Rupture disc (bursting disc)

ISO 10628-2 (group 23, safety valves and fittings) / PIP PIC001 / API 520 / ISO 4126-2

Drawn as

Two short parallel bars (the holder) across a vertical pipe, with a curved arc between them bulging towards the outlet.

Meaning

Non-reclosing relief device that bursts at a set pressure. Used alone, or under a PSV to protect it from corrosion (then a pressure gauge or PI is drawn between them). ISA tag is PSE. Becomes rupture-disc.

Variants

Some legends draw a vertical pipe with a dashed or zig-zag line across it
Buckling-pin relief valves are drawn as a body with a pin and tagged PSE too