Development of 4-way Pipe Stress Reduction Machine for Improved Submerged Arc Welding Pipe Dimensional Accuracy and Reduced Residual Stress

This paper deals with development of a 4-way press stress reduction machine to improve dimension accuracy of submerged arc welding pipes. FEA simulation was used to verify therotetical machine capacity because pushing distance and pressing force are main factors deciding machine capacity. The 4-way pipe stress reduction machine has four tools surrounding the pipe and pressed against the pipe by a hydraulic press. Pushing results in improved pipe roundness and less residual stress can be achieved because of the Bauschinger effect. If the pipe has less residual stress, cut sections rarely suffer distortion and high dimensional accuracy can be obtained without any pipe loss. In addition to dimensional accuracy, this machine does not require any washing equipment such that both installation space and cost can be reduced. Dimensional accuracy and residual stress were evaluated by FEA simulation and these results were compared to prototyping parts.