What are the methods for expanding the outer diameter of the 20#oil-cracking steel pipe

What are the methods for expanding the outer diameter of the 20# oil-cracking steel pipe? What are the advantages? With the development of industrial technology and the petroleum and chemical industries, the demand for large-diameter seamless steel pipes has increased year by year. Although large-scale cyclic pipe rolling units and pipe jacking units can produce some large-diameter 20# oil cracking steel pipes, their equipment is huge, the one-time investment is high, and there are certain technical difficulties in producing large-diameter thin-walled pipes. There are mainly the following methods for hot expansion of pipes:

(1) The oblique rolling hot expansion of 20# oil cracking steel pipe is carried out on an oblique rolling expansion machine. The oblique rolling expansion machine has two cantilevered conical rollers installed in a box-shaped frame. The characteristics of the oblique rolling expansion of 20# oil cracking steel pipe are large deformation, fast deformation speed, and high output. It is suitable for producing large-diameter and medium-thin-wall 20# oil cracking steel pipes of various steel grades with high dimensional accuracy, but its disadvantages are that the unit equipment is huge, the investment is high, and it cannot produce special-shaped and variable-section seamless pipes.

(2) The hot expansion of 20# petroleum cracking steel pipe is carried out on a hot-drawing expansion machine. The characteristics are that the expansion machine can both hot expand and hot draw, and can not only hot expand round pipes, but also pull special-shaped and variable-section pipes; the equipment of the drawing and expanding machine is light, the investment is small, and the tool replacement is simple; but because the drawing and expanding is free deformation, the surface defects of the 20# petroleum cracking steel pipe expanded products are easy to expose and expand, and the wall thickness accuracy and outer diameter accuracy are not high.

(3)In recent years, a new medium-frequency induction heating hydraulic two-step push-type anti-inflammatory expansion process has emerged, which is different from the traditional drawing and expanding process. It is used to produce large-diameter 20# petroleum cracking steel pipes. The process equipment is simple, and each unit has tens of tons. Moreover, the expanded 20# petroleum cracking steel pipes are mostly uniform in structure, with finer grains and good mechanical properties. Therefore, it has become the most popular large-diameter 20# petroleum cracking steel pipe production process.