In piping systems, elbows are pipe fittings used to change the direction of the pipeline. They are commonly available in 45°, 90°, and 180° angles. Additionally, elbows in other non-standard angles, such as 60°, are also available based on engineering requirements. Materials for elbows include cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals, and plastics.

Ways to connect pipes include direct welding (common method), flange connection, hot melt connection, electric melt connection, threaded connection, and socket-weld connection, etc. They can be categorized by production process into welding elbows, stamping elbows, expansion elbows, casting elbows, and socket-weld elbows, etc. Other names: 90-degree elbows, right-angle elbows, etc.