In piping systems, elbows are fittings used to change the direction of the pipeline. Commonly available in 45°, 90°, and 180° angles, additional non-standard angles like 60° are also available based on engineering requirements. Elbow materials include cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals, and plastics.

Connection methods to pipes include: direct welding (commonly used), flange connection, hot melt connection, electric melt connection, threaded connection, and socket connection, etc. Categorically by production process, they are: welded elbows, stamping elbows, push-formed elbows, casting elbows, and double-welded elbows, etc. Other names: 90-degree elbows, right-angle elbows, etc.