WELDING STRUCTURE OF STUB TUBE

PROBLEM TO BE SOLVED: To prolong the creep life of a stub tube welding part to be the weakest point portion in a header and a stub tube, by reducing stress generated in the stub tube welding part.SOLUTION: In a welding structure of a stub tube, when the outer diameter of a header is defined as D, the wall thickness of the header is defined as T, and the outer diameter of the stub tube is defined as d, the wall thickness t of the stub tube is within a range indicated by the following relationship: (1.1d/2)/([2/{(Ro/Ri)-1}]+0.5)≤t≤(0.9d/2)/([1/{(Ro/Ri)-1}]+0.5), where Ro: the external radius of the header (Ro=D/2), and Ri: the internal radius of the header (Ri=Ro-T). 【課題】スタブ管溶接部に発生する応力を低減させて、母管及びスタブ管における最も弱点部位であるスタブ管溶接部のクリープ寿命の長寿命化を実現すること。【解決手段】スタブ管の溶接構造において、母管の外径をＤ、母管の肉厚をＴ、スタブ管の外径をｄとした場合、スタブ管の肉厚ｔが次式に示す範囲内にあることスタブ管溶接構造。（１．１ｄ／２）／（［２／｛（Ｒｏ／Ｒｉ）２−１｝］＋０．５） ｔ （０．９ｄ／２）／（［１／｛（Ｒｏ／Ｒｉ）２−１｝］＋０．５）Ｒｏ：母管の外半径（Ｒｏ＝Ｄ／２）、Ｒｉ：母管の内半径（Ｒｉ＝Ｒｏ−Ｔ）【選択図】図１