Photo Gallery I6:  Proper Dielectric Fitting Installation

This photo gallery illustrates the correct installation of a dielectric fitting and its purpose to eliminate the electrical conductivity between steel or galvanized steel and copper or brass.  We generally find the need for dielectrics unnecessary where corrosion activity is very low, as should exist for most closed piping systems maintaining corrosion activity at below 0.5 MPY.  Decades ago, open condenser water systems rarely had any insulation between dissimilar metals yet experienced no measurable corrosion increase.  This we have always attributed to the superior quality and inherent corrosion resistance of older pipe in combination with more effective corrosion control chemicals of that time.  Even where brass met galvanized steel, problems were rare.

Today, conditions are quite the opposite.  Direct galvanized steel to copper or brass connections are an almost certain guarantee of a galvanic induced failure.  Failures of new galvanized steel pipe threaded up to a brass valve have occurred in under 8 years.  Likewise, any open condenser water system lacking dielectrics is almost guaranteed to see their first thread failures at those areas.  The specification for dielectric fittings are a near necessity for open condenser water systems – yet are also specified for some closed piping systems as a preventative safeguard.

As the next photo gallery demonstrates, the placement of dielectric fittings to isolate dissimilar metals is still not widely understood.  In close to 30% of our UT investigations where dielectric fittings have been installed in response to a prior piping failure, they are installed wrong; providing temporary peace of mind but no benefit whatsoever.