Tee 2 : A pressure containing fitting with three openings. Two openings opposite one another to form the run portion of the tee, and one opening at 90o to the line of the run. Tees may be threaded, flanged, or studded-flange. (Spec 6A)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}