| 摘要 |
PURPOSE:To prevent generation of an angle in a joint part and to prevent fluid loss of a mitre bend by curving and joining plural pipe bodies of which the joint parts incline relative with the pipe axis in such a way that the diameters of the elliptical end faces in the respective joint parts are approximate to a short diameter. CONSTITUTION:A straight pipe is alternately cut at an equal angle of inclination positive and negative to the pipe axis so as to have the equal shape of the end face, thereby manufacturing plural pipe bodies 1 each having an elliptical end face 2. Each body 1 is curved in such a way that the diameter in the long diameter part of the elliptical end face 2 thereof is approximate to the diameter in the short diameter part, thus forming a curved part 3. A notch 4 to serve as a groove for inside surface welding of the bodies 1 is provided and the joint parts 2 are welded from the inside of the pipe. A weld zone 5 is so formed as to have the wall thickness equal to the wall thickness of the bodies 1. The curved parts 3 are formed at both ends in the long diameter part of the faces 2 and it is also possible to form the same only in the long diameter part of the end faces on the curving outside of the bend. |
