Abstract: A leak detection apparatus for pipe couplings includes a sleeve for enclosing a small volume on the exterior of a pipe joint with a flow passage on the sleeve for communication with a detection instrument; the sleeve may be a stiff but deformable polyurethane tube having separable edges including reinforcing strips embedded in the sleeve adjacent the edges; the sleeve may also be a fluid impervious fabric web that is, in use, wrapped about a pipe joint. The detection method includes a delay time after the pipe coupling is pressurized. It is also possible to release the pressure prior to sampling, as for example due to safety considerations. The leak detection apparatus includes means for conversion of leaked gas concentration to leak rate.