Joint repair continues.

Leak Check:

- Local leak check performed around area of T2, M9-Q1. All seals other than T2 Q1 were leak tight. Largest source of leak was the T2 Q1 joint area.

- Leak check done in quadrants around joint, response times were <2 sec of applying helium. Leak detector also responded when He probe was near joint (before actually applying He).

Video and Physical inspection:

- Bottom weld lug bolt found in tension/captive (ie. not free to move). Confirmed static by poking bolt. (Videos of this in RH group folder).

- Top weld lug had > 0.2" of gap.

- East and West pins seen leaning slightly toward North (toward Q1).

Loading Test:

At 13:30 a load test was performed to observe the effects of loading nearby blocks around T2 (see photo). Two 12 x 6 x 3 shield blocks were stacked one on top of the other and vacuum was observed, one then the other. There was no observable effect on the vacuum each time. Bottom weld lug bolt was still frozen when poked.

Blocks were replaced to their original locations once test was complete.

The T2 volume was vented at ~14:15 in preparation for disassembly to be performed on Monday.

Today:

Bridge setup complete; Noticed 12 x 3 x 3 block when placed on top of several other blocks rocked when placed down.

Took initial photos of joint: west side approximately 0.05" to 0.06" gap, east side 0.20" to 0.220" gap. Joint appears to be the same as before. See photos.

Will do visual/video inspection and leak check tomorrow morning.

Remote Handling plus support groups are currently attempting to install and commission indium vacuum seals into the following M20 front-end joints:

- T2/Q1

- Q2/Scraper

- Scraper/T2

The first indium joint installed was at T2/Q1 during the week of May 14 to 18.  Rubber seals were installed at the other two joints.  The system was leak checked on Tuesday May 22 and a suspect leak response was detected. 

The details of the installation and the leak check are in the attached .pdf e-mail dated 23 May 2012.

Today (Thursday 24 May 2012) the T2 volume and M20 front-end vacuum system were leaked checked with rubber seals in all aforementioned joints by RH group and Vacuum Group.  The results are listed below:

The test equipment consisted of a long Remote Handling pole with a copper helium applicator line attached to the end, joined to a long plastic line extending up the pole to the RH operator above. 

The plastic line was kinked with a zip-tie to cut off the flow.  To engage the flow for each test, the zip-tie was removed and the kink was opened. 

This would result in a burst of helium of a pressure you could feel easily on your face for approximately ~1s followed by a steady, very low flow just detectable on the cheek / tounge. 

The Varian Leak Detector was used attached by Vacuum Group to the T2 and M20 front end volume.  Edi Dalla Valle monitored the leak detector and communicated to Ron Kuramoto via headset radio.

The test started at 11:15 am, 1ACG4 20mT, 1AVA8 closed.

1) M20 Beam Blocker Top Flange (Top of T2 Monument)

11:15 am

Base leak rate 1.5 x 10-8 atmcc/sec

10 second spray of helium

No response after 2 min.

2) M8 T2 Blank-Off Flange

11:30 am

Base leak rate 1.5 x 10-8 atmcc/sec

5 second spray

First reponse after 30 seconds

Peak at 2 minutes, 4.1x10-8 atmcc/sec

3) M20 Q1/T2 Flange Top-Dead-Center

Base rate 1.7x10-8 atmcc/sec

5 second spray

First response after 40 seconds

After 60 seconds, 2.5x10-8 atmcc/sec

Peak at 2 minutes, 3.3x10-8 atmcc/sec

Recovery beginning after 2.5 minutes

4) M20 Q1/T2 Flange Bottom-Dead-Center

Base rate 1.7x10-8 atmcc/sec

5 second spray

First response at 45 seconds

Peak at 3 minutes 3.0x10-8 atmcc/sec

*1ACG4 read 16 mTorr at 11:55 am

5) M9 Q1/T2 Flange Top-Dead-Center

Base rate 1.6x10-8 atmcc/sec

5 second spray

No response after 3 minutes

6) Downstream T2 / 1AQ14 (Collimator B Area, see attached photo of Ron Kuramoto applying helium at this area)

Base rate 1.5x10-8 atmcc/sec

5 second spray

First response after 10 seconds

3.3x10-8 atmcc/sec at 1 minute

Peak at 1m 45 sec 3.6x10-8 atmcc/sec

7) M20 Q2/Scraper

Base rate 1.6x10-8 atmcc/sec

5 second spray

First response after 2 minutes 1.7x10-8 atmcc/sec

Peak at 2.5 minutes 1.8x10-8 atmcc/sec

This leak check confirmed suspicions of helium drift to the known leak at T2 / 1AQ14 joint on the T2 monument. 

The delayed leak response seen on May 22nd at M20 T2/Q1 is very likely drift of helium to this known leak based on these measurements, and not an actual leak at T2/Q1.

Edi Dalla Valle re-confirmed these leak check results with standard remote helium line tests.  His notes for these tests are scanned and attached.

We will proceed tomorrow to make up the T2/Q1 joint with the same ring and pin combination as used May 17 to May 22 2012.

4" indium flanges at the 2C rad hard valve were cleaned of the remaining indium by C. Ballard. Both upstream and down stream flanges were done, ready for installation of new valve.

Reinstalled ceramic insulators #6 7 8 to Q1 magnet by C Ballard. #6 and 8 went on with no issues. The copper tubing on insulator #7 had to be bent to match the new position of the re-brazed #7 fitting. This may have been due to the removal of the inner and outer conductors (the two copper plates that clamp the two coils together) during yesterdays repair which shifted the position of the coil. See photos.

Old #7 coil fitting removed, replaced and re-brazed today by M Good. Insulators ready to go back on to magnet coils to be pressure checked.

Image P1020013.JPG shows #7 coil fitting before removal. Heat shielding in the form of small aluminum sheets were installed to protect the magnet and electrical wiring.

Image P1020028.JPG shows new #7 fitting with all tools removed from area.

Insulators # 6,7,8 removed from Q1 headers late afternoon by C Ballard. Ready for removal and re-brazing of #7 joint some time today.

Warm cell reconfigured for water leak repair at coil termination. Radiation surveys done. M20 Q1 ready for removal of insulators.

Attached photo of warm cell as of Tuesday morning.

dfdfdfdfdf