1) Check the sealing operation mode of the butterfly valve to confirm whether the sealing is closed by position or by torque.
2) If the sealed butterfly valve is closed with torque, under the condition of 100% medium pressure and nominal pressure difference (or rated pressure difference). The force wrench is used to detect the maximum operating torque when the butterfly valve is opened and closed. Check three times and take the maximum value.
3) Install the butterfly valve and adjust the control mode and output torque of the driving mechanism to meet the operation requirements of closing and sealing of the butterfly valve and meet the requirements of sealing performance.
4) Check the leakage of the sealing surface after 200 ~ 300 cycles of opening and closing. If the operating torque changes, the output torque of the driving mechanism should be adjusted in time to meet the sealing requirements. If the requirements of 188.8.131.52-7) are not met, the test shall be terminated.
Determination of the number of static pressure life tests:
(1) Terminate the test.
The test shall be terminated if:
① Sealing test inspection, sealing performance can not meet the standard requirements;
(2) Stem packing can not keep sealed, other parts of the valve body leakage;
(3) Butterfly valve stem, shaft sleeve and other parts wear. They can not open and close operation normally or open and close operating torque has a large change. And they does not meet the regulations.
(2) The number of static pressure life tests.
(1) After the required number of tests, when the performance of the butterfly valve meets the standard requirements. This number of tests is the number of static pressure life tests.
② During the test, if there are abnormal conditions or the performance does not meet the standard requirements. The number of opening and closing cycles corresponding to the termination of the previous check is the number of static pressure life test.