1. LHC IRQ Tie Bar Redesign Using Sleeves – Preliminary
T. Nicol
May 25, 2007

2. Current tie bar installation

3. Preliminary analysis
Assumed vacuum load: 20,000 lb total or 5,000 lb per rod (89,000 N)
Maximum distance between vacuum vessel ears: 81” (2050 mm)
Assume pinned ends
Assume S.F. of 4
Pcr = p2EI/l2 = 20,000 lb
For stainless steel the minimum value for I = in4
Need ID = 1.25” to be compatible with current geometry
Solving for OD yields OD = 1.86” so use 2”
Actual I = 0.66 in4 so S.F. ~ 5.6

4. Attachment to existing ear

5. Attachment to sliding sleeve

6. Attachment to existing ear

7. Attachment to existing ear
At the magnet ears, the tie bar attaches with a 30 mm bolt. The bronze to stainless interface slides during pressure loading.

8. Attachment to sliding sleeve
Each tie bar joins at the sliding sleeve ear. This is where each is adjusted for length, preloaded slightly, then locked in position.

9. Typical assembly of two tie rods at each ear location

10. Typical assembly of two tie rods at each ear location

11. Typical tie rod assembly
Tie rod sleeve – 2” OD, 1.25” ID
Threaded insert – 30 mm thread ID, 42 mm thread OD
Insert – 30 mm thread ID, 42 mm smooth OD
Jam nut

12. Tie rod assembly using sleeves – v2

13. Typical assembly – v2
Outer nut omitted to prevent excessive load in the event of a cryogen spill inside the vacuum vessel

14. Typical assembly – v2 Nut to tighten sleeve against intermediate ear
Nut to tighten assembly against vacuum vessel ear
2” OD, 1.25” ID sleeve
Tie rod, nuts, and spherical washers are the same as those in the current system
Spherical washers
Tie rod

15. Typical assembly – v2

16. Typical assembly – v2

17. Typical assembly – v2

18. Q3 to DFBX tie rod assembly using sleeves – v2

19. Q3 to DFBX typical assembly – v2

20. Q3 to DFBX typical assembly – v2

21. Q3 to DFBX typical assembly – v2

22. Q3 to DFBX typical assembly – v2

23. Q3 to DFBX typical assembly – v2

24. Q1 to Q2 tie rod assembly Typical end detail MB-390923 (420 mm sleeve)
30 mm tie rod
Typical end detail
Spherical washers (2 pairs)
30 mm hex nuts (2)
30 mm jam nut (1)

25. Q2 to Q3 tie rod assembly Typical end detail MB-390924 (620 mm sleeve)
30 mm tie rod
Typical end detail
Spherical washers (2 pairs)
30 mm hex nuts (2)
30 mm jam nut (1)

26. Q3 to DFBX tie rod assembly
MB (682 mm sleeve)
30 mm tie rod
Stiffener plates (2)
Typical end detail
Spherical washers (2 pairs)
30 mm hex nuts (2)
30 mm jam nut (1)