MSC Technical Meeting 29 August 2013

MSC Technical Meeting29 August 2013

Overheated splice @ QBBI.A21L6

F. Savary with contributions from N. Dalexandro,H. Prin, C. Scheuerlein, P. Voisin

Overheated splice @ QBBI.A21L6 2

Outline

The facts Proposed work plan

Intervention workflow

Description of the repair procedure

Description of the consolidation procedure

Schedule

Status of tooling

Conclusion

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The facts Observations in the tunnel in the end of May 2013 (WISH) NCR launched on June 10th, 2013, M2 Int.: https://

edms.cern.ch/document/1290623 As observed by LMF-QA the disconnected cable has been

severely damaged during installation (5 cut strands on the left side, and possibly signs of overheating on both sides)

The splice is part of a 1.9 K resistance outlier segment

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Overheated splice @ QBBI.A21L6 4

Measurements @ cold

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Rmeas=4.75nΩRmax=2.25nΩ

Courtesy Z. Charifoulline

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Reminder Subject discussed at the LHC Splices TF

Meeting #68, on 30 July 2013 See ref. EDMS 1304524

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Intervention workflow

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NCREDMS 1290623

Extract strands for magnetization measurements

• Unsolder M2 Ext., and the spool cables

• Cut / remove the bellow (Left)

• Cut / remove the flange, and spider clamp (Right)

• Remove insulation as needed• Cut / remove ~ 60mm of

copper to check the cable• Possibly, do radiographic

examination

Cable inspection:• Visual• Magnetization

measurements

Cable ok ?

Repair / redo the splice according to new procedure

• Cut / remove more copper, i.e. additional 60mm (only left side)

• Put in place shunts• Re-weld spool

cables• Put in place

standard insulation

YES

NOIn addition to

standard QC, carry out radiographic

examination

Cable ok ?

YES

NOReplace the magnet(s)

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LS1 Committee, 13th Meeting, 21 June https://indico.cern.ch/conferenceDisplay.py?confId=257962

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Courtesy C. Scheuerlein

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The environment & space limits

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45 mm

Splice opening & preparation work

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45 mm

30 mm

tbd

120 mm

50 mm60 mm

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Splice reconstruction

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150 mm + 2 x 60 mm (up to 330 mm, in case left side needs to be extended farther)

Smooth blending and overlap, avoid 2 mm step and sharp edges

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Cut / remove Cu around the cable

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Cut / remove Cu around the cable

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Reconstruction

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Reminder Force @ rupture, and resistance of a splice, both @

4.3 K, as a function of the overlap Note CERN-ATS-Note-2011-074, EDMS 1159508, by

C. Scheuerlein et al.

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The splice proposed for the overheated

cable is in this range

Courtesy C. Scheuerlein

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2009 – QBBI.B29R3 – M3 line

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Carry out ELQC, apply standard checks R8 standard, and R16 becomes R16+12

Cu machining, and shunt installation procedures are standard (as this is a quad. line, @ bottom only)

Insulation needs to be rebuilt in the 60 mm extensions of the splice (50% overlap, pre-preg, …), then the standard insulation system can be put in place

Consolidation procedure & QC

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August September October

W34 W35 W36 W37 W38 W39 W40 W41 W42

Procedure to remove Cu / 60mm xxxxx xxxxx xxx__

Inspection procedure, visual, magnetization measurements … actually nothing to do

xxxxx

Procedure to make special splice, including tests (elqc, radiographs, cuts & macros)

xxxxx xxxxx xxxxx

Preparation work in the tunnel xxxxx

Development of special insulation / spider xxxxx xxxxx

Inspection in the tunnel, and tests on the surface (magnetization measurements, …)

xxxxx

Reconstruction of the splice / QC [if cable ok!] xxxxx

Welding of a new bellow / M-flange / QC xxx__

Cu machining and shunt installation / QC __xxx

US welding of the spool cables / QC xxx__

Insulation / Injection / QC __xxx

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This week

Schedule

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Status on tooling For preparation

Almost finished Induction loop for unsoldering to be optimized,

utilization of tooling recovered from ACCEL (already utilized for the construction of the Q7)

For reconstruction Soldering molds to be designed and fabricated

For testing ELQC, ok Radiographic examination, should be ok [to be

checked with Jean-Michel Dalin]

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To understand it better Understand in what conditions there is

overheating Organize the execution of tests on the

surface Heat up a splice + bb progressively, and check

the effect on the copper parts, and insulation (oxidation, color, …)

This will help on deciding what to do in the other cases Statistics in preparation by Sandrine

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Conclusions A repair (special splice) is feasible It allows installing the standard shunts, and the standard insulation

system, but not the standard clamp (spider) on the right side Special tooling is needed for the preparation work (induction), and

for the re-soldering (resistive). However, not a major issue The repair is only possible if the cable is sane in the 60mm on the

right side, and in the 60mm or 120 mm on the left side of the original splice We rely on both top & bottom contacts of the 60 mm splice to get an

“almost” standard splice in terms of overlap If the above conditions are not fulfilled, one (or two) magnet(s)

has(have) to be replaced A special splice is also possible if only one magnet is replaced

The repair procedure allows intervention on any type of IC, QBB, QQB, and QBQ, and on any line (M1, M2, and M3)

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To be checked … With magnet coordination, what magnet can

we put in place, in case the cable is excessively degraded?

How many magnets do we have available in case there would be other cases?

Statistics (# of known cases of overheated cables) will be shown at the SMACC Meeting of next week

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