Expanding and blocking preventing device used for radial hole forming of pipeline and expanding and blocking preventing method

The invention discloses an expanding and blocking preventing device used for radial hole forming of a pipeline, and belongs to the technical field of oil and gas storage and transportation safe operation. The expanding and blocking preventing device comprises parallel reinforcing ribs, a parallel double-arch rib plate, an inclined rib plate and a center positioning plate, and is characterized in that the parallel reinforcing ribs are composed of two parallel edges; the center positioning plate is round inside and square outside; the two ends of the center positioning plate and the two edges of the parallel reinforcing ribs are fixed; the parallel double-arch rib plate comprises two side faces of the same structure; the lower portions of the side faces are each of an arch-shaped structure; the radian of each arch-shaped structure is consistent with the radian of the outer diameter of the pipeline where a hole is about to be formed; the upper portions of the two side faces and the two edges of the parallel reinforcing ribs are fixed respectively; and the lower plane of the center positioning plate is tangent to the arc tops of the arch-shaped structures. The expanding and blocking preventing device is used in radial hole forming operation of the oil and gas pipeline under pressure; due to the fact that the expanding and blocking preventing device is pre-welded before hole forming, the problem that a saddle-shaped arc plate is deformed because of internal stress release in the hole forming cutting and separating process, and consequently a cylindrical cutter is expanded and blocked is solved; and the hole forming success rate is increased.