Corrosion protection for hydraulic steel structures - a survey of actual problems and an outlook to the future

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Corrosion protection for hydraulic steel structures - a survey of actual problems and an outlook to the future

Binder, G.

Environment protection and occupational safety is of main interest for corrosion maintenance and service operations in general and particularly in case of old coating removal. Blasting of coatings containing old coal tar sets free polycyclic hydrocarbons (PAH) which are carcinogenic as well as asbestos fibres used as filling material. Present publications on corrosion therefore demand for new techniques of coating removal where a minimum of PAHs and fibres are emitted. The development of corrosion protection materials during the last decade is characterised by the reduction of environmentally incompatible and toxic agents. Coatings became free of carcinogenic coal tar and subsequently they were reduced in solvents. The results of numerous tests, in laboratory as well as in practice, have shown that the protection quality in general didn't suffer by that. As a consequence of the solvent reduction the thickness of single polymer layers could be raised up to 1000 micron. New test results of outdoor exposure tests as well as laboratory short tests confirm the decisive influence of the make-up of a corrosion protection system. Systems with primers, especially zinc-dust primers, reduce rusting of substrate as well as blistering at the artificial scribe. Also the resistivity to electric current, e.g. by cathodic corrosion protection, is meliorated by zinc dust primers. Nevertheless, some systems without (zinc-filled) primer show also good performance.