Main Reasons Those Affect The Quality of Pipe Bend

There are some factors that will affect the quality of bend when DMH is manufacturing bend. How to solve these problems? Ranibow-steel, a senior carbon steel pipe supplier, will share with you.

1. The tensile stress of the tube under the action of external force m under the action of the outer layer of the side wall & 1 thinning action, i.e. the lateral compression stress. Under the action of thickening, N1 and N2 together make the cross section of the pipeline change. Based on this factor, the main reason of elbow quality decline is RX and SX. Therefore, gbj235-82 defines various pressure levels under RX value and lateral thinning, so as to control RX with SX value and ensure quality.


2. The bending accuracy of the bend is also one of the factors affecting the quality. When we manufacture the bending foot, in addition to controlling a certain range of tolerance on the specification size, we also require the user to select the corresponding bending tire according to the bending diameter used.



3. The bending performance and surface corrosion of the pipe itself may also affect the quality of the elbow. In the field construction, operators also need to know the processing, processing performance and surface corrosion of pipeline materials to make judgments.



4. When the material is stretched out, the inner compression and elbow mode of the neutral axis are different from that of the top bending (compression bending), the neutral axis is about 1 / 3 of the outer wall, and when the material is rotated bending (backward bending), the neutral axis is 2 / 3 of the outer wall. Therefore, when the thin-walled tube is bent, the rotation method is useful.


5. According to the acceptance pipe processing specification: cold bending steel pipe, low pressure is 4D, high pressure is 5D.