Abstract: A two-part concave-convex rupture disc for use in a safety pressure relief device comprises one part which is perforated with lines of small holes that introduce controlled weakness in the disc and the other part which acts as a seal. When the pressure in a fluid on the convex side of the discs exceeds a predetermined limit, the discs will reverse their direction of convexity and the metal of which the perforated disc is made will tear cleanly along the lines of perforation and rupture so as to release the fluid in which the excess pressure occurred. The pressure at which the rupture occurs is determined by the choice of the size and spacing of the perforating holes, as well as the choice of the thickness, the material of which the discs are made, and the pressure used to form the discs.