natural treated, ppm O2, days Cohen and Rice (1970) 394 K, natural treated, ppm O2, 365 days, butt w elded Calc, 298 K, pipe 1.35 cm, 6.6 ppm O2 Calc, 394 K, pipe cm, ph=7.4, ppm O Flow rate (m/s) Calc, 394 K, pipe cm, ph=7.4, ppm O2 Strong effect of flow at low dissolved oxygen Corrosion at conditions related to desalination

10 Effect of velocity: Interpretation using polarization curves 0 m/s 0.1 m/s 6 m/s Anodic current increases with flow velocity due to the Cl-mediated dissolution mechanism This increases corrosion rate and reduces corrosion potential

11 Effect of sulfides on CuNi m H 2 S Thermodynamic aspects Formation of sulfides at potentials much lower than Me/Me 2+ potentials This has a profound effect on anodic dissolution

12 V / SHE V / SHE E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E m S(-2) CuNi9010 Syrett and Wing (1980) K, ph , 230 h, pipes, 1.35cm diameter, 3-5 m/s, deaerated Macdonald et al. (1978) 295 K, ph 8-8.4, flowing 1.62 m/s, h, deoxygenated Eiselstein et al. (1983) 296 K, ph , tubes 3 m/s, aerated, 16 days Eiselstein et al. (1983) 296 K, ph , tubes 3 m/s, ppm O2, 4 days Eiselstein et al. (1983) 296 K, ph , tubes 3 m/s, deaerated, 4 days Gudas and Hack (1979) 298 K, ph 8, flowing m/s, aerated, 1-60 days days Syrett et al. (1979) 298 K, natural seawater, ppm O2, aerated Calc, pipe 1.35cm, 3 m/s, 0.05ppm O2 Calc, pipe 1.35cm, 1.62 m/s, 0.05ppm O2 Calc, static, 0.2ppm O2 Calc, static, aerated E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 m S(-2) CuNi7030 Alhajji and Reda (1993b) 293 K, aerated, quiescent Alhajji and Reda (1993b) 293 K, aerated, stirred Alhajji and Reda (1993a) 293 K, aerated, quiescent Alhajji and Reda (1993a) 293 K, aerated, stirred Alhajji and Reda (1995) 293 K, deaerated, quiescent Reda and Alhajji (1993) 293 K, aerated, quiescent Alhajji and Reda (1994) 293 K, aerated, jet impingement 298 K, seawater, aerated, static 298 K, seawater, aerated, RDE 1000 rpm 298 K, seawater, 0.1 ppm O2, static CuNi7030 and CuNi9010 in seawater with sulfides Strong decrease of corrosion potential as a function of sulfides Data are scattered because multiple steady states are possible in the transition region

13 Corr. Rate (mm/y) Corr. Rate (mm/y) 1 CuNi ph CuNi7030 Caruso and Michels (1981) 294 K, 0.12 m NH3, spray test, air Polan et al. (1981) 298 K, m NH3, aerated, 8-12 ppm O2 Polan et al. (1981) 298 K, m NH3, deaerated, ppm O2 Sheldon and Polan (1985) 298 K, m NH3, lab. data, deaerated Caruso and Michels (1981) 303 K, m NH3, fog test, air Todd (2005), 500 ppm NH3, 1400 ppm NH4CO3 Calc, 298K, NH3, 10 ppm O2, static Calc, 298K, NH3, 0.2 ppm O2, static Calc, 298 K, 1400ppm NH42CO3+NH3, air, static Caruso and Michels (1981) 294 K, 0.12 m NH3, spray test, air Polan et al. (1981) 298 K, m NH3, aerated, 8-12 ppm O2 Polan et al. (1981) 298 K, m NH3, deaerated, ppm O2 Sheldon and Polan (1985) 298 K, m NH3, lab. data, deaerated Caruso and Michels (1981) 303 K, m NH3, fog test, air Todd (2005), 500 ppm NH3, 1400 ppm NH4CO3 298K, NH3, 10 ppm O2, static 298K, NH3, 0.2 ppm O2, static Effect of ammonia: CuNi7030 and CuNi9010 Complexation of Cu with NH 3 leads to enhanced anodic dissolution Role of dissolved O 2 is important CuNi7030 is more resistant to ammonia corrosion Higher Ni content mitigates dissolution ph 298 K, 1400ppm NH42CO3+NH3, air, static

