The Assembly of the LHC Short Straight Sections at CERN: Work Organization, Quality Assurance and Lessons Learned

After 4 years of activity, the assembly of approximately 500 Short Straight Sections (SSS) for the LHC has come to an end at the beginning of 2007. This activity, which was initially foreseen in European industry, was in-sourced at CERN because of the insolvency of the prime contractor. While the quadrupole cold masses were produced in industry, the assembly within their cryostats was transferred to CERN and executed by an external company under a result-oriented contract. CERN procured cryostat components, set up a dedicated 2000 m2 assembly hall with all the specific assembly equipment and tooling and defined the assembly and testing procedures. The contractor took up responsibility for the delivery, on time, of assemblies according to the required quality. A dedicated CERN production and quality assurance team was constituted. A specific quality assurance plan was set up involving 2 additional contractors responsible for weld inspections on a total of about 20'000 assembly welds and the execution of about 3300 leak detection tests. This paper presents the organizational aspects of the activity and the experience gained throughout the production. The learning curves and statistics by type of non-conformities detected and general quality assurance aspects are presented and discussed. The main lessons learnt are summarized, in an attempt to draw some conclusions which could be useful in making strategic choices for the cryostat assembly in future large-scale accelerators.