RJ flange ring groove sealing surface grinding repair and qualitative detection mold

Abstract

This invention relates to a grinding fixture for the sealing surface of an RJ flange annular grooves. By contouring and deforming annular grooves of different specifications, a set of grinding fixtures with reinforced structure, high machining accuracy, and stable quality was designed. The isosceles trapezoidal top of the fixture has a symmetrically increased long side width, ensuring sufficient grinding allowance during the annular groove grinding process, allowing the flange to be repaired and reused multiple times. The annular structure in the middle of the fixture not only strengthens the structural strength of the fixture but also avoids the problem of bonding on the beveled side, cleverly solving the problem of fixing and replacing the grinding material. The disc structure at the top of the fixture effectively prevents the torsion and elliptic deformation of the bottom isosceles trapezoid, giving the grinding fixture the accuracy of a standard groove ring gauge, making on-site qualitative testing a reality.

Description

Technical Field

[0001] This invention relates to the field of RJ flange ring groove manufacturing and repair, specifically to a jig for grinding, repairing and qualitative testing of the sealing surface of RJ flange ring groove. Background Technology

[0002] RJ grooved flanges are structural components frequently used in pressure vessels, valves, and piping system connections in the petroleum, chemical, nuclear power, metallurgy, and energy industries. Compared to other types, RJ grooved flanges are particularly suitable for systems with high temperatures, corrosive environments, large load fluctuations, and high sealing requirements. During use, factors such as media corrosion, erosion, improper installation, extrusion deformation, and substandard dimensional accuracy of the metal ring gasket can cause defects such as scratches, grooves, pits, edge collapse, and cracks on the sealing surface of the grooved sealing surface. Severe defects can lead to external leakage, affecting the safe and stable operation of the system.

[0003] For the aforementioned RJ flange annular groove damage, the most common and widely used method is to use a field flange machining center for boring repair. However, regarding the RJ flange annular groove pitch circle diameter, the symmetry of the two bevels relative to the pitch circle (different symmetries will lead to different sealing pressures between the octagonal gasket and the inner and outer ring sealing surfaces of the annular groove, and different sealing pressures will turn a double-sided seal into a single-sided seal, resulting in numerous extension problems), and the accuracy of the bevel angle, there are still no high-precision measuring tools that can effectively and accurately measure these parameters, let alone the precision machining of the pitch circle, bevel symmetry, and bevel angle by a field flange machining center.

[0004] According to the national chemical industry standards HG / T 20615—2009 "Steel Pipe Flanges (Class Series)" and HG / T20633—2009 "Metal Annular Gaskets for Steel Pipe Flanges (Class Series)", the surface roughness of the annular groove and the sealing surface of the annular gasket is 0.4-1.6μm, with the median value being 0.8μm. This precision cannot be achieved by on-site boring machinery and can only be achieved by grinding. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide an effective means that can theoretically improve the accuracy of the RJ flange ring groove to close to the basic value.

[0006] To address the aforementioned technical problems, this invention presents a grinding and repair fixture for the sealing surface of RJ flange annular grooves, referred to in this document as the "standard groove ring gauge." This ring gauge efficiently, accurately, and conveniently solves the problems of machining accuracy and qualitative testing of various dimensions of the annular groove in the manufacturing and repair of RJ flange annular grooves.

[0007] To accurately describe this "standard groove ring gauge," we use its diameter cross-sectional structure to describe its characteristics. The specific technical solution of this invention is as follows:

[0008] Drawing on the structural characteristics of octagonal gaskets, a set of structurally reinforced and modified annular grinding jigs were designed to correspond one-to-one with the ring number R value of the octagonal gasket for each specification of RJ flange annular groove. The basic dimensions of each jig are consistent with the basic values ​​of the national standard for RJ flanges.

[0009] The bottom of the standard groove ring gauge is an isosceles trapezoidal structure corresponding to the RJ flange ring groove of this specification. The top of the isosceles trapezoid is appropriately widened, taking the value F+2a, and the depth is appropriately increased, taking the value E+b.

[0010] The standard groove ring gauge has a ring structure in the middle, with a ring width of F+2a and a ring height of c. The inner and outer diameters of the ring are the same as the inner and outer diameters of the circle containing the apex width of the isosceles trapezoid, respectively. On the ring, there are several pairs of parallel small holes arranged in pairs along the arc length direction, with a hole spacing of d.

[0011] Several arc-shaped tiles with the same radius as the inner and outer rings are made to serve as the inner and outer ring sandpaper structures, which we call the inner tile and outer tile, respectively. The tile height is slightly less than c. There are two parallel small holes distributed along the arc length direction on the outer tile at a distance d; there are two parallel threaded holes distributed along the arc length direction on the inner tile at corresponding positions at a distance d.

