Cathodic Protection: A Comparison of Results of Long- and Short-Term Testing of Aluminium Sacrificial Anodes
Abstract
Cathodic protection is one of the most important air-corrosion systems used by the Royal Australian Navy (RAN) to reduce the ravages of sea water corrosion of the hulls of their ships. For the galvanic (sacrificial) system, the RAN has standardized on the use of hull anodes based on aluminium. Most of these aluminum anode alloys are based on a ternary composition of the type Al-Activator-Zinc 2,3,4, where the activator is usually mercury, indium, gallium or tin and is used in low concentrations (e.g. 0.02-05%). For the RAN, it is desirable that satisfactory locally-produced commercial anodes be available with similar formulation to overseas anodes. These are made using local raw materials and, therefore, may contain different impurity levels from those produced overseas. It is necessary, therefore, that an evaluation be made of commercially produced anodes that may be used for the cathodic protection of Australian Naval vessels. This evaluation can be done either using short-term accelerated testing procedures or by long-term (i.e. 12 months or more) field trials. One such short-term test that has been used 6,7 to assess the performance of aluminium galvanic anodes is based on the Australian standard specification AS 2239-1979, Appendix C. The purpose of this paper is to give some indication of the reliability of the short-term test in As 2239 to predict the long-term efficiency of aluminium alloy galvanic anodes for use in cathodic protection systems in sea water.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1988
- Accession Number
- ADA205405
Entities
People
- B. S. Smith
- B. T. Moore
- J. J. Batten
Organizations
- Defence Science and Technology Group