Corrosion protection for seawater filters

Galvanic corrosion protection is commonly applied to low-budget filter systems, where the zinc coating from hot-dip galvanising serves as a sacrificial anode. This has the disadvantage of a limited life; the zinc will locally dissolve within a few years. The use of corrosion-resistant alloys is a highly satisfactory, though expensive, solution, which because of the cost is normally used for the filter element only.

Armaturen-Wolff says that it can offer another solution, namely an FBE (fusion-bonded epoxy) powder coating. The filter is sand-blasted and washed before being sprayed with epoxy powder at a controlled temperature, to a film thickness of 250-500μm. The smooth sealed surface prevents encrustation by salts and organic substance, and remains effective as long as the layer remains intact.

For an even longer lifetime, Armaturen-Wolff offers a 4.0mm thick hard rubber lining, which is directly vulcanised onto the filter. The company claims that the lifetime can equal the economical life of the vessel itself, and because of the long life and low maintenance requirement the cost can prove highly competitive. The rubber lining is bonded to the filter after all edges and weld seams have been rounded off, with no cavities or large pores. After sandblasting and application of a bonding agent, the lining material is cut to size and fitted into the filter, before the entire filter is put into an autoclave for curing.