1. Vacuum Vessel Production Readiness Review
Muon Ionization Cooling Experiment (MICE)
Radio Frequency/Coupling Coil Module (RFCC)
Vacuum Vessel Production Readiness Review
Allan DeMello
Lawrence Berkeley National Lab
July 29, 2009

2. MICE Beamline

3. Radio Frequency/Coupling Coil Module (RFCC)

4. RFCC Quarter Section View

5. Vacuum Vessel Exploded
Major Components of the Vacuum Vessel

6. Overview of Fabrication Procedure
Fabricate of vacuum vessel in 3 sections – two 316L stainless steel flanged sections and one 316L stainless steel central sleeve
Assemble 3 vacuum vessel sections to the coupling coil (in appropriate fixturing)
Verify alignment of all vacuum vessel components
Weld all joints and gussets
Weld on the vacuum pump manifolds and RF feedthroughs
Leak check vacuum vessel

7. Rolled Cylinder

8. Fabrication of Vacuum Vessel Flanged Section

9. Vacuum Vessel to Coupling Coil Gussets
Align gussets to coupling coil and tack weld to vacuum vessel
Tack weld a stainless steel bar across the gusset pairs to help maintain their position
Remove vessel section from the coupling coil and complete the welding of the gussets to the vessel

10. Final Machining of Vessel Section

11. Weld on Strut Mounting Posts

12. Vacuum Vessel Central Sleeve
Precision machined central sleeve
5.08mm (0.200 in.) wall thickness
mm O.D.
mm I.D.

13. Assemble Vacuum Vessel and Weld

14. Weld on Manifold and Feedthroughs
Vacuum Vessel and Coupling Coil Assembly

15. Vacuum Vessel Assembly Fixturing Scheme

16. Vacuum Vessel Analysis

17. Vacuum Vessel Analysis
Calculate stress for thin walled pressure vessel
Analyze vacuum vessel per 2007 ASME Boiler and Pressure Vessel Code VIII, Division 1
ANSYS analysis for vessel with external pressure
ANSYS analysis for the 50-ton magnetic load
ANSYS analysis for tilting to horizontal position
ANSYS analysis for lifting from four points

18. Thin Walled Cylinder Stress - 0.200 inch

19. Thin Walled Cylinder Stress - 0.500 inch

20. ASME Boiler and Pressure Vessel Code
Charts used to find Factor A and Factor B which are used in ASME Boiler and Pressure Vessel Code Calculations
Outside Diameter ÷ Wall Thickness = Do/t
Length ÷ Outside Diameter = L/Do
Factor B
Factor A
Factor A

21. Minimum Wall Thickness
(2007 ASME Boiler and Pressure Vessel Code)

22. Design Verification – External Pressure
(2007 ASME Boiler and Pressure Vessel Code)

23. Design Verification – Internal Pressure
(2007 ASME Boiler and Pressure Vessel Code)
A burst disc will be installed on the vessel to avoid the possibility of over-pressure (25psi max)

24. Design Verification – External Pressure (1/3 Vessel)
(2007 ASME Boiler and Pressure Vessel Code)

25. Design Verification – External Pressure
(2007 ASME Boiler and Pressure Vessel Code)

26. ANSYS Analysis
ANSYS Analysis

27. Vacuum Vessel w/o Coupling Coil

28. Model of Vacuum Vessel for ANSYS
14.7 psi external pressure applied to stainless steel vessel

29. ANSYS Results - Equivalent Stress
14.7 psi external pressure applied to stainless steel vessel
1888 psi maximum equivalent (von Mises) stress
Maximum allowable stress for 316L stainless steel from ASME Boiler and Pressure Vessel Code is 16,700 psi
Weld efficiency of 60% reduces the maximum allowable stress to 10,020 psi
With the de-rated welds the maximum stress is 5.3 times less than the maximum allowable stress

