In piping systems, elbows are fittings used to change the direction of the pipeline. By angle, there are three commonly used types: 45°, 90°, and 180°, as well as other non-standard angles like 60° according to engineering requirements. Elbows are available in materials such as cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals, and plastics.

Ways to connect pipes include direct welding (the most common method), flange connection, hot melt connection, electric melt connection, threaded connection, and sleeve connection, etc. They can be categorized by production process into: welded elbows, stamped elbows, mandrel elbows, cast elbows, and socket weld elbows, etc. Other names: 90-degree elbows, right-angle bends, etc.