[0012] Use a rectangular piece of soft sandpaper with a width less than d to cover the bottom of the standard groove ring gauge, attach the beveled edge, extend to the top of the inner and outer rings, press the two ends with inner and outer tiles respectively, and then tighten with bolts through holes.

[0013] The top of the standard groove ring gauge is a disc with a certain thickness and an outer diameter that matches the outer diameter of the ring. The inner hole of the disc is connected to a centering structure or a drive shaft.

[0014] The beneficial effects of this invention are:

[0015] This standard groove ring gauge enhances the stability of the isosceles trapezoidal structure through its outward expansion of the groove top width, downward protrusion of the groove bottom, upward stretching ring, and top disc. Through material selection, heat treatment, and CNC machining, its accuracy can be improved to approach the basic data value of the national standard.

[0016] The central ring avoids the problems of easy detachment and adhesive surface cleaning associated with double-sided adhesive sandpaper. At the same time, it cleverly solves the problem of fixing and replacing abrasive materials of different grits, thereby improving grinding efficiency and surface precision.

[0017] The top disc makes it easier to drive the standard groove ring gauge using a shaft.

[0018] The top disc successfully prevents the bottom isosceles trapezoid from twisting and ellipticizing, giving the grinding fixture the precision of a standard groove ring gauge, making it possible to qualitatively test whether the RJ flange ring groove is standard on-site.

[0019] It should be noted that the specific examples described in this specification are not intended to limit the present invention. The shape, name, size, etc. of the components may vary. All equivalent or simple variations made in accordance with the structure, features and principles described in the present invention should be included within the scope of protection of the present invention. Attached Figure Description

[0020] Figure 1 Schematic cross-sectional view of the RJ flange annular groove structure

[0021] Figure 2. Schematic diagram of the diameter section of the standard groove ring gauge

[0022] Figure 3 is a schematic diagram of the assembly of the RJ flange annular groove sealing surface grinding using a standard groove ring gauge. Detailed Implementation

[0023] Based on the specifications of the RJ ring groove flange to be inspected, select the standard groove ring gauge corresponding to the ring number, select several narrow rectangular fine sandpaper bottom ring gauges, apply them to the bevel and the vertical surface of the ring, and then press them tightly with arc-shaped blocks.

[0024] Push the ring gauge into the ring groove, press it firmly, and slowly rotate the ring gauge a few times before taking it out for inspection. Areas without fine sandpaper grinding marks indicate that the machining dimensions are inaccurate, while severely ground areas are support hard points. This operation can effectively detect machining defects in the ring groove.

[0025] During inspection, it was found that only the inner or outer ring was ground, which indicates that the ring groove has a pitch circle symmetry defect; if during inspection, it was found that only a very narrow area of ​​the lower or upper edge of the bevel was ground, it indicates that the bevel angle of the ring groove is deviated.

[0026] After repeatedly changing the sandpaper and polishing, the defects will gradually shrink until they disappear completely. Finally, polishing with fine sandpaper can achieve a surface roughness of 0.4μm, and the repair process is complete.

[0027] After the above operations using a standard groove ring gauge, the depth and width of the octagonal gasket ring groove are increased proportionally. Deviations in the manufacturing process, such as the ring groove pitch diameter, the angle of the inclined plane, and the symmetry of the inclined plane about the pitch circle, are corrected by the standard groove ring gauge. The octagonal gasket used does not need to be changed; only the gap between the upper and lower flanges is reduced.

[0028] Therefore, this invention simplifies complex issues and efficiently and ingeniously solves the technical challenges of on-site maintenance of RJ annular flanges. The on-site maintenance results of annular flanges at Wanhua Chemical Group Co., Ltd.'s water washing tower unit, Shandong Huaxing Petrochemical Group Co., Ltd.'s diesel hydrogenation unit, and Dezhou Hualu Hengsheng Chemical Co., Ltd.'s coal gasification furnace top burner unit also verify the overall effectiveness of this technology.

Claims

1. This invention discloses a grinding fixture for RJ flange ring grooves. The fixture includes: The bottom conformal RJ flange annular groove cross-section structure, the arc-shaped tile sandpaper-pressing structure on the middle annular structure, and the top disc reinforcement structure for overall jig stability and its inner hole centering structure connected to the drive shaft—these three parts together realize the overall function of this invention.

2. The features of this invention are: a grinding jig skeleton at the bottom that conforms to the cross-section of the RJ flange ring groove; a set of arc-shaped tiles for easy replacement of coarse and fine abrasive paper, which are attached to the jig inside and out, and the abrasive paper wrapped around the jig skeleton is pressed tightly through bolt holes; and a disc that strengthens the jig ring structure is connected to the drive shaft, realizing motorized operation.

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