Internal Corrosion of steel pipes installed in a synchronous condenser cooling system resulted in rapid penetration and failure in certain locations at a large electric substation on the west shore of South San Francisco Bay a few years ago.
Visual inspection of the failed nipples lead operating personnel to believe that erosion caused the trouble. These 2.5 and 1.0-inch ID pipe nipples failed on the downstream side and adjacent to control valves regulating waters flow. Although these restricted areas have turbulent action and increased velocity which accelerate the rate of failure, they Avere not the primary reasons for failure.
Water for cooling the two synchronous condensers comes from a station well at 175 gallons per minute for each condenser. In this once-through cooling system, water temperature rise is about 7 F in passing directly through the heat exchanger before discharge into the bay. Resistivity of the water was 380 ohm-cm...
