OMP: Major maintenance policy of the LHC Accelerator and Detectors Motors & Compressor for the EYETS, YETS & LS2 period.

Maintenance strategy Applied maintenance method: Condition based maintenance with periodically vibration analysis as main monitoring tool. PM (Maintenance Plan) Spare part strategy System relevant compressor must have an equivalent compressor as cold or hot spare. (List in appendix)

Preventive maintenance After LS1 four cases of performed preventive maintenance November 2014 - Major overhaul QCCV-AERH07 VMY536aH compressor sent for major overhauling caused by noted increased vibration. Aerzen analysed wrong axial bearing load. June 2015 - Bearing change QCCV-AERH08 Increasing of the bearing frequencies noted within one month. Aerzen analysed non conformity at bearing mounting November 2015 - Bearing change QCCV-AERB15 Increasing of the bearing frequencies over several months. Decision was taken based on strategy (one spare for two bearing issues). SKF analysed that bearing issue was caused by a large number of overrolled indentations caused by soft and large, but also hard micro-particles. October 2016 – Bearing change QCCV-AERB15 Increasing of the bearing frequencies over several month. Decision was taken after putting pressure to SercAL and their vibration expert to take position taking into account the increased vibration behavior.

Corrective Maintenance Since the LHC- restart, one case of corrective maintenance ANRS Kaeser FSB440 compressor break down on 26/09/2016 . A Lack of vibration expertise's and communication has led to a corrective maintenance task. Nous relevons sur les mesures de la vis femelle du côté accouplé (DS) la présence des pics à une fréquence de 5,2 ordres. Cette fréquence est caractéristique d'un défaut de piste externe du roulement FAG NU316E. Cette fréquence était déjà visible lors de la mesure du 6 septembre (I-care counter expertise from 06/10/2016) In addition to the standard exchange (2 wks), a complete (time consuming) cleaning of the complete oil circuit was performed. (CPMD 10th October 2016) ATLAS Liquid argon Cryogenics: low availability (58%) of the dedicated nitrogen plant due to compressor breakdowns; 100% availability of the detector due to liquid nitrogen supply (Plenary Meeting 2016 - Thursday 24th of November 2016)

Summary Since it has been decided that vibration expertise shall be part of S176 contract, CRG/ME has reported several non-conformities (Vibration analyses, measurement and communication) to CRG/ML. => Strategy of predictive maintenance is questionable; => CRG/ME can no longer support efficiently the maintenance strategy.

Actually Communication flow shows a lack of efficiency Sub-contractor Expert CRG-ME CRG Operation Communication flow until 30 June 2016 CRG-ME CRG-ML CRG Operation Sub-contractor Expert Advanced Vibration Analysis Not defined Advanced Vibration Analysis

Many thanks for your attention

Compressors with more than 34’000 running hours at the end of 2017 (YETS)

Compressor List Detector

Compressor List LHCA Air Liquide / Linde

LHCB

LHCC Air Liquide - Linde

LHC cryogenic warm compressors layout LPb MPb HPb LPa MPa HPa S1-2 P18 S2-3 P2 S3-4 S4-5 P4 S5-6 S6-7 P6 S7-8 S8-1 P8 Aerzen Stal LHC cryogenic warm compressors layout 9 types of compressors: 2 Aerzen types (536aM & 536aH) - 7 Stal types (S73_LP, S73_HP, S75, S87, S89, S93_LP & S93_HP) 8 cryo plants 5 cryo islands Available spares (2016) (HP/ LP) (HP/ LP)

ATLAS & CMS “Hot spare” solution Upgrade of ATLAS and CMS compressor stations during first long shutdown (LS1) period of LHC (2013-2014) ATLAS : exchange of C2 compressor to ensure a mininimum of 400 g/s with three boosters, and new C6 compressor CMS: new hot spare compressors