1 QMUL Face to Face Meeting 2/2/2012 Richard French, Paul Kemp-Russell, Hector Marin-Reyes (Sheffield) John Matheson, Martin Gibson, Ian Wilmut (RAL) Ian Mercer (Lancaster) Richard Bates, Alexander Bildatze (Glasgow) ATLAS Upgrade WP4 task 2 cooling update Welding electrical effects, tube developments, welding & dissimilar joining, tube bending, component identification, cooling circuit pressure drop measurement.

Ti TIG Repeatability conclusions CP2 Titanium1/8”OD x 0.20mm wall 532 repetitive welds First 20 welds suffered from same lack of refinement as 316L process. Now understood and will complete 1000 welds by end of Feb Testing ready to go at CERN for random batch samples. OXIDE is still a problem! Regular cleaning is increasing repeatability. More attention is paid to the joint preparation. WPS being written. 2 The process is highly repeatable for both materials and now highly optimised. I need to check this again with a number of fixed tubes representing detector service connections then repeat the process for the CP2 Ti 2.275mm OD x 120um wall when happier with the weld itself. Internal gas purge pressure may be the tricky item to manage correctly during installation in the cryostat. CP2 Ti weld joint

3 – Flare one end of the tube to bring extra material into the overlapped joint. = 120μm + 120μm give a bulbous weld bead (now controlled to outside of tube by altering angle and depth of flaring tool) Welded joint wall of ~220um wall at highest measured point = straight tubeflared tube insert weld ~60μm Welding of CP2 Titanium 120μm wall tube Best butt weld joint in 2.275mm CP2 Ti – pin hole every time. – Can successfully join the 2.275mm OD x 120μm tube with orbital welding using the above process. Initial NDT results are underway (x-ray). Data returned (x-ray only) but not ideal as too many inclusions. – Need better cleaning methods. – This can be refined much further as not happy with visual results – Spending time understanding the gas purge pressures. Theory is that the pressure alters when the tube seals and is causing the pin hole. This looks to be evident when I attempted the same task in 2.0mm Stainless Steel. Best welded joint to date using new tooling to create sleeve joint. Still have a indentation from post weld cooling [pressure or cleanliness]

Welding development update Pressure drop measurements Working with Alexander Bildatze & Richard Bates GLA/CERN All 1.2 & 1.6m long cooling circuits now made (Ian Mercer – Lancaster) may steal some of the 2.275mm tubing to create more Stavelets or test pieces until new order ready. New production tests indicate the wall thickness is likely to be in the region of 0.110mm (nominal value). This does mean the OD is not as controlled as we hoped – this is due to the pickling process to remove the oxide. Order being constructed for fittings, valves etc. Cu blocks for heaters and assembly work will be done in Sheffield. First test pieces made and brazed in-house ok (ish) Final assembly and connection to PLC and plant at CERN. Early Welding development Fronius UHP weld head when used with Swagelok system proved marginally better in terms of alignment of tube than Swagelok counterpart. Still fiddly to use but no loose pieces for similar sized head (still large). No noticeable increase in performance, just easier to use. Gas purge connections and measurements should be simpler. Will look at using an automated pressure sensor and valve to completely remove error from the process. Experimenting with different purity shield gases used for Ti welding Experimenting with different electrode materials and tip angles. Electrode tip grinding direction makes a massive difference to electrode performance and life. Also cutting the electrodes instead of cropping the ends increases performance and life. Cleaning is now under investigation – how much do we need to do? 4

Electrical studies John Matheson is currently at CERN working with Jan Kaplon trying to blow up FEI4 chips. RAL M200 has been shipped to CERN and received by Ashley. This is using the 4H welding head. Assuming no news is good news. Hector is now starting to reproduce John’s initial system output measurements. Initial results convincing but need to refine the set up with a shunt and correct cabling 5

Tube bending and component identification Ian Mercer has currently bent pretty much everything required from the April 2011 list. It looks as if this requirement has now altered. The Fibremark laser etch system from Epilog laser looked promising for bar-code and number marking of cooling components. Tests at Epilog have proved that the 2mm ID tube is too small to reproduce a legible bar-code. Tube cutting (in-situ) is under investigatoin with modification to a hand powered ratchet cutter. Preparation of the 90deg faces of the tube needs to be excellent. 6