Material Selection Flashcards

Galvanic corrosion is most likely when which two metals are in direct contact in a wet environment?

Answer: Copper and galvanized steel

Copper and zinc-coated steel sit far apart on the galvanic series, so the zinc corrodes quickly when an electrolyte is present.

What is the main purpose of a dielectric union in a plumbing system?

Answer: Electrically isolate dissimilar metal pipes to prevent galvanic corrosion

Dielectric unions separate dissimilar metals, such as copper and steel, to break the galvanic circuit.

Which sealant type is generally best for a moving exterior expansion joint between precast concrete panels?

Answer: Polyurethane or silicone elastomeric sealant

Elastomeric polyurethane and silicone sealants handle large joint movement and weathering far better than latex or oil-based caulks.

A facility needs ceiling tiles for an open-plan office where speech privacy is a priority. Which rating should guide the selection most?

Answer: Noise Reduction Coefficient (NRC)

NRC measures how much sound a ceiling absorbs, which cuts reverberation and improves speech privacy in open offices.

What does VOC content on a paint or adhesive Safety Data Sheet indicate?

Answer: The amount of volatile organic compounds that off-gas and affect indoor air quality

VOCs evaporate during and after application and can degrade indoor air quality, so low-VOC products are preferred in occupied buildings.

For exterior handrails in a corrosive coastal setting, which stainless steel grade is usually recommended?

Answer: Type 316

Type 316 contains molybdenum, which gives it better resistance to chloride pitting than 304.

A loading dock floor sees forklift traffic and chemical spills. Which floor coating is most suitable?

Answer: High-build epoxy or urethane cement coating

High-build epoxy and urethane cement systems resist abrasion, impact, and chemicals under heavy industrial traffic.