Disclosed is an apparatus for sealing and severing a subsea pipe adapted to convey fluids, e.g., hydrocarbons, and systems and methods using such apparatus. The apparatus includes a housing adapted to attach to the pipe, a piercing tool for providing an opening in the pipe at a predetermined location and a mechanism for establishing fluid communication between a source of sealant material and space within the pipe adjacent the opening in the pipe, and a cutting mechanism for cutting the pipe. Methods disclosed include piercing the pipe to form an opening, injecting sealant material through the opening into the pipe to form a fluid-tight seal, and cutting the pipe through the seal to form sealed cut ends.