Research on reduction of residual stress in girth welds of large-diameter natural gas pipes by ultrasonic

ABSTRACT Excessive residual stress of the girth weld in pipes will directly damage pipe strength during its operation. Accurate measurement and effective reduction can ensure safety natural gas their service. In this paper, an X80-type large-diameter section with welds is taken as research object. The coercive force method used to characterize surroundings, then distribution law surroundings obtained based on results Blind-hole method; ultrasonic impact was reduce stress, effect studied by comparing changes characteristics before after pipes. Lastly, in-situ test specimen made carry out uniaxial tensile so study mechanical properties welds. This clarifies influence toe materials, provided technical theoretical guidance for field