Metallurgical investigation of leakage observed in welded interface of Pilot pressure distributor of liquid stage for aerospace application

•Pilot Pressure Distributor (PPD) system is used in the liquid fuel stage of launch vehicles for pressurizing the flow of liquid propellant.•Austenitic stainless steels are used for the fabrication of PPD, adapter and plumbing lines of liquid fuel stage of launch vehicles and the plumbing lines and adapter were welded together using SS308L filler wire with 3 mm fillet size.•The distributor was hydro tested at 120 bar pressure and integrated with engine. During leak test at 60 bar with snoop solution, a frothing leak was observed at PPD distributor weldment. The component was disassembled from the system and subjected to metallurgical analysis to identify the root cause of leakage.•A detailed metallurgical analysis was carried out on the leaked PPD rod using different characterization techniques and the analysis revealed leakage in PPD distributor attributed to the lack of fusion in the weld joint. Pilot Pressure Distributor (PPD) system is used in liquid fuel stage of launch vehicles for the pressurized flow of liquid propellant. The PPD system is fabricated out of AISI304L austenitic stainless steel. The system consisted of adaptor and plumbing lines is welded together using Gas Tungsten arc welding technique. The distributor system is subjected to hydro test at 120 bar pressure and then post- harnessing command line leak check is carried out after the hydro test. During the leak test at 60 bar with snoop solution, a frothing leak is observed at PPD distributor weld joint. A pressure drop of 6 bar was also observed over a duration of 10 min. The leaked PPD distributor was dismantled from the assembly and subjected to detailed metallurgical investigation to identify the root cause of leakage. The metallographic analysis revealed leakage in PPD distributor attributed to the lack of fusion in the weld joint.