Abstract: Objective Pressure testing is universally mandated in national safety regulations for pressure vessels, with corresponding standards and specifications ensuring compliance. Natural gas storage tanks manufactured by welding processes feature reinforced central girth welds. Recent frequent safety incidents have caused severe economic losses. Studying failure modes during burst tests provides critical guidance for fire rescue and emergency response. Methods Based on the acoustoelastic principle, ultrasonic methods enable nondestructive stress measurement. This study develops a dynamic stress monitoring approach using ultrasonics, designing a prototype multi-channel stress monitoring system. Through channel-cycling switching technology and magnetic fixtures securing probes to both sides of the tank’s girth weld, continuous nondestructive monitoring of multi-point stress variations was achieved. On a large-scale hydrostatic test platform, tracking residual stress evolution during progressive pressurization of liquefied natural gas (LNG) storage tanks was performed, fulfilling burst simulation requirements. Field stress monitoring experiments were conducted. Results Thin-walled welded natural gas tanks exhibited non-uniform gourd-shaped deformation under internal pressure. The reinforced central girth weld imposed stronger restraint, limiting deformation at the tank’s waist region. Due to stress concentration, asymmetric comprehensive stresses developed across the weld. Conclusions The ultrasonic method provides a new nondestructive measurement technique for the hydrostatic burst testing of pressure vessels, as well as for the monitoring and tracking of high-stress areas in pipelines and equipment. This research provides methodology and technical support for pressure vessel design under extreme strain conditions.