Complex sentence: A 90 degree elbow, also called "90 bends or 90 ells", is a fitting device which is bent in such a way to produce 90 degree change in the direction of flow of the content in the pipe.
Split into simpler sentences: A 90 degree elbow is also called "90 bends or 90 ells". It is a fitting device which is bent in such a way to produce 90 degree change in the direction of flow of the content in the pipe.