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Corrosion Modeling Software and Corrosion Prediction Software Series 

GC-Compass®: A Software Tool for Galvanic Corrosion Prediction and Materials Compatibility Assessment

The Ultimate Software Solution to Costly Galvanic Corrosion

Version 9.20


      Performance        Functionality        Usability

Anytime       Anywhere      Any Device      Any OS

No USB dongles     No installation       No Browser Plug-ins


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Why WebCorr | Performance Guarantee | Unparalleled Functionality | Unmatched Usability | Any Device Any OS | Free Training & Support | CorrCompass

Overview and Application Examples of GC-Compass:
Software Tool for Galvanic Corrosion Prediction and Materials Compatibility Assessment

GC-Compass is the only device and OS independent software tool on the market for the prediction of galvanic corrosion and assessment of materials galvanic compatibility. Designers, engineers, architects, consultants, or maintenance and inspection personnel can quickly assess and quantify the impact of galvanic coupling of dissimilar metals on the remaining life of their components or systems anytime, anywhere, on any device running any OS without the need to install or download anything.


The NACE/ASTM G193 standard defines corrosion as "the deterioration of a material, usually a metal, that results from a chemical or electrochemical reaction with its environment."

From the standard definition of corrosion above, it is clear that the environment plays a critical role in all types of corrosion including galvanic corrosion. At the design stage, the design engineer has options in materials selection to avoid corrosion of the equipment or structure in a specified service environment. At the operating or in-service stage, the operator has the option to monitor the changes in the service environment (e.g. temperature) that affects corrosion including galvanic corrosion.

GC-Compass is an essential software tool for design engineers and facility owners and operators for modeling and prediction of galvanic corrosion and assessment of material compatibility in actual service environments. Unlike other galvanic corrosion prediction software based on the static "curve crossing" methodology valid only for the controlled laboratory conditions under which the polarization curves were measured for a very limited number of alloys in artificial seawater at 25°C, GC-Compass utilizes machine learning and cloud computing to accurately model the effects of temperature, cathode to anode area ratio, the service environment variables (sea water, 3.5%NaCl solutions, fresh water, tap water, distilled water, marine atmosphere, industrial atmosphere) on the rate of galvanic corrosion and material compatibility for over 500 metal-to-metal and metal-to-CFRP composite galvanic couples.


Input parameters in GC-Compass include:

  • the anode-cathode galvanic couple

  • the service environment

  • the cathode-to-anode area ratio

  • the effective anode thickness

GC-Compass models the effects of the above input parameters and predicts the following:

  • the galvanic current in µA/cm2

  • the galvanic corrosion rate in mm/y

  • the galvanic factor

  • the anode remaining life in years

  • the anode self-corrosion current  in µA/cm2

  • the anode self-corrosion rate in mm/y

  • the material compatibility class

  • polarity reversal for certain galvanic couples when service temperature exceeds certain thresholds.

Users of GC-Compass start by selecting the dissimilar metal couple from the dropdown list. The database has over 500 galvanic couples and is updated regularly with more couples added to the list. Figures below show the screenshots of GC-Compass.


Figure 1 GC-Compass Predicts Galvanic Corrosion Rate and Galvanic Compatibility Class for over 500 Metals, Alloys and CFRP Composite Materials.


The current database includes the following metals, alloys, and CFRP composite galvanic couples:

