Improvements to high pressure fuel fittings

A fitting for making a metal-to-metal fluid seal, the fitting comprising:

• a first conduit defining a first fluid passage, the first conduit having a generally spherical-shaped exterior surface at a first end thereof;
• a second conduit defining a second fluid passage, the second conduit having a generally conical-shaped interior surface for receiving the generally spherical-shaped exterior surface of the first conduit, wherein the second conduit includes a threaded exterior surface;
• a nut engaged with the threaded exterior surface of the second conduit, tightening of the nut on the threaded exterior surface urging the first and second conduits axially together to apply increasing pressure between the generally spherical-shaped exterior surface and the generally conical-shaped interior surface;
• and
• a ring positioned between the first conduit and the nut, the ring having a radially facing outer surface that is radially spaced a distance from a radially facing inner surface of the nut,
• wherein the ring has a groove open to the outside of the fitting to provide a dedicated leak path for fluid inside the fitting but outside the first and second fluid passages to escape from the fitting at a predetermined location.