Rupture discs are manufactured with a thin dome whose profile and thickness determine the burst pressure. When the differential pressure between its two faces reaches the design value, the material deforms plastically and opens (forward-acting) or the dome first reverses and then tears along calibrated scores (reverse-acting).
After bursting, a full opening is created —often petal-shaped— that discharges the fluid with almost no additional pressure loss. Since it has no mechanical parts that return to their original position, the disc must be replaced after each activation, but it offers a much faster response than traditional pressure relief valves.
Full guide: What is a rupture disc: definition, operation and uses