Ag - Au
Ag - Pt
Al - Ag
Al - Au
Al - Cd
Al - Cu
Al - Brass
Al - Bronze
Al - Hastelloy C
Al - Monel
Al - Ni
Al - Pt
Al - Sn
Al - Ti
Al - AA2024
AA1100 - AISI4130
AA1100 - AISI4340
AA1100 - A286
AA1100 - Carbon Steel
AA1100 - Ag
AA1100 - AA2024
AA1100 - AA2050
AA1100 - AA2060
AA1100 - AA2219
AA1100 - AA5083
AA1100 - AA6061
AA1100 - AA7075
AA1100 - Cd
AA1100 - Cu
AA1100 - Brass
AA1100 - Bronze
AA1100 - M-Bronze
AA1100 - Naval Brass
AA1100 - Admiralty Brass
AA1100 - Muntz Metal
AA1100 - Aluminium Brass
AA1100 - Nickel-Aluminium-Bronze
AA1100 - Tungum Alloy
AA1100 - Cu70Ni30
AA1100 - Cu90Ni10
AA1100 - Monel
AA1100 - Haynes188
AA1100 - Inco718
AA1100 - Ni
AA1100 - Electroless Nickel Plating
AA1100 - 13-8PH
AA1100 - Sn
AA1100 - SS301
AA1100 - SS304L
AA1100 - SS316
AA1100 - SS347
AA1100 - Ti-CP-TA2
AA1100 - Ti6Al4V
AA1100 - Carbon Fibre Composite
AA2024 - AISI4130
AA2024 - AISI4340
AA2024 - 18Ni Maraging Steel 250
AA2024 - A286
AA2024(Cr3+) - A286
AA2024(Cr6+) - A286
AA2024(Anodized_II_Unsealed) - A286
AA2024(Anodized_II_Sealed) - A286
AA2024(Anodized_IIB_Unsealed) - A286
AA2024(Anodized_IIB_Sealed) - A286
AA2024 - Carbon Steel
AA2024 - Ag
AA2024 - AA2219
AA2024 - AA2060
AA2024 - CFRP
AA2024 - Cd
AA2024 - Cu
AA2024 - Brass
AA2024 - Bronze
AA2024 - M-Bronze
AA2024 - Naval Brass
AA2024 - Admiralty Brass
AA2024 - Muntz Metal
AA2024 - Aluminium Brass
AA2024 - Nickel-Aluminium-Bronze
AA2024 - Tungum Alloy
AA2024 - Cu70Ni30
AA2024 - Cu90Ni10
AA2024 - Monel
AA2024 - Haynes188
AA2024 - Inco718
AA2024 - Inconel625
AA2024 - Ni
AA2024 - Electroless Nickel Plating
AA2024 - 13-8PH
AA2024(Cr3+) - 13-8PH
AA2024(Cr6+) - 13-8PH
AA2024(Anodized_II_Unsealed) - 13-8PH
AA2024(Anodized_II_Sealed) - 13-8PH
AA2024(Anodized_IIB_Unsealed) - 13-8PH
AA2024(Anodized_IIB_Sealed) - 13-8PH
AA2024 - 13-8PH (passivated)
AA2024(Cr3+) - 13-8PH(passivated)
AA2024(Cr6+) - 13-8PH(passivated)
AA2024(Anodized_II_Unsealed) - 13-8PH(passivated)
AA2024(Anodized_II_Sealed) - 13-8PH(passivated)
AA2024(Anodized_IIB_Unsealed) - 13-8PH(passivated)
AA2024(Anodized_IIB_Sealed) - 13-8PH(passivated)
AA2024 - 15-5PH
AA2024 - 17-4PH
AA2024 - Sn
AA2024 - SS301
AA2024 - SS304L
AA2024 - SS316
AA2024 - SS347
AA2024 - Ti-CP-TA2
AA2024 - Ti6Al4V
AA2024 - Carbon Fibre Composite
AA2024-Ti6Al4V (0.05M NaCl)
AA2024(Cr3+) - Ti6Al4V
AA2024(Cr6+) - Ti6Al4V
AA2024(Anodized_II_Unsealed) - Ti6Al4V
