| 摘要 |
PROBLEM TO BE SOLVED: To improve a design freedom while assuring flow passage closing performance at the time of usage of a maintenance seat in a spherical valve where a valve body is made to be in secondary eccentric state.SOLUTION: A contact position between a maintenance seat 7 and a valve body seat 10 on the upstream side of a valve body 5 is set to a peripheral edge position of a bottom surface of a circular cone Cm with a center point in a flow passage 1 of a rotary center axis p of the valve body 5 as a top point, so as to enable the flow passage 1 to be securely closed when the maintenance seat 7 is used; and a center axis Qm of the circular cone Cm is inclined with respect to a center axis X of the flow passage 1 to cause the center Om of the circular contact part to be positioned on the center axis X of the flow passage 1, so as to make the outer peripheral surface of a cylinder part 8a of a maintenance seat holding member 8 fitted into an upstream side opening of a valve case 2 concentric with the flow passage 1, and suppress the occurrence of interference between a maintenance seat holding member 8 and a piping bolt screwed into the upstream end surface of the valve case 2 over an entire circumference of the valve, and thereby improving freedom in design. |
