The present invention relates to a safety valve including:
a tube intended to be fixed to a watch case,
a hollow head mounted for rotation about the tube,
a first element fixedly mounted with respect to the head and
a second element integral with the head,
wherein the first element and the second element each include one or more passages allowing gas to flow, the rotational motion of the head allowing the passages of the first element and of the second element to be placed in communication for gas to escape from the interior to the exterior of the case in case of overpressure inside the case or, conversely, allowing the passages of the first element and of the second element to be moved out of alignment to prevent gas escaping.