AA2024(Anodized_II_Sealed) - Ti6Al4V
AA2024(Anodized_IIB_Unsealed) - Ti6Al4V
AA2024(Anodized_IIB_Sealed) - Ti6Al4V
AA2050 - AISI4130
AA2050 - AISI4340
AA2050 - 18Ni Maraging Steel 250
AA2050 - Cd
AA2050 - AA2024
AA2050 - AA2060
AA2050 - Cu
AA2050 - Brass
AA2050 - Bronze
AA2050 - M-Bronze
AA2050 - Naval Brass
AA2050 - Admiralty Brass
AA2050 - Muntz Metal
AA2050 - Aluminium Brass
AA2050 - Nickel-Aluminium-Bronze
AA2050 - Tungum Alloy
AA2050 - Cu70Ni30
AA2050 - Cu90Ni10
AA2050 - Electroless Nickel Plating
AA2050 - Monel
AA2050 - 13-8PH
AA2050 - 13-8PH (passivated)
AA2050 - 17-4PH
AA2050 - SS304
AA2050 - SS316
AA2050 - Ti-CP-TA2
AA2050 - Inconel625
AA2050 - Carbon Fibre Composite
AA2060 - Cd
AA2195 - Cd
AA2195 - AISI4130
AA2195 - AISI4340
AA2195 - 18Ni Maraging Steel 250
AA2195 - Electroless Nickel Plating
AA2195 - A286
AA2195 - AA2024
AA2195 - AA2050
AA2195 - AA2060
AA2195 - Ti-CP-TA2
AA2195 - Carbon Fibre Composite
AA2219 - AISI4130
AA2219 - A286
AA2219 - Carbon Steel
AA2219 - Ag
AA2219 - Cu
AA2219 - Brass
AA2219 - Bronze
AA2219 - Haynes188
AA2219 - Inco718
AA2219 - Ni
AA2219 - 13-8PH
AA2219 - 15-5PH
AA2219 - Sn
AA2219 - SS301
AA2219 - SS304L
AA2219 - SS316
AA2219 - SS347
AA2219 - Ti6Al4V
AA5083 - AISI4130
AA5083 - AISI4340
AA5083 - 18Ni Maraging Steel 250
AA5083 - AA2024
AA5083 - AA2060
AA5083 - AA2195
AA5083 - Cd
AA5083 - Cu
AA5083 - Brass
AA5083 - Bronze
AA5083 - M-Bronze
AA5083 - Naval Brass
AA5083 - Admiralty Brass
AA5083 - Muntz Metal
AA5083 - Aluminium Brass
AA5083 - Nickel-Aluminium-Bronze
AA5083 - Tungum Alloy
AA5083 - Cu70Ni30
AA5083 - Cu90Ni10
AA5083 - Electroless Nickel Plating
AA5083 - Monel
AA5083 - CFRP
AA5083 - 13-8PH
AA5083 - 13-8PH (passivated)
AA5083 - 17-4PH
AA5083 - SS304
AA5083 - SS316
AA5083 - DSS2205
AA5083 - DSS2304
AA5083 - DSS2507
AA5083 - Ti-CP-TA2
AA5083 - Inconel625
AA5083 - Carbon Fibre Composite
AA6061 - AISI4130
AA6061 - AISI4340
AA6061 - 18Ni Maraging Steel 250
AA6061 - A286
AA6061 - AA1100
AA6061 - AA2024
AA6061 - AA2060
AA6061 - AA2195
AA6061 - AA2219
AA6061 - Carbon Steel
AA6061 - A848 (magnetic iron)
AA6061 - A36
AA6061 - Anodized AA6061
AA6061 - Cd
AA6061 - Cu
Anodized AA6061 - Cu
AA6061 - Brass
AA6061 - Bronze
AA6061 - M-Bronze
AA6061 - Naval Brass
AA6061 - Admiralty Brass
AA6061 - Muntz Metal
AA6061 - Aluminium Brass
AA6061 - Nickel-Aluminium-Bronze
