A tool for tightening and loosening a pipe fitting, comprising a cup-shaped tool head having an opening for receiving a pipe and a shaft attached to and extending from the tool head. The tool head has an interior surface adapted for a pipe fitting such that the pipe fitting may rotate with respect to the tool head. The shaft is shaped to receive a pneumatic hammer. The pneumatic hammer has a hammer head, and the hammer head in operation extends into the interior of the tool head to act on a wing of the pipe fitting.