Probabilistic reliability assessment of butt-welded joints under pressure using FAD and the FORM

This study aims to assess the reliability of butt-welded joints under increasing pressures (20, 40, and 60 bar) using FAD and the probabilistic FORM. The material used in the study is A48 AP steel. The analysis focuses on three specific areas of the welded joint: base metal (BM), weld metal (WM), and the heat-affected zone (HAZ). The results show a significant decline in reliability as pressure increases, with the weld metal becoming particularly vulnerable starting at 40 bar. At 60 bar, the base metal exhibits the lowest reliability index (4.99), indicating a heightened risk of failure. While the probability of failure remains low at 20 bar, it increases substantially as pressure rises, particularly affecting the weld metal and base metal. As a result, it is recommended to implement continuous monitoring programs and preventive maintenance once the safety factor drops below 3.0, ensuring the long-term integrity of welded structures.