DIFFERENTIAL VALVE FOR A SUB-SEA FLEXIBLE PIPE

摘要

The invention concerns a differential relief valve for flexible sea line comprising: a valve body (1) including an upper part communicating externally through at least one upper communication passage (25) and a lower part communicating with at least one annular space of the flexible sea line through a communication conduit (7); an internal chamber (3) arranged in the valve body (1) and wherein prevails a chamber pressure (Pc); a main check valve (10) mounted in said internal chamber (3) and capable of taking up a closing position and an opening position, said main check valve (10) being urged in closing position by a spring calibrated with a predetermined calibrating force. The invention is characterised in that it further comprises a secondary check valve (27) mounted in the upper communication passage (25) and capable of taking up a closing position and an opening position, said secondary check valve (27) being urged in closing position by a small calibrated spring (35), such that the internal chamber (3) pressure is not less than the external pressure (Pe) for the closing position of said secondary check valve (27).