AA6061 - Tungum Alloy
AA6061 - Cu70Ni30
AA6061 - Cu90Ni10
AA6061 - Monel
Anodized AA6061 - Monel
AA6061 - CFRP
AA6061 - Haynes188
AA6061 - Inco718
AA6061 - Inconel625
Anodized AA6061 - Inconel625
AA6061 - Ni
AA6061 - Electroless Nickel Plating
AA6061 - 13-8PH
AA6061 - 13-8PH (passivated)
AA6061 - 15-5PH
AA6061 - 17-4PH
AA6061 - Sn
AA6061 - SS301
AA6061 - SS304L
AA6061 - SS316
AA6061 - SS347
AA6061 - Ti6Al4V
AA6061 - Ti-CP-TA2
AA6061 - Ag
AA6061 - Carbon Fibre Composite
AA7050 - AA2024
AA7050 - AA2195
AA7050 - AA2060
AA7050 - Carbon Steel
AA7050 - AISI4130
AA7050 - AISI4340
AA7050 - 18Ni Maraging Steel 250
AA7050 - Cd
AA7050 - Cu
AA7050 - Brass
AA7050 - Bronze
AA7050 - M-Bronze
AA7050 - Naval Brass
AA7050 - Admiralty Brass
AA7050 - Muntz Metal
AA7050 - Aluminium Brass
AA7050 - Nickel-Aluminium-Bronze
AA7050 - Cu70Ni30
AA7050 - Cu90Ni10
AA7050 - Monel
AA7050 - Carbon Fibre Composite
AA7050 Anodized - Carbon Fibre Composite
AA7050 Anodized - AA2060
AA7050 - Electroless Nickel Plating
AA7050 - SS316
AA7050 - 17-4PH
AA7050 - Ti-CP-TA2
AA7050 - Ti6Al4V
AA7050 Anodized - Ti6Al4V
AA7050 - Ti-3Al-2.5V
AA7050 Anodized - Ti-3Al-2.5V
AA7075 - AISI4130
AA7075 - AISI4340
AA7075 - 18Ni Maraging Steel 250
AA7075 - A286
AA7075 - Carbon Steel
AA7075 - HY-80 Steel
AA7075 - Ag
AA7075 - AA2024
AA7075 - AA2195
AA7075 - AA2219
AA7075 - AA6061
AA7075 - Cu
AA7075 - Brass
AA7075 - Bronze
AA7075 - M-Bronze
AA7075 - Naval Brass
AA7075 - Admiralty Brass
AA7075 - Muntz Metal
AA7075 - Aluminium Brass
AA7075 - Nickel-Aluminium-Bronze
AA7075 - Cu70Ni30
AA7075 - Cu90Ni10
AA7075 - Monel
AA7075 - Haynes188
AA7075 - Inco718
AA7075 - Inconel625
AA7075 - Ni
AA7075 - Electroless Nickel Plating
AA7075 - 13-8PH
AA7075 - 13-8PH (passivated)
AA7075 - Sn
AA7075 - 15-5PH
AA7075 - 17-4PH
AA7075 - SS301
AA7075 - SS304L
AA7075 - SS316
AA7075 - SS347
AA7075 - Ti-CP-TA2
AA7075 - Ti6Al4V
AA7075 - Carbon Fibre Composite
AA7075 anodized - Carbon Fibre Composite
Carbon Steel - Ag
Carbon Steel - Au
Carbon Steel - Cu
Carbon Steel - Brass
Carbon Steel - Bronze
Carbon Steel - M-Bronze
Carbon Steel - Naval Brass
Carbon Steel - Admiralty Brass
Carbon Steel - Muntz Metal
Carbon Steel - Aluminium Brass
Carbon Steel - Nickel-Aluminium-Bronze
Carbon Steel - Cu70Ni30
Carbon Steel - Cu90Ni10
Carbon Steel - Monel
Carbon Steel - Ni
Carbon Steel - Electroless Ni Plating

