PROBLEM TO BE SOLVED: To provide a flange joint which enables improvement of strength of a welding part between a pipe member and the flange joint and can prevent occurrence of welding strain on a flange surface after welding, and to provide a piping material.;SOLUTION: A flange joint 11A has: first and second flange surfaces 12, 13 arranged back to back; a large diameter hole 16 opening on the first flange surface 12; and a small diameter hole 17 opening on the second flange surface 13 and communicating with the large diameter hole 16. A taper small diameter hole chamfer part 19 which spreads to the first flange surface side is formed at a first flange surface side end part of the small diameter hole 17. A pipe member 20 is inserted into the large diameter hole 16, a flange joint side end part of the pipe member 20 contacts with a first flange surface side end part of the small diameter hole chamfer part 19, and the small diameter hole chamfer part 19 and the flange joint side end part of the pipe member 20 are welded.;SELECTED DRAWING: Figure 1;COPYRIGHT: (C)2019,JPO&INPIT
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