Abstract: This invention relates to a self-actuating safety valve arrangement, and includes a main valve housing having an inlet and an outlet for connection in a high pressure fluid line. A valve member is carried slidably within the main valve housing and is movable from an open position, in which it allows the passage of fluid through the fluid line, to a closed position. An auxiliary inlet port is formed in the housing and communicates with one end of a feedback line. The opposite end of the feedback communicates with an outlet port of a pilot valve, which is actuated by means of an orifice plate located in the fluid line downstream of the valve member. A lowering in pressure in the fluid line, generally caused by a downstream rupture or breakage, causes the orifice plate to close the pilot valve, which results in a drop in pressure in the feedback pipe. The main valve member is arranged to move to the closed position in response to the drop in pressure it experiences via the feedback pipe.