1. 2K Cold Box Structure Analysis
Shirley Yang
LCLS-II 2 K Cold Box PDR
September 27, 2016

2. Outline Material Properties Boundary Conditions Stress Result
Deformation Result
Buckling
Center Column
Nozzle Reinforcement
Conclusion
LCLS-II 2 K CBX PDR, Sept 27, 2016

3. 2K Cold Box Structure
2K cold box structure is analyzed per PART 5 Design by Analysis Requirements of ASME Section VIII, Division 2.
12’ OD 2” thick top plate; SA240, 304 SS.
12’ OD 1 1/4” thick top skirt; SA240, 304SS
12’ OD 3/4” thick shell; SA516 Gr. 70, CS.
12’ OD 3/4” thick bottom head; SA516 Gr. 70, CS.
12’ OD 1/2” thick bottom skirt; A36, CS.
LCLS-II 2 K CBX PDR, Sept 27, 2016

4. Material Properties - ASME Section II Part D
304 SS RT
Young’s Modulus (psi)
2.80E+07
Poisson’s Ratio
0.29
Density (lb/in^3)
SA516 CS RT
2.90E+07
0.26
0.28
RT = room temperature
LCLS-II 2 K CBX PDR, Sept 27, 2016

5. Allowable Stress Per BPVC S8
The table below lists the allowed stresses for each stress category as defined in the BPVC, S8, Div. 2, paragraphs (e) and (d).
Allowable Stresses for Each Stress Category (psi)
Material
Stress Category Pm PL
PL + Pb
PL + Pb + Q
293K
SA240, 304SS
20,000
30,000
60,000
SA516 Gr. 70
25,300
37,950
75,900
Pm = primary membrane stress ≤ S (per BPVC S8D2 paragraph (e))
PL = primary local membrane stress ≤ 1.5×S (per BPVC S8D2 paragraph (e)
Pb = primary bending stress
Q = secondary stress
(PL + Pb) ≤ 1.5×S (per BPVC S8D2 paragraph (e))
(PL + Pb + Q) ≤ 3×S (per BPVC S8D2 paragraph (d))
LCLS-II 2 K CBX PDR, Sept 27, 2016

6. Boundary Conditions – Normal Operation Condition
Vacuum is applied to the inner surfaces of the top plate, shell, and bottom plate.
The weight of unit motor and compressor, as well as 10% of this weight which represents the estimated weight of the piping system, are applied to CC0 to CC5, respectively.
LCLS-II 2 K CBX PDR, Sept 27, 2016

7. Boundary Conditions – Normal Operation Condition Continuous
3. It is assumed that two 20” jacketed trunk lines will be supported 10 ft away from the vessel. Two remote forces are added 5 ft away
from the top two opening areas. The weight of the manway is too small to be considered.
4. Forces of lbf and 4620 lbf caused by vacuum on openings are applied to the manway and 20” jacketed line areas.
5. 8” NPS sch 40 pipe supports in the center of the vessel between the top and bottom heads.
6. A Standard earth gravity is applied to the model.
7. The bottom skirt surface is fixed.
LCLS-II 2 K CBX PDR, Sept 27, 2016

8. Von-Mises Stresses 20 ksi is the allowable stress.
Red color indicates that the stress on the region is larger than 20 ksi.
Only a few tiny areas have a stress larger than 20 ksi. And this is because of stress concentration. We can ignore them.
LCLS-II 2 K CBX PDR, Sept 27, 2016

9. Deformation
The maximum deformation is 0.16”, which is located in the compressors CC4 and CC5 area. But the “relative” deformation in each compressor area is less than the required tolerance, which is 1/16”.
LCLS-II 2 K CBX PDR, Sept 27, 2016

10. Vessel Buckling
Buckling modes were checked for the vessel since it is under the vacuum at the normal operation condition. The minimum safety factor is Therefore, buckling is not a concern for the vessel.
LCLS-II 2 K CBX PDR, Sept 27, 2016

11. Thermal and structure Consideration of the Center Column
In order to reduce the shrinkage of the center column, a 1/8” thick copper tube will be inserted to the column. By doing it, per calculation, the column only shrinks 0.02 inch. In addition, a 18” diameter x 1/2” thick plate and a 30” diameter x 3/4” thick plate will be installed on the top and the bottom of the column respectively so that the load can be evenly distributed. Spider ribs are also needed at the bottom of the plate.
LCLS-II 2 K CBX PDR, Sept 27, 2016

12. Thermal and structure Consideration of the Center Column - Continuous
From the FEA, the center column will take lbf of compression load along its axial direction. The calculated buckling load is lbf. Therefore, the buckling of the center column is not a concern.
LCLS-II 2 K CBX PDR, Sept 27, 2016

13. Nozzle Weldment and Reinforcement
LCLS-II 2 K CBX PDR, Sept 27, 2016

14. Nozzle Weldment and Reinforcement Continuous
LCLS-II 2 K CBX PDR, Sept 27, 2016

15. Nozzle Weldment and Reinforcement Continuous

16. Conclusion
Structure design of the vessel meets the requirements of ASME code.
The center column will be heat intercepted with copper layer insert to reduce the thermal shrinkage.
Double fillet lap joint will be used to weld nozzles to shell.
No reinforcement pad is required on openings.
LCLS-II 2 K CBX PDR, Sept 27, 2016