The basic difference between an elbow and an elbow is that the elbow is relatively short relative to the elbow. R = 1 to 2 times is the elbow, and the big multiple is called the elbow. In the production process, the cold bend pipe can be bent with the ready-made straight pipe bending machine, and the second-time completion does not require secondary anti-corrosion. However, the elbows should be customized by the manufacturers to do anti-corrosion and have long ordering periods.