Typically , Rupture Disc Applications fall into one of the following categories Primary Relief: Where a Pressure Relief device is Used as the Primary or Sole Relieving device, a rupture disc may be used as the only means of over-presssure protection. Secondary Relief: The Rupture disc devices may be used to Provide secondary relief to other rupture discs or Pressure relief valves. Combination: The rupture disc device is Located between a pressure relief valve and the Process thus preventing leakage or weeping through the pressure relief valve.