Metal detector for piping. The GFM metal detector is an update of the GRF model metal detector for piping, with additional features such as the integration of a magnetic separator (a magnetic grille is incorporated in front of the detector coil). It is compatible with already existing systems and horizontal, vertical or sloping vacuum and pressure conveyor pipes. The GFM metal detector incorporates a bypass or automatic ejection system and an optional prior magnetic grille system to separate very small ferromagnetic particles, with extremely easy cleaning.