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