U type bending process is divided into 2 steps: the first mechanical polishing, the main purpose is to end pipe repair, rough polishing, and electrochemical polishing, this is a surface treatment of stainless steel products, the most advanced technology, through the control of chemical reaction occurred in the surface of stainless steel products in the electrolyte, and ion transfer in order to make the product surface tends to be flat state. Two times the product through the mirror finish, Ra is less than or equal to 0.28 m, at the end of the tube and the outer wall of the pipe fitting of light.

Can replace the elbow elbow in some cases, but the pipe wall thickness should not be less than the pipe wall thickness, the elbow is standard parts can be directly used, elbow is standard. Some places will use pipe, such as conveying solid particles in the material, need to bend large bending radius, bend to reduce material erosion for elbow is a standard part, only R=1.0D and R=1.5D specifications, in order to ensure the pipe bent elbow after elbow R minimum wall thickness, to 3D. The elbow is also widely used in chemical fertilizer high pressure pipelines, and sometimes large R bends are required to meet the requirements of flexibility in the heat pipe.