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SPOTLIGHT


the tested panels (over 135 in number) it was recommended by the coating consultants that a single coat application of a hot applied solvent free epoxy would be the preferred system for the long life protection, which in the 1970s was estimated to be 25 years before first maintenance. This was an exceptional projection at that time, considering coating life on similar structures was estimated to be up to 12 years. The Thames Barrier had to last double the expected time with this coating system. There were three coating


Clockwise from top left: The external testing was carried out using rope access; 1977 selected test panel from sigma coatings (PPG); Close-up of jetting head showing spinning nozzles and seal; The paint condition after local cleaning and prior to test; Repainted surface with weld stripe coats; The vacuum high pressure water jetting unit in operation on the upturned gate; A view of the cleaned 25 year old coating; Safety enclosure for the water jetting unit; The water jetting unit.


suppliers who had put forward the hot applied, high build single pack, solvent free systems. All three of these performed well, but when the detailed coating specification had been prepared and the contract submissions assessed, the blasting and coating application went to Jack Tighe Ltd and the coating selected from the short list was supplied by Sigma Coatings (now PPG). The coating works were carried out at Cleveland Bridge in Teesside and the surface preparation and application was by Jack Tighe Ltd. The work was carried out to an extremely high standard for the time, so as to achieve the optimum life to first major maintenance, projected to be 25 years.


TIGHT CONTROLS All of the work in the preparation of the steel and application of the coatings was meticulously carried out by skilled and experienced operatives with tight quality control checks at all stages. These high quality pioneering standards were taken on board by the Institute of Corrosion, and formed the initial basis of the Institute of Corrosion Coating Inspector qualification scheme, subsequently adopted by NACE International. This was also followed more recently (since 2004) by the introduction of the Institute of Corrosion’s ICATS scheme, which trains and qualifies surface preparation and


18 PCE APRIL-JUNE 2013


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