Development of aluminium anodes for cathodic protection

Abstract

Comprehensive research and development work at the National Metallurgical Laboratory, Jamshedpur, India has resulted in the development of aluminium based sacrificial anodes for cathodic protection of ship hull, harbour installations, off-shore drilling and processing platform, underground pipelines and heat exchanger4 components. SUPERAL a medium output and HOPAL a high output aluminium alloy based anodes have been developed keeping in view of specific uses. For the cathodic protection of ship hull, harbour installation and underground pipelines, the former can be considered whereas HOPAL is a tailor made anode for the protection of off-shore drilling and processing platform where high efficiency and long life are desired. The anodes developed, especially by Hopal have been able to substitute the imported anodes used to protect oil platforms at Bombay High. The HOPAL anode has an electrode potential of -1.2V SCE in 3% NaCl solution and anode life of 3.0 kg per amp, year with an efficiency of 96% at ambient temperature. Various electrochemical properties of the anode material and performance at elevated temperatures have been discussed in detail in the paper. Design of HOPAL anode for a typical off-shore structure in Indian conditions has also been presented.