Carbon Steel - LHE Zn-Ni Plating
Carbon Steel - Pt
Carbon Steel - 15-5PH
Carbon Steel - SS304
Carbon Steel - SS316
Carbon Steel - DSS2205
Carbon Steel - DSS2304
Carbon Steel - DSS2507
Carbon Steel - DSS2707HD
Carbon Steel - 904L
Carbon Steel - 254SMO
Carbon Steel - Inconel625
Carbon Steel - C276
Carbon Steel - AL-6XN
Carbon Steel - A286
Carbon Steel - AISI4130
Carbon Steel - AISI4340
Carbon Steel - AA2195
AISI4130 - 15-5PH
AISI4130 - Electroless Nickel Plating
AISI4340 - Electroless Nickel Plating
AISI4340 - A286
AISI4340 - AISI4130
Cd - AA7075
Cd - AISI4130
Cd - AISI4340
Cd - Ag
Cd - Au
Cd - Brass
Cd - Bronze
Cd - Cu
Cd - Carbon Steel
Cd - Hastelloy C
Cd - Monel
Cd - Ni
Cd - Electroless Nickel Plating
Cd - Pt
Cd - SS316
Cd - Ti
Brass - Cu
SS304 - Brass
SS304 - M-Bronze
SS304 - Naval Brass
SS304 - Admiralty Brass
SS304 - Muntz Metal
SS304 - Aluminium Brass
SS304 - Nickel-Aluminium-Bronze
SS304 - Cu70Ni30
SS304 - Cu90Ni10
SS304 - Monel
Monel - SS316
Brass - SS316
Brass - A286
C276 - Brass
Brass - DSS2507
Brass - DSS2205
Brass - DSS2304
Brass - 254SMO
Brass - 904L
Brass - Inconel625
Brass - 13-8PH
Brass - 15-5PH
17-4PH - Brass
Brass - Bronze
Brass - Graphite
Bronze - Cu
Bronze - SS304
Bronze - SS316
Bronze - A286
Bronze - C276
Bronze - DSS2507
Bronze - DSS2205
Bronze - DSS2304
Bronze - 254SMO
Bronze - 904L
Bronze - Inconel625
Bronze - 13-8PH
Bronze - 15-5PH
Bronze - 17-4PH
Bronze - Graphite
SS316 - M-Bronze
Naval Brass - SS316
Admiralty Brass - SS316
SS316 - Muntz Metal
SS316 - Aluminium-Brass
Nickel-Aluminium-Bronze - SS316
SS316 - Cu70Ni30
SS316 - Cu90Ni10
Cu - Ag
Cu - Au
Cu - Monel
Cu - Pt
Cu - SS316
Hastelloy C - Ag
Hastelloy C - Au
Hastelloy C - Pt
Mg - Ag
Mg - Al
Mg - Au
Mg - AZ31
Mg - AZ33
Mg - AZ91
Mg - Cd
Mg - Cu
Mg - Brass
Mg - Pb
Mg - Sn
Mg - Ti
Mg - Zn
Monel - Ag
Monel - Au
Monel - Pt
Ni - Ag
Ni - Au
Ni - Pt
Ni - SS316
Pb - Ag
Pb - Au
Pb - Cu
Pb - Brass
Pb - Hastelloy C
Pb - Monel
Pb - Ni
Pb - Pt
Pb - SS316
Pb - Ti
Sn - Ag
Sn - Au
Sn - Cu
Sn - Brass
Sn - Hastelloy C
Sn - Monel
Sn - Ni
Sn - Pt
Sn - SS316
Sn - Ti
SS304 - Ti-CP-TA2
SS316 - Ti-CP-TA2
DSS2205 - Ti-CP-TA2
DSS2304 - Ti-CP-TA2
DSS2507 - Ti-CP-TA2
SS316 - Ag
SS316 - Au
SS316 - Pt
SS316 - AL6XN
13-8PH - Carbon Fibre Composite
13-8PH passivated - Carbon Fibre Composite
904L - 254SMO
904L - AL6XN
SMO254 - Monel
AL6XN - A286
AL6XN - Cu70Ni30
AL6XN - Cu90Ni10
Ti6Al4V - AL-6XN
Ti6Al4V - SS304
Ti6Al4V - SS316
Ti6Al4V - 13-8PH
Ti6Al4V - 15-5PH
Ti6Al4V - A286
Ti6Al4V - Brass
Ti6Al4V - Bronze
Ti6Al4V - Cu
Ti6Al4V - Ti-CP-TA2
Ti6Al4V - Carbon Fibre Composite
Ti-CP-TA2 - Carbon Fibre Composite
Ti - Ag
Ti - Au
Ti - Pt
Zn - Al
Zn - AA1100
Zn - AA2024
Zn - AA5083
Zn - AA6061
Zn - AA7050
Zn - AA7075
Zn - Au
Zn - Cu
Zn - Brass
Zn - M-Bronze
Zn - Naval Brass
Zn - Admiralty Brass
Zn - Muntz Metal
Zn - Aluminium Brass
Zn - Nickel-Aluminium-Bronze
Zn - Cu70Ni30
Zn - Cu90Ni10
Zn - AISI4130
LHE Zn-Ni Plating - AISI4130

