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Vacuum (Mode cleaner)
Vacuum, Gherardini - 14:59 Thursday 22 March 2018 (40725) Print this report
MC and IB restart

In the past days we completed the leak test of MC and IB towers, following the upgrade of the pumping circuits (related logentry )

The leak test of the newly added parts passed, the test was then extended to other chambers sections and two leaking defects were found:

1) MC tower, at the level of lower virola flange (= a pre-esisting known leak) LR ~ 1E-5 mbar.l/s. With respect to the vacuum level in central area, its influence is mitigated by the presence of the MC pipe and its repair is not considered mandatory.

2) MC pipe , at the level of the pumping port #3 (it is the port on the right side in the attached picture). Estimated position of the defect on the port =  weld between the main pipe and the pumping port itself (SW side). Leaking rate ~ 2E-5 mbar.l/s .

The leak is likely present since the beginning of AdV and needs to be closed to reach the final AdV vacuum level. Normally it shall be corrected by substituting the entire part = 5.5m long section flanged at extremities (while the on-site repair = re-welding could be attempted in case of availability of a long time slot  > 1 week).  The repair shall be planned when convenient for the general schedule, and could be postponed after O3.

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