The general corrosion was observed on side net installed above the water level where splash of sea
water and baits adhered, but obtained value of wire gauge corrosion rate was less than the maximum
value of wire nettings installed below the water level, because the corrosion products were working protection covering on its steel wire.
Conceming the wire nettings installed below the water level, pitting corrosion was not observed on
the botton net where galvanization had just wom out, but crevice corrosion and pitting caused by formation
of oxgen concentration cell at the wire cross sections were observed near to the water level of
side net. One of the promotive factors of this corrosion is the flux of water produced by the swiming
power of culturing fish.
At the inside of the bottom net of the floating cage, galvanization on wire nettings had soon wornout owing to impacts of yellow tail Seriola quinqueradiata, but on the wire nettings to which water
jet was spouted out for the elimination of fouling organisms was not recognized deterioration of the
galvanization due to this water pressure.
On the other hand, galvanic corrosion was observed even on wire netting linked by stainless steel
rings of surface area ratio to wire netting with 1/100, in this case, wire gauge corrosion rate of the wire
nettings was 3.6 times. over than that of wire nettings linked by the identical material.
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