To follow up on the "Apparent Y-1 leak" entry made last night:

Today I found a very large (~1x10-4 torr*L/sec) air leak on the 1.33" conflat flange at the valve body/annulus piping interface on the south side of GV9.  I also  found a lesser (~3x10-7 torr*L/sec) leak on the 2 3/4" conflat flange located on the gate side of the 1.5" all-metal gate annulus isolation valve -> 

*Hard-Closed GV9 
*Isolated and vented gate annulus piping 
*Replace gasket on leaking 1.33" conflat joint 
*Cinched-up flange fasteners on leaking 2 3/4" conflat joint 
*Pumped and recombined vented volume to rest of annulus 
*Opened GV9 

I am leaving the leak detector connected and valved-in to GV9's annulus system overnight tonight.  I will do some sensitive leak checking tomorrow.  



NOTE TO ALL
 
We have many original "legacy" bolted joints on the vacuum system throughout the site.  Though these have stood the test of time up to this point, they may still be vulnerable to being mechanically or thermally exercised, bumped, flexed and the like.  Please be cautious and conciensus when your work requires contacting bolted vacuum joint/flanges.