| 摘要 |
<p>PROBLEM TO BE SOLVED: To lower a manufacturing cost and to increase a holding strength and to prevent a lining material from peeling off. SOLUTION: A circular recess part 27 is formed in a piping connection end face 22a of a flange 22. A first annular groove 29 is formed on the bottom face 27a of the recess part 27. A second annular groove 29 is formed on the inside wall face 27b of the recess part 27 separately from the piping connection end face 22a, and the recess part 27 and the first and second annular grooves 28, 29 are covered with a lining material 4.</p> |
