PCS PCS Coating Systems and Specifications 2 — Questions and Answers
Question 1: A coating specification requires a 'holiday-free' lining. Which test method is used to detect pinholes and voids in an immersion-service lining?
- Pull-off adhesion test
- High-voltage spark testing (Correct answer)
- Cross-cut tape test
- Salt spray test
Correct answer: High-voltage spark testing
High-voltage spark (holiday) testing uses an electrical current to locate discontinuities in immersion-service linings where pinholes would allow corrosive media to reach the substrate.
Question 2: Which resin type is generally preferred when a coating specification calls for chemical resistance to hydrocarbon solvents?
- Alkyd
- Vinyl
- Epoxy (Correct answer)
- Latex acrylic
Correct answer: Epoxy
Epoxy coatings offer superior chemical and solvent resistance due to their highly cross-linked structure, making them the preferred choice for hydrocarbon environments.
Question 3: What does 'pot life' mean in a coating specification for a two-component product?
- Shelf life before opening
- Time the mixed coating remains usable after mixing (Correct answer)
- Drying time to recoat
- Total project working hours
Correct answer: Time the mixed coating remains usable after mixing
Pot life is the period during which a mixed two-component coating maintains its workable viscosity and can be applied before cross-linking renders it unusable.
Question 4: When a specification states 'theoretical spreading rate of 320 sq ft/gal at 5 mils DFT,' what adjustment must a contractor make in practice?
- Double the rate for safety margin
- Apply a loss factor for overspray, runs, and waste (Correct answer)
- Use the theoretical rate as-is
- Reduce DFT to 3 mils to improve coverage
Correct answer: Apply a loss factor for overspray, runs, and waste
Theoretical spreading rates must be adjusted by a realistic application efficiency or loss factor (typically 20–30%) to account for overspray, material waste, and surface irregularities.
Question 5: Which standard provides minimum requirements for protective coating specifications on steel structures?
- ASTM D4138
- SSPC-PA 1
- NACE SP0169
- SSPC-CS 23.00 (Correct answer)
Correct answer: SSPC-CS 23.00
SSPC-CS 23.00 provides minimum requirements for the content and format of protective coating specifications for steel structures.
Question 6: A coating specification calls for a minimum 'overlap' on stripe coats. What is the purpose of a stripe coat?
- To provide a decorative band of color
- To ensure edges, welds, and corners receive adequate film build (Correct answer)
- To test for adhesion at selected spots
- To identify different coating zones
Correct answer: To ensure edges, welds, and corners receive adequate film build
Stripe coats are applied by brush or roller specifically to edges, welds, bolts, and corners where spray application produces insufficient film build due to surface geometry.
PCS PCS Coating Systems and Specifications 2
A coating specification requires a 'holiday-free' lining.
Which test method is used to detect pinholes and voids in an immersion-service lining?