At first glance, the image above might seem like a standard piece of mechanical infrastructure—just another copper pipe suspended by steel hangers in a ceiling space. But if you’re involved in plumbing or HVAC installations, this seemingly ordinary setup reveals a classic mistake that can lead to long-term corrosion and costly maintenance: galvanic reaction between dissimilar metals.

What’s the Problem?

In the photo, a copper pipe is mounted directly in metallic hangers, likely made of galvanized steel based on the typical finish and industry practice. This direct contact between dissimilar metals, especially in the presence of moisture (such as condensation or ambient humidity), sets the stage for galvanic corrosion.

This is an electrochemical process where one metal (the anode) corrodes faster than it would alone, while the other (the cathode) is protected. In this pairing:

  • Steel (galvanized or not) becomes the anode — and corrodes.

  • Copper is the cathode — and remains unaffected.

  • The result? The hanger slowly deteriorates, potentially compromising the support system.

Why It Matters

While this reaction doesn’t happen overnight, it can have serious consequences in long-term installations:

  • Steel hangers weaken and may eventually fail

  • Unplanned maintenance and system downtime can occur.

  • On exposed or visible piping, it becomes a cosmetic issue as well.

For high-value systems or critical infrastructure (such as hospitals, data centres, or labs), these risks are unacceptable.

What Should’ve Been Done?

To avoid this issue, best practices and mechanical codes recommend dielectric separation between copper pipes and steel supports. This can be achieved using:

  • Rubber or neoprene isolators in the clamp.

  • Plastic-lined hangers.

  • Pipe insulation that fully separates the metal surfaces.

  • Alternatively, using copper-compatible (e.g., stainless steel) hangers.

These are small additions in the grand scheme of an installation, but they extend system lifespan and reduce risk.

How to Spot This in Your Project

If you’re a contractor, inspector, or engineer:

  • Look at pipe supports during walkthroughs—especially on copper chilled water, potable, or hydronic systems.

  • Note any direct metal-to-metal contact between copper and galvanized steel.

  • Confirm what type of hanger is specified in mechanical drawings or specs.

Final Thoughts

Galvanic corrosion is one of those “slow-burn” issues—often overlooked during construction, but eventually costing owners and facilities teams in repairs. The fix is simple, but only if it’s caught early.

Next time you look up at your piping supports, ask yourself:

“Are my hangers helping or hurting my system?”

James Hicks P.Eng.

Evolve Mechanical Solutions

236.777.3487