Residual stresses are thermal stresses that arise in materials during manufacturing processes like uneven cooling, flame cutting, and welding. The manufacturing technique used for steel sections affects the levels and patterns of residual stress, which consequently impacts the strength against Lateral Torsional Buckling (LTB). This research investigates how residual stress influences the calculation of LTB strength in web tapered welded I-beams. Specifically, a simply supported and unrestrained beam with a length of 3700 mm is examined under destabilized loading conditions with varying taper ratios. The study also considers standard residual stress patterns obtained from existing literature, highlighting that LTB failure tends to occur at lower moments for web tapered welded I-beams. By comparing and discussing the results of Load-Lateral displacement and Load-vertical displacement for different taper ratios, this study provides valuable insights. Ultimately, these findings contribute to the future advancement of numerical simulations for asymmetrically tapered welded I-beams.