Down-pipe support material must not promote:

Down-pipe support material must not promote:

• A. Corrosion
• B. Galvanic action
• C. Pitting
• D. Erosion

Answer: (B)

When different metals are in contact in the presence of moisture, an electrochemical cell can form and drive galvanic action. That means one metal (the anode) corrodes faster while the other (the cathode) is protected. Down-pipe supports in HVAC are often in damp environments, so using dissimilar metals together or allowing metal-to-metal contact without insulation creates a pathway for galvanic corrosion. The safest approach is to use compatible metals, or isolate the metals with non-conductive spacers or coatings, or use the same metal throughout. This prevents the accelerated, targeted corrosion that galvanic action causes.

When different metals are in contact in the presence of moisture, an electrochemical cell can form and drive galvanic action. That means one metal (the anode) corrodes faster while the other (the cathode) is protected. Down-pipe supports in HVAC are often in damp environments, so using dissimilar metals together or allowing metal-to-metal contact without insulation creates a pathway for galvanic corrosion. The safest approach is to use compatible metals, or isolate the metals with non-conductive spacers or coatings, or use the same metal throughout. This prevents the accelerated, targeted corrosion that galvanic action causes.