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The nylon AquaTechnic pipe bushings are designed specifically to insulate connections in liquid and gas systems between piping of different metals, such as iron or galvanized connected to copper or high copper content brass.
Even little mineral content water performs as electrolyte would in a battery. No current will be produced if two pieces of the same metals were immersed in an electrolyte and connected, but if two different metals are used, a current will flow in a circuit through the electrolyte and any metallic connection outside the electrolyte (water). The dielectric bushing interrupts the metallic circuit and the electrical current. If the electric circuit is completed, as in metal-to-metal contact with the different pipes, the current through the water-electrolyte produces ions at the water-to-metal interference that is destructive of one or both metals. In the connection of copper to iron or galvanized, destruction or corrosion of the iron occurs with a substantial buildup of rust (iron oxide) inside the pipe. The pipe wall may become corroded entirely through, and the inside passage will become severely restricted. If the outside of the copper-iron pipe connection becomes wet due to condensation, or if the joint is immersed in water, corrosion of the iron will also occur on the outside.
The mineral content and acidity of the water supply affects the rate of corrosion, and both the mineral and the acidity vary in water supplies. Hot water is much more active than cold water, and many times a hot water pipe may choke to a trickle of water, yet the cold pipe next to it may be only moderately corroded. The corrosion typically occurs in pipes within only 3 or 4 inches of the joint in pipes of 3/4 sizes or smaller. If copper tubing is connected directly to a galvanized hot water tank, the entire inside of the tank is likely to corrode, with the zinc proceeding into the iron. Many such progressions have been observed. Any pinholes or bare spots in glass-lined tanks will corrode rapidly if the copper tubing is connected directly to the tank.
Since the current developed in this corrosion process has the potential of only about 1-1/4 volts, any insulating interruption of the circuit will stop the corrosion. Nylon is a tough material and in the formulation used in AquaTechnic Bushings are resistant to water and the minerals formed in boat water supplies up to 180F and higher. AquaTechnic’s bushings are provided in two (2) different materials depending on the pressure and temperature requirements.