Type Galvalum III DCW

The Type Galvalum III DCW Aluminum Alloy is an Al/In/Zn was designed as an effective, offshore alloy, for use in cold, deep water environments. This alloy is specially suited for use in cold water or marine silt at temperatures < 7° Celsius (45° Fahrenheit). The alloy has a controlled chemistry, which maintains the key elements of the alloy in tighter ranges to guard against a possible non-activation of the anode at lower temperatures. However, this alloy is also suitable for ambient temperature seawater. Chemical composition and electrochemical performance data are provided below:

Chemical Composition (% by weight)

Iron (Fe) 0.06 max
Silicon (Si) 0.08 - 0.12
Copper (Cu) 0.003 max
Zinc (Zn) 4.75 - 5.25
Indium (In) 0.016 - 0.025
Cadmium (Cd) 0.002 max
Others (each) 0.02 max
Aluminum (Al) remainder


Open Circuit Potential (-) 1.15 V vs Cu/CuS04 sw.
Closed Circuit Potential (1) (-) 1.05 V vs Ag/AgCl sw,
Seawater Capacity @25C 1150 A-Hr/lb. (2530 A-Hr/Kg.)
Seawater Capacity @5C 1150 A-Hr/lb (2530 A-hr/Kg.)
Seabed Mud Capacity (3) 950 A-Hr/lb. (2090 A-hr/Kg.)
Seabed Mud Capacity @ 5C 950 A-Hr/lb. (2090 A-hr/Kg.)


Alloy Density 0.098 lb/in3 (2.71 gm/cm3)
Cost Ratio Low Iron (Fe) Aluminum (Ai) Ingot <0.05
Raw Material & Convesion 1.10

Recommended Applications

Offshore Structures (Platforms, Pipelines, FPS, FPSO, MODU, SPAR, Subsea Structure, Risers, Wind Turbine, etc) Any Ocean. Any Depth. Any Temperature.
Inshore Structures (Ports, Harbors, Jetties, Wind farms, Locks, Dams, Bridges, Piers, etc.) Any Body of Water, Any Depth, Any Temperature with Chloride Ion Concentration > 12 ppt. Resistivity < 200 ohm-cm.
Produced Water Vessels & Tanks Any produced brine < 140 F(60 C)(4). No improvement over houstonALUM III DCW alloy.
Seawater Ballast Tanks Suitable for most seawater applications (5). No improvement over Type Galvalum III DCW.


1 - Recommended number to use when designing CP systems.
2 - Activation can be a problem with chemistries at extremes of specification in cold water.
3 - Recommended number to use when designing CP systems for offshore pipelines using bracelet or sub bottom anode systems.
4 - Consult a CP Specialist for guidance at elevated temperatures as performance de-rating will be needed.
5 - Exercise care with variable ballast tanks as dangerous volumes of hydrogen can be generated under certain conditions.
For additional guidance in application of these alloys, contact Houston.

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