| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve the average compressive strength of a branch pipe and to reduce dispersion of average compressive strength by substantially equalizing the insert length of piping inserted in a pair of hollow branch parts with the same length branched from the hollow trunk part of a branch pipe and the length of the hollow branch part. SOLUTION: A large decrease in the average compressive strength of a branch pipe 4 is caused by the difference of degree of stress concentration depending on where piping 9 is inserted to the length of the hollow branch part 4e of the branch pipe 4. That is, the burst pressure of the branch pipe 4 increases in proportion to the insert amount of the piping 9. Accordingly, the insert length 9L of the piping 9 inserted in a pair of hollow branch parts 4e with the same length which branched from the hollow trunk part 4d of the branch pipe 4 is made substantially equal to the length 4eL of the hollow branch part 4e. Thus, the stress concentration can be lessened by equalizing the length 4eL of the hollow branch part 4d and the insert length 9L of the piping 9 to improve the average compressive strength. Further, dispersion of the average compressive strength can be reduced.</p> |
