Optimizing Inspection Intervals in Aging Offshore Facilities Using Advanced NDT Evidence within a Risk-Based Governance Framework (Published)
Aging offshore infrastructure—particularly in mature basins such as the North Sea and Gulf of Mexico—faces escalating integrity management challenges as assets operate well beyond their original design lives. While Risk-Based Inspection (RBI) has become the industry standard for prioritizing inspection efforts, a critical gap persists: conventional RBI implementations often lack a formal, auditable mechanism to leverage high-confidence data from advanced non-destructive testing (NDT) methods to dynamically optimize inspection intervals. This paper addresses that gap by proposing a structured governance framework that systematically integrates quantitative evidence from advanced NDT—such as phased array ultrasonic testing (PAUT), robotic corrosion mapping, and drone-based metrology—into the RBI reassessment process. The methodology comprises three core steps: (1) updating the Probability of Failure (PoF) by incorporating measured degradation rates and revising inspection effectiveness factors to reflect the superior Probability of Detection (POD) of advanced NDT; (2) quantifying epistemic and aleatory uncertainties through probabilistic methods such as Monte Carlo simulation to establish confidence bounds on the revised PoF; and (3) subjecting the technical findings to formal review by a cross-functional governance panel against predefined risk acceptance criteria. The framework’s efficacy is demonstrated through two real-world case studies: one involving external corrosion under insulation on a topside pressure vessel, and another addressing a fatigue crack indication in a subsea pipeline girth weld. In both cases, high-fidelity NDT data enabled defensible inspection interval adjustments—extending the interval by two years in the first case and transitioning to a targeted monitoring strategy in the second—while ensuring PoF remained within corporate and regulatory risk thresholds. The study delivers a transparent, repeatable, and regulatorily defensible methodology that empowers operators of aging assets to replace rigid, calendar-driven inspection schedules with evidence-based, risk-informed decisions, thereby enhancing safety assurance, operational efficiency, and compliance.
Keywords: Advanced Non-Destructive Testing (NDT), Aging Offshore Assets, Inspection Interval Optimization, Probability of Detection (POD), risk-based inspection (RBI)