PT. X is one of the upstream oil and gas industry assets in Indonesia that produces natural gas and petroleum from production wells in Natuna Sea, with natural gas production capacity of 165 MMSCFD and 2000 BPD oil. The natural gas exported through a subsea pipeline to Singapore under a 30 years Gas Sales Agreement (GSA) contract. The issue of managing, planning and execution of facility maintenance activities is important to achieve high efficiency and performance. This study is intended to improve lean manufacturing of Turn Around Maintenance (TAM) with Value Stream Mapping and Operational mode methods. The current state mapping in flare tip inspection activities, can increased its Value Added Time (VAT) from 67% to 81% and increase the effect of Lead Time to 63% in the future state map. Research on operational modes using the PLS- SEM method with SmartPLS software provides results on the relationship between the influence of planning and improving lean manufacturing on operating performance. The result showed that there was a positive and significant influence of the scope of TAM, contractor's competency on TAM performance. It is also resulted in a positive and significant influence of TAM performance and maintenance performance on the operating performance of the AG platform. Meanwhile, the business planning process does not have a significant effect on TAM performance.

Keywords : Lean Manufacturing, Turn Around Maintenance, Value Stream Mapping, PLS