This technology establishes a classification system for gas fuel supply facilities in combined-cycle and gas turbine power plants, and calculates the failure probability of piping and auxiliary equipment by multiplying the base failure frequency, damage factors, and management system factors.
Gas fuel supply systems in power plants transport natural gas at high pressures of 2–5 MPa and temperatures around 200℃. Despite the high risk of fire and explosion in the event of a leak, maintenance has traditionally focused on major equipment like boilers, steam piping, and turbines. Applying existing API RBI codes used in oil and petrochemical plants fails to account for critical factors such as system-specific stresses at different piping locations and the frequent start-stop cycles of gas turbines.
This technology defines damage factors including stress ratio, wall thinning, external damage, mechanical fatigue, and low-cycle fatigue. The stress ratio factor is determined by comparing the stress ratio—derived from circumferential, longitudinal, and torsional shear stresses—against the yield strength at operating temperature. The low-cycle fatigue factor is calculated using cumulative start-stop counts and fracture cycles. It also accounts for external corrosion, corrosion under insulation (CUI), and chloride stress corrosion cracking based on material type. Applicable to Risk-Based Inspection (RBI) for combined-cycle and cogeneration plants, preventive maintenance for gas turbine fuel piping, and safety diagnostics for LNG terminals and hydrogen co-firing facilities, it enables efficient resource allocation by prioritizing high-risk piping sections for inspection.
This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of vulnerable node technology for the safe operation of combined-cycle power plants.
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