Zn - AISI4340
LHE Zn-Ni Plating - AISI4340
Zn - Carbon Steel
Zn - Hastelloy C
Zn - Monel
Zn - Ni
Zn - Electroless Nickel Plating
Zn - Pt
Zn - Sn
Zn - SS304
Zn - SS316
Zn - A286
Zn - Inconel625
Zn - Ti-CP-TA2
Zn - Ti6Al4V

If you cannot find the couple of your interest in the list, do let us know through the Contact Us link and we will conduct the necessary tests to generate the required data for inclusion in the software, free of charge for licensed users of GC-Compass.


Figure 2 GC-Compass Predicts Galvanic Corrosion and Galvanic Compatibility Class for over 400 Metals, Alloys, and CFRP Composite Galvanic Couples.


After selecting the galvanic couple, the next step is to select the environment relevant to your application. The dropdown list in Figure 3 below has 7 options from seawater to industrial atmosphere, representing the natural environments. If your process fluids are not listed in the dropdown menu, you should choose one of the waters that closely matches the chloride level in your process fluids. WebCorr can customize GC-Compass for your specific process fluids and alloys used in any industry from general engineering to wafer fabrication. A customized version of GC-Compass software can be used to monitor galvanic corrosion of your equipment or facilities in real-time.


Figure 3 GC-Compass Models the Effects of Seven Types of Environments on Galvanic Corrosion and Galvanic Compatibility Class.


The next step is to enter the temperature of the environment. Temperature is a critical factor that influences the rate of corrosion. Some galvanic couples such as zinc-steel and aluminium-steel will reverse the polarity at certain temperatures, meaning the usual anodes (zinc and aluminium) have become the cathodes with respect to steel when the temperature exceeds certain threshold value, as shown in Figure 4 below. Note that it is always the anode that suffers accelerated corrosion due to galvanic coupling. GC-Compass is the only software on the market that models the effect of temperature on galvanic corrosion and predicts the polarity reversal when temperature changes.


Figure 4 GC-Compass Predicts the Polarity Reversal for Zinc in Zn-Carbon Steel Couple.


GC-Compass models the effects of temperature and the cathode to anode area ratio on the corrosion rate of the anodic member of the couple and the galvanic compatibility. Other galvanic corrosion prediction software based on the static "curve crossing" methodology simply fail to model the critical effects of temperature and the cathode-to-anode area ratio on the galvanic corrosion rate and galvanic compatibility. The outputs from the GC-Compass software include:

  • the predicted corrosion rate of the anode metal in mm per year (mm/y).

  • the remaining life of the component assembly based on the corrosion rate of the anodic member of the galvanic couple.

