ASME pipe elbows are first categorized by their bend radius, which can be classified into long-radius and short-radius elbows. Long-radius elbows refer to those with a bend radius equal to 1.5 times the pipe's outer diameter, i.e., R = 1.5D. Short-radius elbows refer to those with a bend radius equal to the pipe's outer diameter, i.e., R = 1.0D. (D is the elbow diameter, R is the bend radius. D can also be expressed as a multiple.)

Bend materials include cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals, and plastics, etc. Connection methods with pipes include direct welding (commonly used), flange connection, hot melt connection, electric melt connection, threaded connection, and socket-and-spigot connection, etc. Due to the excellent comprehensive performance of bends, they are widely used in basic engineering such as chemicals, construction, water supply, drainage, oil, light and heavy industries, refrigeration, sanitation, plumbing, fire protection, power, aerospace, shipbuilding, etc.