The present invention relates in general to a pressure discharge mechanism for closed vessels having an internal chamber designed to hold volatile and/or explosive substances in a sealed manner comprised of an at least one eutectic composition and a threaded joint designed to open or vent the closed vessel when the contents of the closed vessel reaches a predetermined temperature while maintaining full structural integrity during normal operation. In one aspect, the closed vessel is a munitions casing which functions as intended under normal operating environments, but then when exposed to extreme temperatures, reduces the munition's high order explosion capability, and is transformed into a safe, low order reaction with significantly less reactive potential. In one aspect, the closed vessel is a transport tanker which should not release substances contained therein. However, if the tanker catches fire, the pressure relief mechanism of the present invention reduces risk of explosion.