Do I need to worry about dissimilar metal corrosion if I choose a grooved ductile iron coupling? we will explain how dissimilar metal corrosion occurs and why choosing a grooved mechanical pipe joining solution is ideal for joining stainless steel and copper piping systems.
Strength, corrosion resistance, and low cost of maintenance are all reasons that mechanical building services projects may call for the use of stainless steel pipe. But how should stainless steel pipe be joined together? And
In dissimilar metal corrosion, the most severe attacks occur between metals that have greater differences in relative potentials. For example, titanium and aluminum would have a far greater or severe attack, in a dissimilar metal situation, than copper and brass would. This is due to the fact that titanium and aluminum have a greater difference in relative potentials when compare to copper and brass.
What Is An Electrolyte As It Relates To Metal Corrosion?
To understand how and why the “attacks” occur between dissimilar metals, we will look at the flow of ions from one metal to another.
All metals have specific relative electrical potentials. When metals of different electrical potentials are in contact in the presence of an electrolyte, a low energy electrical current flows from the anodic metal to the cathodic metal. As previously mentioned, more noble metals are cathodic; metals that are less noble are anodic and are more likely to corrode relative to the cathodic metal that it is in contact with.
Can I use grooved ductile iron coupling on steel pipe?
Yes, you can use stainless steel couplings on stainless steel pipe; however, it can be costly and may not be necessary on some applications. Some projects will specify stainless steel piping because of the external environment surrounding the piping system. While the fluid media is isolated from contact with the coupling housings by the gasket, the pipe joint must be protected from exterior water.
Situations where exterior moisture can build-up and where the dissimilar metals are in contact include:
- pipe sweating
- buried applications
- submerged applications
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Post time: Apr-26-2021