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IMPROVING THE PS FWS RELIABILITY. FOTO. PS fast wire scanner: why the instrument reliability has become an issue. The fast wire scanner is a beam profile monitor 5 instruments are installed in the PS ring (SS54, SS64, SS65, SS68, SS85), 3 horizontal and 2 vertical
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IMPROVING THE PS FWS RELIABILITY FOTO PS FWS RELIABILITY
PS fast wire scanner:why the instrument reliability has become an issue • The fast wire scanner is a beam profile monitor • 5 instruments are installed in the PS ring (SS54, SS64, SS65, SS68, SS85), 3 horizontal and 2 vertical • Instruments usage increased significantly over the last few years • Bellows failure leads to the loss of vacuum, stops the PS complex and so also the physics programme in the SPS and LHC PS FWS RELIABILITY
Reliability problems • Transmission of the movement via two edge welded bellows • Bellows lifetime much shorter than was foreseen: • less than 10’000 cycles instead of 100’000 as specified on drawing • Looking for a solution to significantly improve the PS FWS reliability PS FWS RELIABILITY
Analysis of the problem • The bellows have to compensate a lateral movement(y,y1) as well as an axial stroke(x) • Problem found in the bellows design: number of convolutions too small, bellow length too short. Those bellows were designed, calculated and made at CERN at the beginning of the 80’s Y y1 X PS FWS RELIABILITY
With such a design the bellows cannot comply with what was requested: 100’000 cycles lifetime • Calculation and design have improved a lot: a very powerful software for CAD 3D design of dynamic system, and also improvements in bellows analysis PS FWS RELIABILITY
Solution to the problem • Very little space for modifications: the instrument main design cannot be modified • CERN metallurgy specialist strongly suggested to use 316L stainless steel that is the best material to resist pollution and corrosion. • Asked to two bellows manufactures a proposal for a new bellow fitting the newly calculated stroke and lateral movement with a lifetime of 100’000 cycles • Both companies offered almost identical solutions: the proposed bellow is produced with a very similar membrane to the existing one, it is longer and with more convolutions • Design modifications due to the new bellows • Ordered and received new bellows PS FWS RELIABILITY
Validation test • A FWS has been equipped with the new bellows • The instrument has been installed in its PS tank in our lab and put under vacuum. • The FWS will be used as in normal operation(same measure speed but with 1 cycle every 2 seconds) • The test is in progress • The first test will validate the bellows design, more test are foreseen to precisely define the new lifetime PS FWS RELIABILITY
Conclusions • The five PS FWS will be equipped with new bellows during the next WSD assuming the validation test is succesful • A new preventative maintenance policy will be developped to avoid instrument failure in the machine • More studies and test are planned for a general improvement of the PS FWS PS FWS RELIABILITY
Othershutdownactivities • Installation of 4 new FWS tanks in the SS 54, 64, 65 and 85 • Installation of the 2 pick up in the SS 54 and 64 PS FWS RELIABILITY
Acknowledgemets • I wouldlike to thank all the people whohelped for thesestudies and in particular R. Sautier, D. Gerard, M. Hamani, F. Camba, S. Leblanc, J. Emery, A. Guerrero and R. Veness • A specialthanks to Jurgen Enzinger fromComvat for hiswillingness to quicklyfind a new bellows for our application • A bigthanksalso to EN-MME-AF section and to 40-30 air liquide for their prompt reaction to have our instrument readywithin a very short delay PS FWS RELIABILITY