ADNOC LNG natural gas export facilities (five Gas turbines driving centrifugal compressors) had experienced blade parts liberation at the first row of blades because of Chlorine and Sulphur presence in air intake system. The objective is to identify all integrity risks and to implement advanced technical enhancements to restore critical gas turbines integrity.
ADNOC LNG team carried out Root Cause Analysis (RCA) study and investigation as per existing procedures. Team collected all the events and engaged turbine manufacturer to identify root cause through intensive analysis and studies. Also engaged metallurgical third part lab to identify the nature of encountered cracks and type of fractions. The investigation had the scope to identify the origination point of blade liberation studying the broken surfaces of the blades. From the metallurgical point of view, thorugh metal strucuture studies and magnifications of broken surfaces, it was seen a series of point where metal structure changed from its original composition, having a consequent drop in properties like strength. Furthermore, the broken surfaces was typical of a metal subjected to a constast stress. RCA concluded that gas turbine had suffered of Axial Compressor Blade Stress Corrosion. The major action plan to be implemented on fast track was to replace rotors with coated blades, then rest of RCA actions were applied. The implementations and enhancements are fulfilled jointly by ADNOC LNG and manufacturer successfully.
Main implementations are blade coating, upgrade of air filter elements and blades tip clearance optimization. The recommended enhancements were implemented and successfully arrested the risk of blades liberation to assure gas turbine integrity and sustainable gas export revenues. ADNOC LNG has successfully upgraded all axial compressors rotors and eliminated the risk of blades failure. Since applied enhancements, no further blades failure encountered confirming sustainable operations and integrity assurance. The same successful enhancements were also implemented at ADNOC LNG utilities gas turbines generator sets.
The aim of the abstract is to share and focus on success story of gas turbine integrity enhancements and improvements to assure gas export sustainability. Furthermore, it wants to draw reader attention to potential hidden issues that cannot be discovered during turbine operation in order to prevente major damages resulting in losing of turbine and production.