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 with 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.

Connection methods to pipes include: direct welding (commonly used), flange connection, hot melt connection, electric fusion connection, threaded connection, and socket connection, etc. According to the production process, they can be categorized as: welded elbows, stamping elbows, push-fit elbows, casting elbows, and double-welded elbows, etc. Other names: 90-degree elbows, right-angle elbows, etc.