Gerardo M., Kyle R.

Following the recent LGV11 actuation failure, analysis and recovery (here is a good place to recap -> https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=42304), the Project Vacuum Team concluded that all legacy 44" electrically actuated gate valves (at both sites) would need to be visually inspected.  This process was started and is continuing as opportunities present themselves (maintenance days).  Today we inspected WGV15, WGV14, WGV9, WGV10, WGV17 and WGV18. 

Today's results are potentially troubling -> Both SET SCREWS in the CLUTCH BODY of WGV10 were found to be very loose -> I tightened these (2 turns) but was torque-limited to a few inch*pounds by the L-key used.  I don't have a torque specification even if I did have the proper tool.  Also, the clearance between the RETAINING NUT and LIMIT SWITCH PULLEY was noticeably greater than that of the other valves.  By chance, one of the two DRIVE SHAFT BALL NUT SET SCREWS was accessible on WGV14 and it was found to be quite loose -> This was tightened using an L-key to a few inch pounds.  The CLUTCH BODY of WGV17 differed from any of the other units seen thus far in that its SET SCREWS are oriented (machined) at 90 degrees to each other versus 180 degrees for the other units.  Finally, WGV18's CLUTCH PRE-LOAD was at "8" on the graduated scale.  This compares to the more typical values of 4 or 5 -> This may be due to the placement of the graduated scale on this unit and may not translate into a meaningful PRE-LOAD difference as the number of exposed thread crests seen is typical of the other units. 

The archived results of these inspections is kept in the DCC in Q1800019 (thanks Stephen A.).