## 2 Literature Background
They also investigate the impact of manpower management strategies, such as training and staffing, on maintenance effectiveness, along with exploring different approaches to control and optimize maintenance productivity, such as process improvement, performance metrics, and resource allocation. In [PERSON] et al. [14], multiple flow-control valve-stem packing failures in an LNG plant are investigated. Through a root cause analysis (RCA), they analyzed historical failures' data series and maintenance records. The work of [PERSON] and [PERSON] [15] presents a reliability analysis of the emergency switching system of an LNG plant comparing the existing configuration and the proposed new configuration. The analysis uses software modeling based on a fault-tree diagram. The proposed design concept improves the reliability of the emergency system by reducing unavailability. [PERSON] et al. [14] present a case study where the failure of the primary seals of the swing joint (SW) of the loading arms is studied. The incident of loading-arm primary seals deformation is critically evaluated using the RCA to identify the failure and determine the maintenance needs for the LNG ship-to-ship loading reliability improvement procedure. The main conclusion of that work, based on a cost analysis of the seal failure replacement with dual redundancy, is a modification in the facility design. In the paper by [PERSON] et al. [17], the functions, causes, and effects are pinpointed, and the updated maintenance tasks are defined. In the same line, and aiming at the efficiency of maintenance operations, the paper seeks to identify the most influential factors that impact the Wrench Time (WT) of labor productivity, identifying causes to achieve a clear vision of how management can allocate the necessary resources to eliminate such impacts. Random sampling of field observations was used for this purpose. For data collection, the Day in Life Of (DILO) approach was used as an observation method involving the supervisor's participation with the technicians throughout the workday. To validate the methodology, a case study was conducted based on one of the largest LNG plants in the Middle East. Risk analysis is also an important aspect in the operation of LNG plants [19]. Despite this, the body of work on risk-analysis model classifications for LNG facilities is notably sparse [19]. [PERSON] and [PERSON] [21] conducted a systematic review of the current state of the literature on LNG risk analysis with the aim of mapping the risk analysis of LNG installations. The major contribution of this work aims to help regulators, policy makers and LNG facility operators to Identify the risk analysis models that align with their specific needs. [PERSON] et al. [22] propose a decision model to select a set of risk-based maintenance actions in gas pipelines. The model focuses on sustainability aspects, oriented towards the Triple Bottom Line approach (environmental, economic, and human). Additionally, the model integrates the multicriteria PROMETHEE method to select the maintenance actions. [PERSON] et al. [23] also use a multicriteria method (AHP) to aid in defining the best maintenance strategy. Furthermore, as a way to reduce the effects of subjectivity in the aforementioned method, it is complemented with the execution of Monte Carlo experiments. Finally, the feasibility of the proposed framework was assessed by examining a well-control system in an actual oilfield [24]. The article by [PERSON], et al. [25] proposes a methodology to evaluate the gas supply reliability of natural gas transmission pipeline systems. Using Monte Carlo experiments, an indicator quantifying gas supply reliability is obtained. Finally, in a case study focused on an actual gas transmission pipeline system, the average gas supply reliability is obtained. In addition, the effects of uncertainties in supply capacity and market demand on gas supply reliability are examined. In addition, recommendations for enhancing gas supply dependability are put forward.