Present: A. Andreazza, G. Darbo, F. Djama, K. Einsweiler, M.
Garcia-Sciveres, M. Gilchriese, D. Giugni, F. HŸgging, V. Kostyukhin, G.
Lenzen, A. Rozanov, E. Vigeolas.
1. Corrosion:
preparation of the next week workshop and actions
2. Production status
and test in the labs.
3. Half shell
modification.
4. Cabling (clips,
etc.).
5. Maurice's proposal
for using WiKi as reworking plan tool.
1.
Stave
pipe corrosion.
Eric briefly described the test he made on
the insertion of an aluminium pipe inside the existing stave pipe. A
description of the test and its result can be found in the document:
http://www.ge.infn.it/ATLAS/SQTF/Minutes/Minutes_05-08-11_aux/Leaky_Stave_Fix.pdf.
The test was
made by inserting a 200 mm pipe in a short section of a stave with a dummy
module heater loaded on. No thermal compound was applied between the two pipes
due to the high friction. The thermal measurements were made with different
heater powers (from 2.5 to 10 W). For 5 W the increase of temperature is in the
order of 2.5Ö3.0 ¼C. The power for a Module (before irradiation) is around 3.8
W, but at the end of the life and with the cables heat the budget power for
cooling is 8.5 W.
The result of
the EricÕs test is encouraging but many other issues must be addressed.
Giovanni recognized the activity of the Marseilles group in the looking for a
solution of the corrosion problem. The discussion that followed raised several
questions and comments:
-
What material for the pipe: aluminium?
Or stainless steel?
-
How to stop corrosion from outer tube
to the inner one? Coating or cleaning of all the corrosion cells in the
existing pipe is enough?
-
Coating seems very difficult being the
insertion too abrasive for any coating after a few centimetres of friction
between the two pipes.
-
Corrosion from galvanic cells of the
corroded pipe will propagate to the new pipe in case of aluminium.
-
Coating of the existing pipe without
the insertion of a new pipe is seen to be very difficult on corroded surface.
Coating must also consider the C3F8 fluid and radiation effects. Presence of H
in case of dissociation of C3F8 can generate hydrofluoric acid (HF) that is
very corrosive.
-
Measurements on a bi-stave with heater
and evaporative cooling must be performed to understand the overall degradation
in thermal performance.
-
Hydraulic diameter of the new tube is
3.9 mm from the 4.07 of the original.
-
Danilo did some preliminary Finite
Element Analysis to study the thermal behaviour coming from the insertion of a
pipe. He will provide results next days.
-
Insertion of a 80 cm long pipe in a
full stave has still to be tested. Also the right size must be selected, and
this should consider standard production pipes only.
Kevin shortly told us what are his ideas for the next week
(18-19/08/2005) ÒDedicated Workshop on Corrosion ProblemsÓ:
-
Workshop not too structured;
-
First day based on presentations,
second day on discussions;
-
Morning of first day: measurements
plus presentations form corrosion and chemistry experts;
-
Afternoon of first day: repair
scenarios.
In case of using a Òpipe-in-pipeÓ solution, there is the problem of
applying new fittings to the inner pipe. LBL will investigate the possibility
of gluing new fitting. Also effect of F3C8 on glue and irradiation will be
investigated. CERN will send few aluminium round pipes and fittings to LBL for
testing.
Stave loading is
suspended in all the sites. A total of 44 staves are completely loaded. The
updated table with the status of all loaded staves is:
http://www.ge.infn.it/ATLAS/SQTF/StaveProduction/Summary_All_050811.xls
Fabian has
summarized the status of the 15 staves that need MCC repair. A total of 3 are
repaired. A more detailed status of repair is summarized in the FabianÕs email:
http://www.ge.infn.it/ATLAS/SQTF/Minutes/Minutes_05-08-11_aux/Fabian_email
and in the
table:
http://www.ge.infn.it/ATLAS/SQTF/Minutes/Minutes_05-08-11_aux/Stave_repair_bonn.xls.
Sector
production is progressing fine, and thermal/power cycles on sectors with
encapsulated MCCs and FEs is progressing without showing failures. More
information is available in the MarianÕs email:
http://www.ge.infn.it/ATLAS/SQTF/Minutes/Minutes_05-08-11_aux/Marian_email.rtf.
Danilo reported
that the modifications on the half-shells were successfully. Modifications were
made by IVW at CERN using an handheld drill ad tools made at CERN.
Danilo reported
that cabling test of bi-stave would happen again the week of 22/8/2005 with the
presence at CERN of Wolfgang.
Maurice last
week proposed the use of WiKi as a tool for planning stave activities, see:
http://www.ge.infn.it/ATLAS/SQTF/Minutes/Minutes_05-08-11_aux/Maurice_email.rtf.
Maurice already prepared a skeleton of a
WiKi page to record bare stave activities:
https://uimon.cern.ch/twiki/bin/view/Atlas/StaveLoadingPlan.
Sasha found the
tool proposed by Maurice adequate for the job. Sasha also already added the
information of the staves in CPPM. We propose that responsibles of other sites
look at it and to take a decision at the next phone conference.
Danilo proposes
that the bi-weekly SQTF would suppressed until loading activities will be
resumed. Giovanni objected that not only loading is discussed in the phone
conference and it would be useful to maintain it. Decision was to have
Integration phone conference ran by Danilo weekly and suspend SQTF. Danilo will
circulate minutes after each integration phone conference to the Pixel collaboration
to keep it informed.
Next
SQTF phone conference when loading will be resumed.