PSI - Issue 75

Gary B. Marquis et al. / Procedia Structural Integrity 75 (2025) 530–537 Marquis, Barsoum & Leitner / Structural Integrity Procedia (2025)

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Figure 5. Maintenance and inspection procedures for life management welded steel structures [10] (left), Flowchart for the HFMI treatment of pre-fatigued structures (right). In additional to this, brief recommendations for HFMI treatment in corrosive environments is also outlined. HFMI treated structures exposed to corrosive environments may experience reduced fatigue benefits. HFMI alone does not enhance corrosion resistance, the fatigue improvement can be preserved if appropriate protective measures are applied. Coatings compliant with ISO 8501–1 surface preparation standard are recommended. 4. Verification and Standardization of HFMI Devices To ensure consistent and effective application HFMI treatment, the IIW has introduced a standardized methodology for device verification. This approach supports performance-based qualification without promoting specific commercial tools. Verification begins with fatigue testing of HFMI-treated specimens using standardized geometries and load conditions. Devices must demonstrate fatigue strength improvement aligned with IIW expectations, such as an increase in FAT classes relative to as-welded baselines (e.g., FAT 80 to FAT 125). The recommendations outlines minimum test requirements and data assessment procedures, including calculation of characteristic S-N curves and improvement factors. Verification must include one series from each of the three structural detail classes in the IIW system [9] shown in Table 2: 1) a transverse butt weld, 2) a transverse non-load carrying attachment, and 3) a longitudinal fillet welded gusset. Either the longitudinal fillet welded gusset or transverse non-load carrying attachment, figure 6, can be used to avoid secondary bending.