Fermilab requirements and recent FEA Analyses PH-DT Engineering Office, CERN 06/05/2015 Page 1 CERN, May 6th 2015

ASME code interpretation on allowable stresses. Comments from members of the Fermilab committee Concerning the outstanding issues on allowable stresses, etc. David has spoken with several members of the panel (directly and through a colleague of mine at Fermilab who was himself part of the panel). The design can be made according to any Code: ASME Section VIII Div. 1, Div. 2, ANSI/AISC 360, European steel building code, etc. However, as additional precaution and safety considerations, such design needs also to satisfy the following two conditions: a) The design with all applicable loads shall be verified with Finite Element Analysis to ensure a level of safety equivalent to that afforded by the current version of the ASME Boiler and Pressure Vessel Code, Section VIII Div. 1. Table 7.1 presents the current allowable stress limits per ASME Boiler Pressure Vessel Code, Section VIII, Div.1: the minimum of St/3.5 or Sy/1.5. b) For a support structure made of structural steel, the U.S. code ANSI/AISC “Specifications for Structural Steel Buildings” shall be used by a professional structural engineer to ensure tensile, shear, and compressive stresses do not exceed limits for design stresses given in Table 7.1, temperatures, and temperature differentials. This does not imply that such codes (ASME Section VIII Div. 1 and/or ANSI/AISC 360) need to be used for the design. ASME Section VIII Div. 2 can be used for the design of any and/or all parts of the structure. However the allowable stresses are to be taken from Table 7.1 of the document “FESHM Guidelines” for any part: steel beams, bolts, etc. The minimum of St/3.5 or Sy/1.5. Page 2

“Guidelines for the Design, Fabrication, Installation and Testing of Metallic Membrane Cryostats” Manufacturer or supplier of the metallic membrane cryostat shall be required to provide documentation for approval by Fermilab to be sufficient to complete an Engineering Note per FESHM and form FESHM TA. At a minimum, the following shall be required from the manufacturer of the metallic membrane cryostat: Solid model of a typical corrugated sheet Design stress calculations for membrane and support structure Load bearing calculations for the insulation Heat load calculations Drawings to support design calculations Material specifications and certifications to support design calculations Detailed assembly procedures Design for the insulation purge, including flow rate calculations and overpressure protection Detailed leak checking and testing procedures Calculations of relief valve sizing should follow appropriate standards such as American Petroleum Institute Standard API 2000 “Venting Atmospheric and Low-Pressure Storage Tanks”. Page 3

Steel Grades Steel S355 (EC properties for t>40mm) –σ y =335 MPa → σ y /1.5=223 MPa –UTS=470 MPa → UTS/3.5=134 MPa → UTS/2.4=195 MPa Small Improvements by moving to S450 (EC properties for t>40mm): –σ y =410 MPa → σ y /1.5=273.3 MPa –UTS=550 MPa → UTS/3.5=157 MPa → UTS/2.4 =229 MPa Page 4 24/04/2015

Static analysis results Page 5 NB: TBC but both ASME Div1&2 would allow (Pm+Pb) < 1.5 x Sallowed Stress and deflection for main candidate beams at new given length: HL : beam Pm+Pb = 141 Mpa

Static analysis results Page 6 Stress and deflection for main candidate beams at new given length: lighter HL : beam Pm+Pb = 155 MPa

Buckling analysis results – no bracings Page 7 Difficulties in assessing the contribution from the internal grid (FEA convergence, analytical limited) There are portions of the beam where the grid would not help (inverse moment at top/bottom, beams close to corners) Preliminary analysis ignoring the grid: HL

Buckling analysis results – no bracings Page 8 Preliminary analysis ignoring the grid: HL

Buckling analysis results – 3 bracings Page 9 SET TIME/FREQ LOAD STEP SUBSTEP CUMULATIVE

Buckling analysis results Page 10

Buckling analysis results Page 11

Buckling analysis results Page 12