Study on Insulation Length for Galvanic Corrosion in Water Piping Systems in Buildings

Abstract

The insulation between the different kind metals is done as a prevention measures of the galvanic corrosion that occurs in the equipment piping system. However, it has not been clarified still enough up to now for the insulation length when an external circuit is formed. A carbon steel pipe as the anode and a stainless steel pipe as the cathode were combined. A basic experiment that measured the corrosion potential distribution and the galvanic current distribution in the tap water environment was done. As a result, the following etc. were clarified. 1) The corrosion of the carbon steel pipe with the boundary part of the cathode and the anode is large, and the influence in the boundary part as the cathode of a stainless steel pipe is large. 2) When the diameter of piping grows, the extent is eased when the diameter of piping is small though corrosion concentrates on the edge of the carbon steel pipe. 3) A galvanic current decreases exponentially according to increase in the insulation pipe length.