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°, depending on engineering requirements. Elbow materials include cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals, and plastics.

Connection methods with pipes include: direct welding (commonly used), flange connection, hot melt connection, electric fusion connection, threaded connection, and socket weld connection, etc. Categorized by production process: welded elbow, pressed elbow, expansion elbow, cast elbow, and double-welded elbow, etc. Other names: 90-degree elbow, right-angle bend, etc.