1. Cutting and welding
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017
G. Favre / A. Amorim Carvalho
G. Favre EN-MME

2. First internal LHC Dipole Diode Insulation Consolidation Review
Project overview
1232 diodes to be consolidated
2464 covers to be opened and re-welded
30 weeks (May to Dec. 2019) for cutting operations
30 weeks (July 2019 to Feb. 2020) for welding operations
Intervention team
Project management : engineer (EN/MME) as of now
Covers cutting (and covers machining when required): 6 mechanics (EN/MME)
Covers tacking and re-welding: welders (EN/MME)
Welding quality control : technicians for welding inspection (notified Body)
Traceability: technician BE/OP (2 technicians/50% each)
1 administrative student (as LS1) new request
13 FTE prod
4 FTE QA
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

3. First internal LHC Dipole Diode Insulation Consolidation Review
Project overview
Work organisation
Single train
Work on 4 fronts in parallel (4 interconnects)
6 efficient working hours per day
10 diode containers opened and closed per day
Drawings
Welding map: LHCMB__S0268
Covers: LHCMB__S0130 & LHCMB__S
Diode container: LHCMB__S0129
Tee : LHCMB__S0128
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

4. First internal LHC Dipole Diode Insulation Consolidation Review
Info/lessons learned from the series prod.
Welding process used by the 3 manufacturers (Alstom, Ansaldo, Noell)
TIG manual welding
without filler metal
Welding qualifications: complete for Alstom (WPQR, WQ), info. not found for Ansaldo&Noell
Weld throat depending of the manufacturer: a=2 for Ansaldo&Noell, a=1 for Alstom
Q: What was the throat thickness really obtain for the series production ?
Controls : Visual inspection, pressure and leak tests
WPQR Alstom
1 mm
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

5. Info/lessons learned from the previous consolidations
(dipoles & quadrupoles)
Covers cutting
Orbital cutting machines
Axial machining better than radial machining (less lips consumption)
One set available TE/MSC
Radial
Axial
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

6. 255 dipoles already opened 1 time
Info/lessons learned from the previous consolidations
(dipoles & quadrupoles)
Unchanged internal volume
Nominal position
1st cut: -2.5 mm
255 dipoles already opened 1 time
2nd cut: -5 mm
3rd cut: -7.5 mm
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

7. Info/lessons learned from the previous consolidations
(dipoles & quadruoples)
After few cuts (3 ? TBC), the groove in the covers has to be re-machine. In some cases covers may have to be changed.
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

8. Info/lessons learned from the previous consolidations
(dipoles & quadrupoles)
In case of new cover installation, the internal volume of the diode container will be affected. The compatibility with the insulation has to be checked (enough room?)
with new covers
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

9. Info/lessons learned from the previous consolidations
(dipoles & quadrupoles)
1 mm
Covers welding
Manual welding
Necessity to distribute the gap before welding (ovalization facing the Tee necking, gap up to 1 mm locally)
> Importance of the tack welding operation to ensure the weld quality
Filler metal was often used
Diode container dimensions w.r.t nominal
Diode container internal diameter out of tolerance (up to 0.5 mm)
Variation of the thickness along the diameter (i.e. from 1.6 mm to mm, nominal 2 mm)
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

10. Open points (1/2) Define the weld size (throat)
2 mm difficult to reach (even with the use of filler metal)
FEM to be done to define the minimum throat acceptable (see next slides)
Chose the appropriate welding method
Option 1: Manual welding with or without filler metal (solution used to date)
PRO: Less demanding with respect to the joint preparation (possibility to accommodate significant gaps, and defects)
CONS: Reproducibility of the result depend of the welder
Option 2: Orbital welding without filler metal
PRO: Reproducibility
CONS: Demanding regarding the joint preparation (limited gap allowed)
CONS: use of filler metal would be (very) difficult
Would be the best solution
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

11. First internal LHC Dipole Diode Insulation Consolidation Review
Open points (2/2)
Check the effect of the weld on the new electrical insulation
Max. temperature reach during welding. Previous SMACC experience on quad diodes consolidation shows that there are solutions for the insulation to be compatible with the temperature increase generated by the welding
Diminution of the internal volume in case of new cover installation
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

12. Numerical assessment Study objectives: Minimum cover thickness?
Minimum size of the throat a?
1st cut
3rd cut
5th cut
1mm ?
10.5
Pressure vessel + cryogenic application
Comprehensive approach needed.
Norm EN 13445: 3 Unfired Pressure Vessels
Weld case (joined lips) is not compliant.
Proposal (with acceptance from HSE):
Annex C: Design by analysis – Method based on stress categories
Annex T: Design by experimental methods of the weld in an equivalent structure
A. Amorim Carvalho
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

13. First internal LHC Dipole Diode Insulation Consolidation Review
Numerical assessment
1mm ?
Local stress concentration
Linearization of different paths: analysis of the worst case scenario
Assessment to be performed for the configurations:
1st cut (- 2.5mm) & 5th cut (- 12.5mm)
Considering different weld sizes: 0.5mm, 1.0mm, 1.5mm and 2mm
A. Amorim Carvalho
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

14. First internal LHC Dipole Diode Insulation Consolidation Review
Numerical assessment
Impact of the gap between the cover and tube will also be assessed
Gap can go up to 1mm
A. Amorim Carvalho
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

15. First internal LHC Dipole Diode Insulation Consolidation Review
Diode consolidation workflow
Mirko Pojer
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

16. First internal LHC Dipole Diode Insulation Consolidation Review
Workflow including QC steps & traceability
Covers cutting
Engraving of covers to keep the traceability w.r.t. the diode container
Dimensional control of the diode containers: ovalization, wall thickness, number of cuts already done in the past, etc.
Covers machining (when required) : level of activation? marching in RP workshop bldg. 109? HSE input required
Diode consolidation with dedicated tests & controls and traceability (electrical, cleanliness, pictures of the inside, etc.)
Green light for covers re-welding
Covers installation: gap distribution and tack-welding
Covers welding: welding parameters will be registered
Quality control of the welds: visual inspection (video registering)
Production of witness samples: control of the weld size and compactness (micrographs)
Local leak test using clamp shell tooling
Pressure test
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

17. First internal LHC Dipole Diode Insulation Consolidation Review
Next steps
Welding and cutting tests on representative samples
Validation of the weld throat thickness with HSE
Select the appropriate welding method (automatic or manual)
Qualifications: cutting & welding
Define the acceptance criteria for the welds acceptation (visual inspection)
Procurement of the equipment for the series prod.
Procurement of covers spares …
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

18. First internal LHC Dipole Diode Insulation Consolidation Review
Time scale
G. Favre EN-MME
First internal LHC Dipole Diode Insulation Consolidation Review
10 Oct 2017

19. Thank you for your attention
Questions?
G. Favre EN-MME