Butt Weld Equal Tee Dimensions
ASME B16.9 Standard Fittings (Equal Tee Technical Data)
Dimension Guide (Equal Tee)

C (Center-to-End): Distance from the centerline of run to the face of the outlet, and from centerline of outlet to face of the run.
OD: Actual Outer Diameter of the pipe at the weld ends.
t (Thickness): Nominal wall thickness matching the pipe schedule.
* Wall Thickness (t) Not less than 87.5% of Nominal Wall Thickness
Source: ASME B16.9 Standard Specifications