A mechanical tee fitting comprising: a lower housing having a first concave surface; an upper housing having a second concave surface, the upper housing coupled to the lower housing such that the first and second concave surfaces (120a, 120b) are opposed to one another to define an interior space of the fitting with a first central axis (X-X) for housing a tubular pipe segment aligned with the first central axis (X-X), the upper housing being coupled to the lower housing by a pair of fasteners disposed about the first central axis(X-X), the upper housing including a collar having an internal surface circumscribed about a second central axis (Y-Y) to define a cavity having a first end and a second end spaced from the first end, the first end being in communication with the interior space, the internal surface of the collar further defining a substantially cylindrical central portion of the cavity and a pair of recesses (132a,132b) formed about the cylindrical central portion, the collar including an annular lip circumscribing the second central axis (Y-Y) to define the second end of the cavity; and an insert having a tubular body including a proximal portion defining a stem and a distal portion defining a base, the tubular body including an inner surface circumscribing a longitudinal axis of the insert to define a fluid flow passageway extending axially through the tubular body, the base including a proximal surface and a distal surface, the distal surface defining a first annular segment for engaging the tubular pipe segment, and a second annular segment for insertion in an opening formed in the pipe segment, the first annular segment surrounding the second annular segment, the base including a pair of tabs (220a,220b) formed about the fluid flow passageway and engaged with the recesses (132a132b) of the upper housing to prevent rotation of the insert about the second central axis (Y-Y), the tabs (220a,220b) being aligned in a direction parallel to the first central axis (X-X) of the fitting for at least line point contact with the surface of the pipe segment. a lower housing having a first concave surface; an upper housing having a second concave surface, the upper housing coupled to the lower housing such that the first and second concave surfaces (120a, 120b) are opposed to one another to define an interior space of the fitting with a first central axis (X-X) for housing a tubular pipe segment aligned with the first central axis (X-X), the upper housing being coupled to the lower housing by a pair of fasteners disposed about the first central axis(X-X), the upper housing including a collar having an internal surface circumscribed about a second central axis (Y-Y) to define a cavity having a first end and a second end spaced from the first end, the first end being in communication with the interior space, the internal surface of the collar further defining a substantially cylindrical central portion of the cavity and a pair of recesses (132a,132b) formed about the cylindrical central portion, the collar including an annular lip circumscribing the second central axis (Y-Y) to define the second end of the cavity; and an insert having a tubular body including a proximal portion defining a stem and a distal portion defining a base, the tubular body including an inner surface circumscribing a longitudinal axis of the insert to define a fluid flow passageway extending axially through the tubular body, the base including a proximal surface and a distal surface, the distal surface defining a first annular segment for engaging the tubular pipe segment, and a second annular segment for insertion in an opening formed in the pipe segment, the first annular segment surrounding the second annular segment, the base including a pair of tabs (220a,220b) formed about the fluid flow passageway and engaged with the recesses (132a132b) of the upper housing to prevent rotation of the insert about the second central axis (Y-Y), the tabs (220a,220b) being aligned in a direction parallel to the first central axis (X-X) of the fitting for at least line point contact with the surface of the pipe segment.