Galvanic corrosion - Principles and practice for use of titanium

Titanium is normally the cathode in mixed metal structures. Guidelines for design and application based on the principles of avoidance or minimising galvanic corrosion do not necessarily address all of the conditions likely to be met in service. The offshore oil and gas industry in particular has provided a wide range of differing environments in which metal couples have to perform, frequently with different media on either side of the coupled component. Metals galvanically close to titanium may perform satisfactorily with titanium in one environment, but suffer corrosion in another. Titanium may also be coupled to materials more noble than itself. The increasing use of composites adds a new dimension to the concept and practice of galvanic coupling. The data base of field experience continues to grow and qualifications continue to be added to the basic guidelines in the light of practical findings. Recommendations for installation, inspection and maintenance of mixed metal systems often prove inadequate to prevent trouble over longer periods of service.