  • the galvanic compatibility class based on the quantitative evaluation of the acceleration factor due to galvanic effect. Class I means the materials are galvanically compatible with no significant increase in the corrosion rate of the anode metal; Class II means borderline condition where galvanic corrosion of the anode metal is expected but the acceleration in corrosion is moderate; Class III means the materials are galvanically incompatible in the selected environment at the specified temperature. Severe galvanic effect is expected to cause rapid failure of the anode metal.

  • polarity reversal for certain galvanic couples when service temperature exceeds certain thresholds.


Figure 5 GC-Compass Models the Effects of Temperature and Cathode to Anode Area Ratio on Galvanic Corrosion and Galvanic Compatibility Class.


GC-Compass is not only immensely useful for the prediction of galvanic corrosion and assessment of galvanic compatibility of metals and alloys, it is also equally powerful when used for the prediction of the self-corrosion rate of a single metal when it is not galvanically coupled to another metal.
This can be done by setting the "cathode to anode area ratio" to zero – the anode metal in the selected couple is then effectively corroding independently without the influence of galvanic effect. Now you can change the temperature or the environment and see the predicted remaining life of the anode metal without the influence of galvanic corrosion. This is another unique feature in GC-Compass that is not found in other galvanic corrosion prediction software based on the static "curve crossing" methodology. WebCorr's corrosion prediction software and corrosion modeling software utilize machine learning and cloud computing to optimize the predictive engines such that all contributing factors to the corrosion process are accurately processed. The prediction and modeling results are validated against field data, not the artificial seawater at 25°C used by other software based on the static "curve crossing" methodology.


Service Life Prediction for Fasteners

GC-Compass can be a particularly powerful tool for predicting the performance or service life of fasteners. For example, the SS316 fasteners used on AA6061 plates exposed to seawater at 60°C can be accurately predicted using the "effective thickness of anode". Assuming that the fastening assembly will fail when the hole in the AA6061 plates loses 0.35 mm thickness (or the diameter of the hole increases by 0.70 mm),  GC-Compass predicts that the SS316-AA6061 assembly exposed to seawater at 60°C would fail in just over 5 months (Figure 6a) below.


Figure 6a GC-Compass Predicts the Galvanic Compatibility and the Service Life of Fasteners


Numerous fastener configurations (metallic materials both ferrous and non-ferrous, with metallic coatings such as cadmium, nickel, zinc and galvanizing, and CFRP composites) exposed to seawater, fresh water, tap water, distilled water, marine atmosphere and industrial atmosphere can be assessed and evaluated at the design stage before service failures occur in the fields. For example, Figure 6b shows that aluminum alloy AA7075 is compatible with titanium alloy Ti-6Al-4V exposed to marine environment at 25°C. No significant galvanic effect is expected under the specified conditions. However, when the temperature is increased by 10°C to 35°C which is entirely expected in military aircrafts operating in many parts of the world, the compatibility class shifted to Class II: borderline condition with significant galvanic corrosion rate at 0.15 mm/y, as shown in Figure 6c. Other galvanic corrosion prediction software based on the static "curve crossing" methodology simply fails to model this critical effect of temperature on the galvanic compatibility.


Figure 6b GC Compass Predicts the Compatibility of AA7075 with Ti-6Al-4V Fasteners


Figure 6c GC-Compass Models the Critical Effect of Temperature on the Galvanic Compatibility of Fasteners


Service Life Prediction for Process Piping in Semiconductor Manufacturing

In semiconductor manufacturing, the process cooling water is frequently contaminated with copper ions, which will deposit on aluminum alloy AA6061 piping surface and induce pitting corrosion in aluminium AA6061. The temperature of the process cooling water is about 90°C and the pipe wall thickness is 2.85 mm. The first leak in the piping was reported after 850 days in operation. Tap water in GC-Compass closely matches the chloride level in the process cooling water. With this basic information (Figure 7), GC-Compass predicts that the piping would leak in approximately 2.334 years after operation due to the galvanic effect of AA6061 and the copper deposit. Other galvanic corrosion prediction software based on the static "curve crossing" methodology simply fail to model the critical effects of temperature and service environment on the galvanic compatibility and the remaining life.


