Piping Elbow and Piping bend are not the same, even though sometimes these two terms are interchangeably used.
Butt weld pipe Tee allows a 90 degree branch off from a running pipe.
Long Radius Pipe Bends & Return Dimensions (Pipe U Bends)
Wrought Pipe Fitting dimensions are always in line with connecting pipe dimensions.
Pipe Fittings are Piping component that helps in Changes the direction of the flow such as elbows, tees.
A buttweld fitting is a weldable pipe fitting that allows for change of direction of flow, to branch off, reduce pipe size or attach auxiliary equipment.
Butt weld fittings get their name from the method for which they attached to a piping system.
ELBOWS, 90 DEG. SHORT RADIUS, ALLOY STEEL 1-1/4% CR. +1/2% MO., BUTT-WELDING, SEAMLESS MAT. IN ACC. WITH ASTM-A234 GRADE WP11 DIMENSIONS
ASTM A420/A420M-07 Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service.
ASME B16.9 Standard covers overall dimensions, tolerances,ratings, testing, and markings for factory-made wrought buttwelding fittings in sizes NPS 1⁄2 through NPS 48 (DN 15 through DN 1200).