Coating Failure Analysis Calculator

This calculator turns standard coating inspection data — ASTM D4541 pull-off adhesion, ASTM D3359 Method B cross-cut rating (the 5B-to-0B tape-test scale used industry-wide for field adhesion checks), dry film thickness measurements, and service environment — into a single 0-100 failure risk score plus a list of likely failure modes, rather than leaving you to interpret each test in isolation. Adhesion is judged against an environment-specific minimum (200 PSI for indoor mild service up to 600 PSI for immersion/chemical exposure); failing that minimum adds 35 risk points outright, while passing but with less than a 20% or 50% margin still adds smaller penalties, since marginal adhesion is a leading indicator of future delamination even before a coating technically fails. Cross-cut rating contributes risk proportionally (5 points per rating step from 5B down to 0B), and thickness is checked two ways: overcoating beyond 1.5× the specified DFT adds risk for solvent entrapment and mud-cracking potential, while undercoating below 80% of spec adds a larger penalty since insufficient film build is the more common root cause of premature corrosion.

A thickness variation above 40% between min and max readings flags uneven application. Environment severity itself adds a baseline risk contribution, and the calculator also estimates remaining service life by comparing years in service against an environment-specific expected lifespan (from 20 years indoor mild down to 5 years in immersion/chemical service), adding risk once more than 80% of that expected life has been consumed. The resulting score and failure-mode list are diagnostic guidance based on industry rules of thumb, not a certified engineering assessment — a genuine failure investigation should still involve cross-sectioning, adhesion retesting at multiple locations, and comparison against the original coating specification.