Research was conducted for protecting mainly inside of steel pipe joint, using cylinder type aluminum alloy anode, which provides protective current only from the extreme end surface of the anode. A steel pipeline (300φ×30m-loop) was used for the test, and artificial sea water was continuously circulated at a velocity of 1.8m/sec. The inside of the pipeline was coated with tar-epoxy resin and others, except the neighbouring part of the welded joint. One year test showed that the pipe potential was extended to considerably wide range from the anode. The anode current was less than the initially designed value, and the anode life was expected to be fairly long.
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