According to production processes, they can be categorized into: welded elbows, stamped elbows, cast elbows, etc.

Divided by material: carbon steel, cast steel, alloy steel, stainless steel (304, 316, 310, 321, 301), copper, aluminum alloys, etc. (However, the small wooden factories all use pure forgings.)

Manufacturing methods include: extrusion, forging, stamping, casting, etc. (Nowadays, it's mostly pure forging.)

304 stainless steel elbows can be further categorized into equal-diameter elbows and unequal-diameter elbows. Equal-diameter elbows are used to connect pipes with the same outer diameter, while unequal-diameter elbows are used to connect pipes with different outer diameters.

Manufacturing standards include: National Standard, Electrical Standard, Water Standard, American Standard, German Standard, Japanese Standard, etc.

Curvature Radius Classification: They can be divided into long-radius elbows and short-radius elbows. Long-radius elbows refer to elbows where the curvature radius is 1.5 times the pipe's outer diameter, i.e., R = 1.5D. Short-radius elbows refer to elbows where the curvature radius is equal to the pipe's outer diameter, i.e., R = 1.0D. (D is the elbow diameter, R is the curvature radius.)

By pressure class, there are approximately seventeen types, which are the same as the American pipe standards, including: Sch5s, Sch10s, Sch10, Sch20, Sch30, Sch40s, STD, Sch40, Sch60, Sch80s, XS; Sch80, SCH100, Sch120, Sch140, Sch160, XXS; among which, STD and XS are commonly used.