© 2022 Elsevier LtdThis paper focuses on investigation of effects of defects, which may occur during manufacturing process, on bursting behavior of filament wound composite pressure vessels. A comprehensive experimental study was carried out to understand how manufacturing defects affect bursting behavior of pressure vessels with various stress ratios. Firstly, effect of stress ratio on bursting behavior was studied with the pressure vessels with no defect. Safe and unsafe failure modes were determined for pressure vessels with different stress ratios. Then, delamination and gap defects were deliberately embedded to pressure vessels with safe and unsafe failure modes. Thus, effects of manufacturing defects on bursting behavior for pressure vessels with both safe and unsafe failure modes were studied successfully. Strain gage measurement and high-speed camera were utilized to interpret bursting behavior in detail.