Material Selection Flashcards

Thermal spray aluminum (TSA) is often preferred over thermal spray zinc in which environment?

Answer: Marine and elevated-temperature service such as CUI

TSA performs well in seawater and elevated temperatures where zinc may consume rapidly or reverse polarity.

Why is coal tar epoxy use declining in many U.S. projects despite good immersion performance?

Answer: Health and environmental concerns over polycyclic aromatic hydrocarbons

Coal tar contains PAH carcinogens, prompting regulatory restrictions and owner preference for alternatives.

When choosing a topcoat for an existing aged alkyd system, which is the main risk of using a strong-solvent two-component epoxy?

Answer: Lifting or wrinkling of the old alkyd from aggressive solvents

Strong solvents can soften and lift oxidatively cured alkyds, so compatibility testing is essential.

Which factor is most critical when selecting coatings for low-temperature application in winter?

Answer: The minimum cure temperature specified by the manufacturer

Each coating has a minimum substrate and air temperature below which it will not cure properly, so low-temp versions may be required.

In a galvanic couple, why should a small anodic area coupled to a large cathodic area be avoided in material selection?

Answer: It concentrates corrosion on the small anode, accelerating attack

An unfavorable area ratio focuses galvanic current on the small anode, causing rapid localized corrosion.

Which coating type is commonly selected for lining hot water or crude oil storage tanks requiring resistance to elevated-temperature immersion?

Answer: Epoxy phenolic

Epoxy phenolics offer excellent chemical and temperature resistance for immersion linings.

Fluoropolymer (FEVE) topcoats are typically justified on which basis?

Answer: Exceptional long-term weatherability lowering life-cycle cost

FEVE fluoropolymers have very high UV resistance, offering decades of color and gloss retention that offsets higher upfront cost.