Design plays a very important part in corrosion protection and it is necessary to monitor equipment in service to detect and correct defects. For many years oil filled power transformers had round or elliptical tubes welded into holes punched in header pipes or directly in the tank side. The welding was on the inside leaving a small cavity between tube and header which was a source of corrosion after around 10 to 15 years in service. Modern transformers use plate type radiators with external MIG welding which seals any gaps. These radiators are fixed to the transformer on gasketed flanges and can be replaced if necessary. Surface preparation after fabrication consists of removal of all weld slag followed by grit blasting to BS 4232 2nd quality (SA 2.5) using grit G17 to BS 2451. This is followed, within four hours, by application of primer or a metallic zinc coating applied by flame spray.
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