A method for opening a port through the wall of a ported sub including: providing a sub with a port through its tubular side wall; providing a hydraulically actuable valve to cover the port, the valve being actuable to move away from a position covering the port to thereby open the port; increasing pressure within the sub to create a pressure differential across the valve to move the valve toward the low pressure side, while the port remains closed by the valve; thereafter, reducing pressure within the sub to reduce the pressure differential; and driving the valve to move it away from a position covering the port.

A method for opening a port through the wall of a ported sub including: providing a sub with a port through its tubular side wall; providing a hydraulically actuable valve to cover the port, the valve being actuable to move away from a position covering the port to thereby open the port; increasing pressure within the sub to create a pressure differential across the valve to move the valve toward the low pressure side, while the port remains closed by the valve; thereafter, reducing pressure within the sub to reduce the pressure differential; and driving the valve to move it away from a position covering the port.

The present invention relates to a safety valve (1) having a valve housing (2), in the housing interior of which there is provided a shut-off body (3) which is held in an open position of the safety valve (1) by at least one elastic retention element (4) counter to the force of a medium flowing through the valve housing (2), in which open position the medium flows through a valve opening (5) in the shut-off body (3). Here, the shut-off body (3) is displaceable in the valve housing (2) such that the shut-off body (3), in the event of a pressure drop on its outflow side, moves against a closing body (7) into a closed position of the safety valve (1) in which the closing body (7), which is acted on by at least one resilient pressing element (8), sealingly closes off the valve opening (5) in the shut-off body (3), wherein at least one bypass duct is provided which, in the closed position of the safety valve (1), can be opened to connect the inflow side of the shut-off body (3) to the outflow side thereof until the shut-off body (3), when the pressure has been equalized by the at least one bypass duct, is moved into the open position of the safety valve (1).

A method for opening a port through the wall of a ported sub includes providing a sub with a port through its tubular side wall and providing a hydraulically actuable valve to cover the port. The valve can be actuable to move away from a position covering the port to thereby open the port. The method also includes increasing pressure within the sub to create a pressure differential across the valve to move the valve toward the low pressure side, while the port remains closed by the valve, and thereafter, reducing pressure within the sub to reduce the pressure differential to move valve away from a position covering the port.