The role of seamless steel pipe expansion

Posted by zora li on September 20th, 2022

After the cold expansion, the diameter of the pipe and the pipe will increase by about one percent. The diameter, roundness, and diameter difference between the two pipes are greatly improved. The straightness of the pipe is also greatly improved. The length of the pipe is shortened. At 0.5%, the wall thickness is reduced by approximately 0.8%. Overall and effective overhaul of the overall function of the steel pipe. Improve the geometric accuracy of the seamless steel pipe and the pipe end, so that the diameter and roundness of the pipe and the difference between the two pipe diameters meet the standard requirements, which is convenient for on-site welding. The tension reduction process is a continuous rolling process in which the hollow base metal does not have a core rod. Under the premise of ensuring the welding quality of the mother tube, the seamless tube tension reducing process is to heat the seamless tube to 950 degrees Celsius or more, and then it is rolled into various types by a tension reducer (a total of 24 times of the stretch reducer). The finished pipe with outer diameter and wall thickness has the essential difference between the hot rolled steel pipe produced by this process and the common seamless pipe. After heating in the heating furnace, the metallographic structure and mechanical properties of the weld joint and the parent body can be completely consistent. Through multiple passes of tension reducer rolling and automatic control, the dimensional accuracy of the steel pipe is better than that of the similar seamless pipe.

The uneven deformation of the seamless pipe forming and welding process reduces the residual stress caused by the forming and welding of the pipe, improves its distribution and improves the overall mechanical performance of the steel pipe. These changes should be fully taken into account in the development of the seamless steel tube process. The width, length and thickness of the sheet material for the tube and the outside diameter of the steel tube prior to expansion should be taken into account so that the geometric dimensions of the steel tube after the diameter expansion do not reach the ultimate requirements. With different grids, the cold expansion path also has the effect of improving the straightness of the seamless pipe, especially the straighter action of the smaller diameter seamless steel pipe is more pronounced.

Read more: seamless carbon steel pipe

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zora li

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zora li
Joined: August 16th, 2022
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