Case: Coating a sea water filter
A new Sea Water filter normally comes with a thin epoxy paint based coating which is not very resistant against sea water.
In addition to the exposure to sea water, the Stainless steel filter insert causes bi-metallic corrosion due to the fact that there are 2 different metals where the steel filter housing has the lowest potential and will corrode (or sacrificed) until leakages will occur.
Sea Water filter housings can be made from cast iron or cast steel where cast iron is the lowest quality.
In this case the new filter housing was made from steel plate with a stainless steel insert.
About the Job:
First the filter was prepared for shot blasting. Was shot blasted up to SA 2.5 with a good roughness (70-75 microns) to let the Wencon Coating adhere the best.
Back from the shot blasting, the housing was cleaned thoroughly with Wencon Cleaner.
Next step was to apply the Wencon 2-layer system Coating White and Blue in both 300 micron to achieve 600 micron in total. The second layer was applied when the first layer was semi-cured and still sticky.
When the coating was fully cured, the stainless steel filter insert was installed and the outside got a nice paint finish.
The filter unit is now protected for at least 10 years, if the crew is carefully when they install the insert after cleaning it to avoid impact damage to the coating.
The crew was given some Wencon Coating on board to repair eventual impact damages in the coating layer. This kind of damage inspection is important, and applies to all coating systems regardless of the coating system or brand.
With the Wencon metal free epoxy systems we avoid Bi-metallic corrosion and extend the service life of expensive and important equipment on board of a vessel.
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