Figure 7 GC-Compass Predicts Service Life of Process Piping in Semiconductor Manufacturing.


Service Life Prediction for Structures in Marine and Seawater Services

AA6061 plate and carbon steel structural members were used for the construction of a vessel for seawater services. The effective cathode to anode area ratio is 11.04. The vessel leaked just over 2 years after commencing operation. The galvanic compatibility between AA6061 and carbon steel predicted by GC-Compass is Class III, which means the two materials are not compatible in the seawater environment, and the time-to-leak predicted by GC-Compass is 2.11 years (Figure 8). Other galvanic corrosion prediction software based on the static "curve crossing" methodology simply fail to model this critical effect of cathode to anode area ratio on the galvanic corrosion rate and galvanic compatibility in seawater.


Figure 8 GC-Compass Predicts the Service Life of Structures in Marine and Seawater Services


Service Life Prediction for Carbon Steel Storage Tank with Stainless Steel 304 Clad Bottom

In a major expansion program, a plant installed several hundred large storage tanks. Most of the older tanks were made of ordinary carbon steel and completely coated on the inside with a baked phenolic paint. The solutions in the tanks were only mildly corrosive to steel but contamination of the product was a major consideration. The coating on the floor was damaged because of mechanical abuse and some maintenance was required. The tops and sides were made of steel, with the sides welded to the stainless steel (304) clad bottoms. The steel was coated with the same phenolic paint, with the coating covering only a small portion of the stainless steel below the weld. A few months after start-up of the new plant, the tanks started failing because of perforation of the side walls. It was observed that most of the holes were located within a 2-inch band above the weld.
This is a classic galvanic corrosion case involving the question of which metal to coat – carbon steel or stainless steel. In GC-Compass (Figure 9), we use tap water to represent the mildly corrosive solutions in the tank. The uncoated stainless steel tank bottom and the coating breaks/defects/holidays on the coated carbon steel ensues a cathode to anode area ratio of at least 300. GC-Compass predicts that galvanic corrosion would perforate the wall thickness in 0.225 years (2.7 months)! Other galvanic corrosion prediction software based on the static "curve crossing" methodology simply fail to model this critical effect of cathode to anode area ratio on the galvanic corrosion rate and galvanic compatibility.


Figure 9 GC-Compass Predicts Galvanic Corrosion and the Effect of Cathode-to-Anode Area Ratio in Carbon Steel Storage Tank with SS304 Clad Bottom


Service Life Prediction of a Aluminum Casing of a Water Heater

A hospital needed an emergency power supply in case of mains failure, so a diesel engine was provided. To ensure that the diesel would cut in immediately if the power failed, it was kept warm by means of a water heater with an aluminum casing. After a few months in operation, the 8 mm thick aluminium casing was penetrated causing the water to leak out. Inspection showed that a copper heating element had been used. Copper ions deposited at the 12 o'clock position by convection and caused extremely rapid pitting.
In GC-Compass (Figure 10), the Al-Cu galvanic couple is selected and it predicted that the 8 mm thick Al casing would be perforated in 0.292 years (3.5 months).  Other galvanic corrosion prediction software based on the static "curve crossing" methodology simply fail to model this critical effects of service temperature and cathode to anode area ratio on the galvanic corrosion rate and galvanic compatibility in tap water.


Figure 10 GC-Compass Predicts Pitting Corrosion Due to Galvanic Effect in Aluminium Casing


The powerful applications of GC-Compass are truly unlimited in engineering design, galvanic corrosion prediction and modeling, materials compatibility assessment, trouble-shooting process-related issues and failure analysis of components and systems. Figure 11 shows the feature comparison between GC-Compass and other software based on curve-crossing methodology.

Figure 11 GC-Compass Offers More Features Than Other Software Based on Curve-Crossing Methodology.


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