Ensuring Asset Integrity via Non-Destructive Evaluation of Mechanical Properties in Aging Infrastructure

As assets age and operating conditions change, assessment for continuous service and life extension necessitate review of equipment integrity and fitness for service. This paper, co-authored with Occidental Petroleum and presented at ADIPEC 2025, outlines the theory and application of non-destructive mechanical testing using Automated Ball Indentation, including its mechanical model, comparison to conventional testing, and recent case studies.

One approach to fitness-for-service assessment is to utilize industry’s best practices as outlined in API RP 579/ASME FFS-1. This approach requires fracture toughness data that is not given in typical Material Test Reports (MTRs) or not available at specific operating conditions such as lower temperature Charpy Impact Energy. Since conventional destructive testing requires removal of material from critical components, it becomes impractical especially when multiple tests are needed across many piping or vessel segments from different heats.

The Haggag Fracture Toughness Method (HFTM) determines fracture toughness (KJc) non-destructively from ball indentation load-depth data by integrating indentation deformation energy up to a critical depth. The method applies two models: the critical fracture stress model (when stress threshold is reached before 12% strain) and the critical fracture strain model (when it is not). Reference Temperature (T₀) values from indentation tests at room temperature are applied to the ASTM E1921 master curve to estimate low-temperature fracture toughness.

Case Study 1 — Offshore Flare Boom: A deepwater facility flare boom required reassessment for low-temperature service during a life extension review. Replacement cost was estimated at millions of USD. ABI® testing confirmed the flare boom materials exceeded minimum fracture toughness requirements even below original MTR test temperatures, validating continued service and avoiding the replacement project entirely. Although no reference temperature tests were available from the original MTR, ABI-derived T₀ values demonstrated ample margin for continued low-temperature operation.

Case Study 2 — Production Casing in CO₂ Flood: In a West Texas CO₂ flood, production casing developed leaks at depths of approximately 4,500 feet. ABI® testing of pulled casing joints confirmed no significant degradation from the CO₂ environment compared to original MTR data, and fracture toughness was found to exceed minimum thresholds for continued service.