Water Supply & DistributionQuestion 60 of 120
An existing galvanized steel water line is being extended with copper tube. What must be installed at the point where the two materials join?
a.A brass compression coupling
b.An approved dielectric fitting or dielectric union
c.A soldered joint made directly to the steel pipe
d.A rubber sleeve coupling with stainless steel clamps
Explanation
Copper and galvanized steel are far apart on the galvanic scale, so a dielectric fitting is required to break the metallic path and prevent accelerated corrosion at the joint. A brass coupling still conducts and only shifts the corrosion cell rather than stopping it. Copper cannot be soldered directly to galvanized steel, and a rubber sleeve coupling is a drainage fitting that is not rated for water distribution pressure.
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