Abstract: A device to provide a seal between a housing for a moving element such as a drill chain, piston or the like and the moving element. The device comprising a storage well to retain seal material, the block having an outlet connecting with an aperture in a housing enabling seal material to flow into the space between a housing and the moving element and form a seal, the device further including an inlet port enabling seal material precursor to be added into the block, and pressurising means to pressurise the seal material precursor and force it out of the aperture.