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Dielectric Union Galvanic Corrosion Risk Evaluator

Check the galvanic corrosion risk between two dissimilar pipe metals and whether a dielectric union is recommended.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Galvanic corrosion risk level

3 Risk Level (1=Low, 2=Medium, 3=High)

Check your inputs

This is general reference guidance based on typical galvanic series relationships for common plumbing metals — always use a dielectric union or approved isolating fitting whenever joining dissimilar metals in a wet system, regardless of the indicated risk level, per code requirements in most jurisdictions.

At the values currently entered, the galvanic corrosion risk level works out to 3 Risk Level (1=Low, 2=Medium, 3=High). Confidence is moderate: the method is sound, but real materials and site conditions vary. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

Add the equipment this sizes

This result is a specification — 3 Risk Level (1=Low, 2=Medium, 3=High) — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Galvanic corrosion risk depends on the two metals' positions in the galvanic series — dissimilar metals far apart in the series (e.g. copper and steel/aluminum) corrode faster when in direct contact with an electrolyte present, and a dielectric union or fitting is commonly used to electrically isolate them. Common plumbing metal-pair risk levels below are general reference guidance, not a substitute for a corrosion engineer's assessment on critical systems.

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Frequently asked questions

Why do copper and steel have a high galvanic corrosion risk together?
Copper and steel sit far apart in the galvanic series, so when joined directly in a wet system they form a strong galvanic cell — the steel (the more anodic metal) corrodes preferentially and much faster than it would on its own.
Why is brass paired with copper low risk?
Brass and copper are close together in the galvanic series, so the electrochemical potential difference between them is small, resulting in minimal accelerated corrosion when they're joined directly.
Does a low risk score mean I don't need a dielectric union?
No — this is general reference guidance only, not a substitute for a corrosion engineer's assessment on critical systems. Most plumbing codes require a dielectric union or approved isolating fitting whenever dissimilar metals are joined in a wet system, regardless of the indicated risk level.