A female fitting is disclosed comprising a tube having an end that includes an upset for receiving a male fitting, the upset having an outer circumference and an inwardly extending groove extending around the outer circumference for receiving a clamp or portion of a clamp and the upset having an end face and inner surface, the upset having an undercut between the end face and inner surface for receiving a flange of the male fitting. A male fitting comprises a tube having an end part; and a transition between the tube and the end part, the transition comprising a flange extending radially outward from the tube and a radiused corner connecting the flange to the end part.
