203 配管突合せ溶接部の残留応力改善手法の開発(関東支部茨城講演会)

概要

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To reduce tensile residual stress and to prevent occurrence of the Stress Corrosion Cracking at a butt-welding piping, a new stress improvement method-which freezes water and expands piping diameter in a welded region-was developed. In this method, piping is cooled and ice stoppers are made the inside at both sides of a welded region. The area between ice stoppers is watertight, so we can expand piping diameter by cooling and freezing water in a welded region. When piping diameter is expanded, the hoop strain that occurs the inner surface is larger than that of the outer one. So the plastic deformation remains and occurs compressive residual stress at the inside surface. The effect of expansion of piping diameter was evaluated by the FEM analysis then verified by experimental measurements. As a result of testing, we confirmed that hoop and axial residual stresses in a welded region of the inner surface were changed into compressive residual stress by expanding the piping diameter.
社団法人日本機械学会の論文
2005-09-08