14 Assessment of corrosion resistance Example: Alloy 2205 in H 2 SO 4 Isocorrosion Curve (0.1 mm/y) General Corrosion Hummel (1982) T, 0 C No General Corrosion Nicolio and Courtis (2002) Calculations H2SO4, m

15 Prediction of localized corrosion Criterion: Corrosion potential vs. repassivation potential Potential E rp Chloride Repassivation potential model Interfaces: Metal metal halide occluded solution Formation of metal oxide in the limit of repassivation Competitive adsorption at the interface Aggressive ions promoting metal dissolution Inhibitive ions promoting oxide formation Ecorr Localized corrosion

16 Previous work: Generalized correlation for predicting E rp of Fe-Ni-Cr-Mo-W-N alloys Erp(SHE) a Cl 22, exp 22, generalized 276, exp 276, generalized 625, exp 625, generalized 825, exp 825, generalized 690, generalized 600, exp 600, generalized 800, generalized 254SMO, exp 254SMO, generalized AL6XN, exp AL6XN, generalized 2205, generalized 316L, exp 316L, generalized 304L, generalized s-13cr, exp s-13cr, generalized Reproduces E rp for 15 metals (13 stainless steels and nickel-base alloys, Ni, and Fe) Predictions have been verified from 296 K to 423 K Example: T = 368 K

17 Alloy 2507 in chloride solutions at 85 C: Blind test Erp, SHE no localized corrosion observed - points ignored m Cl - No H2S, Sept 2012 No H2S, Feb 2012 Calc (correlation) Calc (one parameter adjusted) The generalized correlation predicts E rp that is very close to the most recent experimental data Further improvement is obtained by a slight adjustment of the Gibbs energy of activation for metal dissolution mediated by adsorption of Cl - ions

18 Localized corrosion: Current work Localized corrosion in Cl - - H 2 S environments Stress corrosion cracking: Initiation above E rp Extension of the model to include H 2 S effects Experimental program at DNV

19 Generalization to multiphase flow Electrochemical reactions depend on the concentrations of species near the surface Mass transfer of species to and from the interface depends on flow conditions Numerical characterization through mass transfer coefficient k m Models for calculating k m for single-phase flow have been available in the Corrosion Analyzer In multiphase flow, there is a great variability of flow patterns and a generalized approach is necessary

20 Generalization to multiphase flow: Shear stress Shear stress yields mass transfer coefficient k m : k m shear stress 2/3 0 D Alternative ways of calculating the shear stress From fluid flow software Preferred approach because it can account in detail for various flow patterns Integration with OLGA From an approximate correlation for water oil gas flow

21 Electrochemical models for general and localized corrosion: Parameterization Metals Carbon steel Stainless steels: 13Cr, 304, 316, 254SMO Nickel-base alloys: 22, 276, 625, 825, 600, 690, and Ni Duplex alloy: 2205 Copper-nickel alloys: Cu, CuNi9010, CuNi7030 Aluminum

22 Progress in Extreme Value Statistics Objective: Predict the propagation of localized corrosion as a function of time on the basis of shortterm data From current EVS Analyzer

23 Progress in Extreme Value Statistics New developments Improved statistics: Calculating the upper bound for localized corrosion Prediction of the number of perforations, their area and leak rate Extension to r-largest order statistics Number of holes per sq. ft /2 in. 1/4 in Time, years Predicting the number of penetrations as a function of time for varying wall thickness

24 Plans for Future Development Short and medium-term objectives Implementation of improvements to Extreme Value Statistics in Corrosion Analyzer Corrosion-resistant alloys in oil and gas environments (in collaboration with DNV) Long-term objective Mixed-solvent electrolyte electrochemical model Opening new chemistries and providing improved predictions by taking advantage of the MSE thermodynamic model