Engineering Division1

Vacuum Vessel Production Readiness

Review

July 29, 2009

Allan DeMelloLawrence Berkeley National Lab

Muon Ionization Cooling Experiment (MICE)

Radio Frequency/Coupling Coil Module (RFCC)

Engineering Division2

MICE Beamline

Engineering Division3

Radio Frequency/Coupling Coil Module (RFCC)

Engineering Division4

RFCC Quarter Section View

Engineering Division5

Vacuum Vessel Exploded

Major Components of the Vacuum Vessel

Engineering Division6

• 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

Overview of Fabrication Procedure

Engineering Division7

Rolled Cylinder

Engineering Division8

Fabrication of Vacuum Vessel Flanged Section

Engineering Division9

Vacuum Vessel to Coupling Coil Gussets

•Remove vessel section from the coupling coil and complete the welding of the gussets to the vessel

Tack weld a stainless steel bar across the gusset pairs to help maintain their position

Align gussets to coupling coil and tack weld to vacuum vessel

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Final Machining of Vessel Section

Engineering Division11

Weld on Strut Mounting Posts

Engineering Division12

Vacuum Vessel Central Sleeve

•Precision machined central sleeve•5.08mm (0.200 in.) wall thickness•1384.93mm O.D.•1374.77mm I.D.

Engineering Division13

Assemble Vacuum Vessel and Weld

Engineering Division14

Weld on Manifold and Feedthroughs

Vacuum Vessel and Coupling Coil Assembly

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Vacuum Vessel Assembly Fixturing Scheme

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Vacuum Vessel Analysis

Engineering Division17

• 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

Vacuum Vessel Analysis

Engineering Division18

Thin Walled Cylinder Stress - 0.200 inch

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Thin Walled Cylinder Stress - 0.500 inch

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Length

÷ O

uts

ide D

iam

ete

r =

L/

Do

Outside Diameter ÷ Wall Thickness = Do/t

Factor A

Factor A

Fact

or

B

Charts used to find Factor A and Factor B which are used in ASME Boiler and Pressure Vessel Code Calculations

ASME Boiler and Pressure Vessel Code

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Minimum Wall Thickness(2007 ASME Boiler and Pressure Vessel

Code)

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Design Verification – External Pressure(2007 ASME Boiler and Pressure Vessel

Code)

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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)

Engineering Division24

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

Code)

Engineering Division25

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

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ANSYS Analysis

ANSYS Analysis

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Vacuum Vessel w/o Coupling Coil

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Model of Vacuum Vessel for ANSYS

•14.7 psi external pressure applied to stainless steel vessel

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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

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Model - Vessel With Gussets Added

•14.7 psi external pressure applied to stainless steel vessel

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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

Engineering Division32

Bellows Bridge Bolts

•Bridge bolts are needed to transmit the potential 50-ton magnetic force when the magnet quenches

Bridge bolts – exterior view

Bridge bolt – section view

•36 - ten millimeter bolts will bridge the RFCC to AFC bellows

Bellows pulled back for module clearance

Engineering Division33

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

Engineering Division34

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

Engineering Division35

Tilting of Vacuum VesselThe 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

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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 0.375 thick aluminum• The force of gravity is applied

6867 psi equivalent stress is well below yield stress for 316L stainless steel of 42000 psi

Engineering Division37

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

Lifting of RFCC Assembly

Engineering Division38

Lifting the RFCC Assembly – ANSYS Results

10161 psi equivalent stress is well below yield stress for 316L stainless steel of 42000 psi

• 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 0.375 thick aluminum• The force of gravity is applied

Engineering Division39

• 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

Summary

Engineering Division40

Thank You