Abstract: A pipe-clamping tool (100) comprises a tool body (102) and first and second tool jaws (104, 106). The tool further comprises a bar (110) in threaded engagement with a portion of the tool body. One end of the bar engages with a boss (108) on a side of the first tool jaw opposite the curved surface thereof. The tool jaws may be closed and opened by rotation of a handwheel (112). The first tool jaw has projections (111A, 111B) which engage respective grooves (101A, 101B) on opposite sides of the tool body; together with the bar and boss, these inhibit rotation of the first tool jaw with respect to the tool body. The pipe-clamping tool may be used to stop a leak in a pipe by applying a layer of deformable material around the pipe and clamping it in place using the tool. The tool enables a substantially complete (360°) azimuthal seal around a pipe with only a single operation on the tool (i.e. rotation of the handwheel to close the tool jaws). The tool jaws remain mutually aligned as they are opened and closed.