A pipe-born BOP cleaning tool comprising - a first pipe section with upper and lower threaded box and pin thread connections to pipe sections above and below, - said pipe section provided with a through central channel and inner radial channels in distinct levels to a distribution annulus within an external tubular member with external fins, - said tubular member having and outer radial channels from said distribution annulus to nozzles between said fins for flushing fluid from said central channel out into a BOP bore for washing cavities in said said BOP bore, - said central channel provided with a flow control sleeve provided with holes, - said flow control sleeve displaceable from a radially closed initial first closed position to a second position with said holes aligned with said inner radial channels for starting flushing through said nozzles, and further displaceable to a radially closed third position with said holes out of alignment with said inner radial channels for halting said flushing through said nozzles, - said flow control sleeve displaceable from said first, initial position by a first dart dropped into said first pipe section and stopping in a first seat in said flow control sleeve below said holes, thereby closing said central channel, building pressure in said central channel, displacing said flow control sleeve to said second position and redirecting pipe flow to said nozzles, characterized in that - said flow control sleeve is displaceable from said second position to said third, closed position by a second dart dropped into said first pipe section and stopping at said first dart, said second dart blocking said holes thereby building pressure in said first pipe section, further displacing said flow control sleeve to said third position triggering a release mechanism for said first seat to release said first dart and said second dart. - a first pipe section with upper and lower threaded box and pin thread connections to pipe sections above and below, - said pipe section provided with a through central channel and inner radial channels in distinct levels to a distribution annulus within an external tubular member with external fins, - said tubular member having and outer radial channels from said distribution annulus to nozzles between said fins for flushing fluid from said central channel out into a BOP bore for washing cavities in said said BOP bore, - said central channel provided with a flow control sleeve provided with holes, - said flow control sleeve displaceable from a radially closed initial first closed position to a second position with said holes aligned with said inner radial channels for starting flushing through said nozzles, and further displaceable to a radially closed third position with said holes out of alignment with said inner radial channels for halting said flushing through said nozzles, - said flow control sleeve displaceable from said first, initial position by a first dart dropped into said first pipe section and stopping in a first seat in said flow control sleeve below said holes, thereby closing said central channel, building pressure in said central channel, displacing said flow control sleeve to said second position and redirecting pipe flow to said nozzles, - said flow control sleeve is displaceable from said second position to said third, closed position by a second dart dropped into said first pipe section and stopping at said first dart, said second dart blocking said holes thereby building pressure in said first pipe section, further displacing said flow control sleeve to said third position triggering a release mechanism for said first seat to release said first dart and said second dart.