According to its radius of curvature, it can be divided into long radius elbow and short radius elbow. 

The long radius elbow refers to the outer diameter of the pipe whose radius of curvature is equal to 1.5 times, that is, R=1.5D; 


Short radius elbow means that its radius of curvature is equal to the outer diameter of the pipe, that is, R= 1.0d. 

(D is elbow diameter, R is radius of curvature).
 

5. According to the pressure grade, there are about 17 kinds of tubes, which are the same as American standards, including Sch5s, Sch10s, Sch10, Sch20, Sch30, Sch40s, STD, Sch40, Sch60, Sch80s, XS; Sch80, SCH100, Sch120, Sch140, Sch160, XXS The two most commonly used are STD and XS.

 

6. According to different shapes and uses, it can be divided into: grooved elbow, card sleeve elbow, double socket elbow, flange elbow, reducing elbow, fixed seat elbow, internal and external tooth elbow, stamping elbow, push elbow, socket elbow, butt welding elbow, inner wire elbow, etc.