Well tool device comprising a housing having an axial through bore , where the well tool device is comprising: - a sleeve section axially displaceable relative to the housing , where the sleeve section comprises an axial through bore aligned with the axial through bore of the housing ; - a fluid flow preventing disc ; - an axial fluid passage bypassing the disc when the well tool device is in an initial state (S1), thereby allowing a fluid flow (FF1) between a first location (L1) axially above the disc and a second location (L2) axially below the disc ; where the axial fluid passage is closed when the well tool device is in an intermediate state (S2); - the fluid flow preventing disc is provided in the bore of the sleeve section in sealing engagement with the sleeve section ; - the well tool device further comprises a disc supporting device for supporting the disc in relation to the sleeve section , where the disc supporting device is releasably connected to an inside of the sleeve section by means of a releasable connection device ; - the well tool device further comprising a first actuation system for moving the sleeve section axially in relation to the housing from the initial state(S1) to an intermediate state(S2); characterized in that : the fluid flow preventing device is a fluid flow preventing frangible disc ; - the well tool device further comprises a disintegration device for disintegration of the frangible disc , where the well tool device is in a final state (S3) when the frangible disc has been disintegrated by means of the disintegration device ; - the well tool device comprises a second actuating system for releasing the releasable connection device , thereby causing a release of the disc supporting device from the sleeve section . - a sleeve section axially displaceable relative to the housing , where the sleeve section comprises an axial through bore aligned with the axial through bore of the housing ; - a fluid flow preventing disc ; - an axial fluid passage bypassing the disc when the well tool device is in an initial state (S1), thereby allowing a fluid flow (FF1) between a first location (L1) axially above the disc and a second location (L2) axially below the disc ; where the axial fluid passage is closed when the well tool device is in an intermediate state (S2); - the fluid flow preventing disc is provided in the bore of the sleeve section in sealing engagement with the sleeve section ; - the well tool device further comprises a disc supporting device for supporting the disc in relation to the sleeve section , where the disc supporting device is releasably connected to an inside of the sleeve section by means of a releasable connection device ; - the well tool device further comprising a first actuation system for moving the sleeve section axially in relation to the housing from the initial state(S1) to an intermediate state(S2); - the well tool device further comprises a disintegration device for disintegration of the frangible disc , where the well tool device is in a final state (S3) when the frangible disc has been disintegrated by means of the disintegration device ; - the well tool device comprises a second actuating system for releasing the releasable connection device , thereby causing a release of the disc supporting device from the sleeve section . <EOS>