In piping systems, elbows are fittings used to change the direction of the pipeline. They come in three common angles: 45°, 90°, and 180°, with additional non-standard angles like 60° available as needed for engineering purposes. 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. Production processes can be categorized as: welded elbows, forged elbows, mandrel-formed elbows, cast elbows, and socket-weld elbows, etc. Other names: 90-degree elbows, right-angle elbows, etc.