Investigation of Leakage Observed in AISI 321 Stainless Steel Separation Pyro Valve During Post-Function Acceptance Test.

Autor: Manwatkar, Sushant K., Jalaja, K., Gupta, Rohit Kumar, Padmanabhan, Rishi, George, Philip, Anoop, P., Murty, S. V. S. Narayana, Mohan, M.
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Zdroj: Journal of Failure Analysis & Prevention; Aug2023, Vol. 23 Issue 4, p1789-1802, 14p
Abstrakt: Cryogenic engine of satellite launch vehicle employs separation pyrovalves which are pyrotechnically actuated devices used for opening/closing of the flow of fluids. In the qualification test, pyrovalve withstood the functional test. However, during the post-fire acceptance test, one unit of the separation pyrovalve indicated leakage at 38 bar against specified 170 bar pressure. The leaked actuator diaphragm was investigated for identifying the reason for leakage. Leakage during post-fire acceptance test is attributed to the through-thickness hole formation on the AISI 321 stainless-steel diaphragm. Hole formation in diaphragm is caused by the impingement of molten zirconia from the combustion products of zirconium/potassium perchlorate (ZPP) charge to the diaphragm during firing operation. It was responsible for localized melting of stainless steel. After the formation of through-thickness hole on the diaphragm, the molten mixture got solidified and filled the through hole completely. During the post-fire acceptance test, the molten and solidified mixture got dislodged at 38 bar pneumatic pressure and resulted in leakage. Analysis is validated through thermal modelling and simulation, where observations are found to be matching. Estimation of combustion product required for the formation of through thickness hole of the observed dimension has also been estimated. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index