FOTO 24/11/2011 PS FWS RELIABILITY 1 IMPROVING THE PS FWS RELIABILITY

PS fast wire scanner: why the instrument reliability has become an issue 24/11/2011 PS FWS RELIABILITY 2 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

Reliability problems 24/11/2011 PS FWS RELIABILITY 3 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

Analysis of the problem 24/11/2011 PS FWS RELIABILITY 4 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 X y1

24/11/2011 PS FWS RELIABILITY 5 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

24/11/2011 PS FWS RELIABILITY 6 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 Solution to the problem

Validation test 24/11/2011 PS FWS RELIABILITY 7 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

Conclusions 24/11/2011 PS FWS RELIABILITY 8 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

Other shutdown activities 24/11/2011 PS FWS RELIABILITY 9 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

Acknowledgemets 24/11/2011 PS FWS RELIABILITY 10 I would like to thank all the people who helped for these studies and in particular R. Sautier, D. Gerard, M. Hamani, F. Camba, S. Leblanc, J. Emery, A. Guerrero and R. Veness A special thanks to Jurgen Enzinger from Comvat for his willingness to quickly find a new bellows for our application A big thanks also to EN-MME-AF section and to air liquide for their prompt reaction to have our instrument ready within a very short delay