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弯头的分类方法，按它的曲率半径来分，可分为长半径弯头和短半径弯头。长半径弯头指它的曲率半径等于1.5倍的管子外径，即R＝1.5D。短半径弯头指它的曲率半径等于管子外径，即R＝D。式中的D为弯头直径，R为曲率半径。若按压力等级来分，大约有十七种，和美国的管子标准是相同的，有：Sch5s、Sch10s、Sch10、Sch20、Sch30、Sch40s、STD、Sch40、Sch60、Sch80s、XS；Sch80、Sch100、Sch120、Sch140、Sch160、XXS，其中最常用的是STD和XS两种。按弯头的角度分，有45o弯头，有90o弯头和180o弯头。这样一来弯头的种类是很多的，定货时定单常采取如下表示方法：如"LR STD 90o 8"，表示长半径，压力等级为STD，90o的8"弯头；又如，"SR XS 45o 4"表示短半径，压力等级为XS，45o的4"弯头。以上为弯头的大概分类情况。 弯管分冷弯和热弯，冷弯是现场用弯管机弯的，最小曲率半径根据管道口径确定，从18D到30D；热弯曲率半径不小于4D。弯管标准执行SY5257-2004，两端各带一定长度的直管。实际上弯头是和弯管不同的另一种零件，埋地管道基本没有用弯头的，弯头曲率半径从1D到3D，采用涨管工艺，两边不带直管。国内弯头标准执行GB12459-2005。
Elbow's classification, according to minutes of its radius of curvature, can be divided into long-radius elbows and short radius elbows. Long radius bend that it is equal to 1.5 times the radius of curvature of the pipe diameter, that is, R = 1.5D. Short radius bend radius of curvature that is equal to its diameter pipe, that is R = D. Type of D for the elbow diameter, R is the radius of curvature. If divided by the pressure level to about 17 kinds, and the U.S. standard is the same tube, with: Sch5s, Sch10s, Sch10, Sch20, Sch30, Sch40s, STD, Sch40, Sch60, Sch80s, XS; Sch80, Sch100, Sch120, Sch140, Sch160, XXS, which is the most commonly used two kinds of STD and XS. According to the angle of bend points, there is 45o bend, bend with 90o elbow and 180o. Thus many types of elbow, and orders are taken when the regular order, said method: If "LR STD 90o 8", said the long radius, pressure rating for the STD, 90o 8 "elbow; Again," SR XS 45o 4 ", said a short radius, pressure rating for the XS, 45o of the 4" elbow. Above the elbow of about classification. Cold and hot bending bending points, is the scene with cold bending machine bending, the minimum radius of curvature determined based pipeline diameter, from 18D to 30D; rate of heat bending radius of not less than 4D. Pipe standards implementation SY5257-2004, with a length to each end of the straight tube. And bend elbow is actually different from the other parts, basically useless buried pipeline elbow, and bend radius of curvature from 1D to 3D, using expander technology, on both sides with no direct control. Implementation of the standards of domestic elbow GB12459-2005.