The decline in the condition of a gas turbine system for transporting natural gas is investigated. The degradation coefficient is obtained by analysis of data from the system’s measuring equipment. It is important to determine the condition of equipment on the basis of its operational parameters, since that would abbreviate thermal testing and permit maintenance and repair of the equipment on the basis of its condition rather than on a fixed schedule. Besides assessing the condition of the equipment, the proposed algorithm permits the identification of anomalies in the initial and final data. Expert analysis reveals anomalous zones in the downward trend of the gas turbine system’s condition over time. © 2023, Allerton Press, Inc.