30. Model - Vessel With Gussets Added
14.7 psi external pressure applied to stainless steel vessel

31. ANSYS Results - Equivalent Stress
14.7 psi external pressure applied to stainless steel vessel with gussets
2041 psi maximum stress
Weld efficiency of 60% reduces the maximum allowable stress to 10,020 psi
With the de-rated welds the maximum stress is ~5 times less than the maximum allowable stress

32. Bellows Bridge Bolts
Bellows pulled back for module clearance
Bridge bolts – exterior view
Bridge bolts are needed to transmit the potential 50-ton magnetic force when the magnet quenches
36 - ten millimeter bolts will bridge the RFCC to AFC bellows
Bridge bolt – section view

33. Model – Vessel with Bridge Bolts
36 bolts in flange
Stand fixed at base pads
Vessel fixed at bolt face
50-ton load applied to coupling coil

34. 50 Ton Magnetic Force -36 Bridge Bolts
A 50 ton force is applied to the coupling coil
The vacuum vessel has an increased density to simulate the presence of the cavities
36 bridge bolts per side to transfer the load to the rest of the MICE beamline.
von Mises max stress of 32,263 psi on bolt cross section
Strain hardened 316L stainless steel bolts which have a yield strength of 100,000 psi (minimum) will be used to bridge the bellows

35. Tilting of Vacuum Vessel
The vacuum vessel will be tilted from the vertical (operational) position to the horizontal (shipping) position. It will be tilted back again to the operational position in the U.K.
RF cavities are removed for shipping

36. ANSYS Analysis - Tilting of Vacuum Vessel
The vacuum vessel is modeled in ANSYS to simulate hanging from 2 of the pick points.
The cavities are assumed to be removed.
Ends of vacuum vessel are capped with thick aluminum
The force of gravity is applied
6867 psi equivalent stress is well below yield stress for 316L stainless steel of psi

37. Lifting of RFCC Assembly
Anticipating the possibility that the complete RFCC module will be lifted using the 4 pick points provided for tilting the assembly - an ANSYS analysis of the lifted assembly was done

38. Lifting the RFCC Assembly – ANSYS Results
The vacuum vessel is modeled in ANSYS to simulate hanging from the 4 pick points.
The cavities are assumed to be in place.
Ends of vacuum vessel are capped with thick aluminum
The force of gravity is applied
10161 psi equivalent stress is well below yield stress for 316L stainless steel of psi

39. Summary
Because of the tight interface between the O.D. of the vacuum vessel and the I.D. of the coupling coil the vacuum vessel is assembled from three major parts
The two flanged section are fabricated in several steps to minimize the distortion of the welding
The central sleeve is precision machined to guarantee it will fit into the coupling coil I.D.
Analysis verifies the ability of the vacuum vessel to withstand the vacuum loads
Strain hardened 316 stainless steel bridge bolts will be needed to transfer the magnetic loads through the bellows joint
Tilting and lifting are possible with this design

40. Thank You

41. Vacuum Vessel w/o Coupling Coil

42. Vacuum Vessel – Section View

43. Total Deformation

44. Total Deformation

45. 50 Ton Magnetic Force – ANSYS Results

46. ANSYS Results – Equivalent Stress
Support stand only
14.7 psi external pressure applied to stainless steel vessel with gussets
Gravity
4150 psi maximum stress

47. Ends of vacuum vessel are capped with 0.375 thick aluminum

48. 50 Ton Magnetic Force -18 Bridge Bolts
A 50 ton force is applied to the coupling coil
The vacuum vessel has an increased density to simulate the presence of the cavities
18 bridge bolts per side to transfer the load to the rest of the MICE beamline.

49. ANSYS Results – Equivalent Stress
14.7 psi external pressure applied to stainless steel vessel with gussets
Gravity
4150 psi maximum stress (in the stand)

50. ANSYS Results – Equivalent Stress
Vacuum vessel only
14.7 psi external pressure applied to stainless steel vessel with gussets
Gravity
3361 psi maximum stress
Weld efficiency of 60% reduces the maximum allowable stress to 10,020 psi
With the de-rated welds the maximum stress is ~3 times less than the maximum allowable stress