JP7661335B2 - Gasket management method, system, and program - Google Patents

Description

The present disclosure relates to a management technique for gaskets used, for example, in fastening piping systems.

The tightening torque and bolt axial force applied to the flanges by the bolts are traditionally used to tighten gaskets. The tightening torque and bolt axial force are information related to the tightening of the bolts that fasten the flanges together.

Regarding the tightening of this gasket, a system is known that uses tightening surface pressure corresponding to the type of gasket and internal fluid, multiple tightening forces, bolt-related information, etc. to grasp the tightening torque (for example, Patent Document 1). Regarding the tightening of a bolt, it is known to convert the strain generated in the bolt into data and visualize the tightening state of the bolt (for example, Patent Document 2). Also known is a system that uses a sheet-type pressure sensor embedded inside the gasket to measure the force applied to part of the gasket by tightening (for example, Patent Document 3).

JP 2014-225219 A JP 2015-141345 A Patent No. 4699935

The reason why bolt tightening torque and axial force values are used to manage gasket tightening is that bolts are the means for tightening flanges, and by measuring bolt strain, the tightening force applied to the gasket by the bolt can be easily determined.

However, a careful examination of the relationship between the bolts, flanges and gaskets revealed that the bolt tightening force acts on the flange, and only indirectly acts on the gasket via the flange. In other words, the flange receives the load caused by the tightening of the bolts, and this load only acts on the gasket via the flange. The torque and axial force values applied to the bolts are loads acting on part of the flange, and do not represent the surface pressure acting on the gasket.

For this reason, gasket tightening management poses the following challenges:

a) The torque and axial force values obtained from the bolt are information about the bolt and cannot be said to measure the surface pressure received by the gasket.

b) In terms of the surface pressure that the gasket receives from the flange, the bolt torque value and axial force value are only indirect information and are only a guide to the surface pressure.

c) The bolt torque and axial force values are affected by the tightening condition of the bolts and flanges, and this tendency to fluctuate cannot be ignored.

When gasket surface pressure is estimated using torque or axial force values measured with a torque wrench or bolt axial force meter, if the tightening condition of the bolts or flanges is affected, the relationship between the surface pressure applied to the gasket (= estimated surface pressure) and the surface pressure actually received by the gasket (= actual surface pressure) is as follows:
Estimated surface pressure ≠ actual surface pressure. Even if the measurement accuracy of torque and axial force values is improved, the estimated surface pressure and the actual surface pressure of the gasket do not match. It is not possible to grasp the surface pressure that the gasket receives.

Regarding this problem, the inventor has found that the change in shape of the gasket depends on the load applied between the flanges, and that observing this change in shape is beneficial in terms of managing the tightening of the gasket. Patent Documents 1 to 3 do not disclose or suggest this problem. Furthermore, the configurations disclosed in Patent Documents 1 to 3 are unable to solve this problem.

Therefore, based on the above problems and findings, an object of the present disclosure is to observe the change in shape of a gasket that is subjected to a load between flanges, and to use the observation results in managing the tightening of the gasket.

In order to achieve the above-mentioned object, according to one aspect of the gasket management method disclosed herein, the method includes a step of applying a load to a gasket having a restraining portion that is restrained between flanges and a non-restraining portion adjacent to the restraining portion , and a step of observing a shape change that occurs in shape observation portions set at multiple locations on the non-restraining portion of the gasket due to the load , wherein in the step of observing the shape change, a strain sensor that detects the amount of change in the shape change is used to obtain shape information including the shape change in the circumferential direction of the gasket at the shape observation portion, and the tightening of the gasket is managed based on the shape information .

In this management method, the shape change further includes either or both of a change in at least the spacing direction between the flanges of the gasket, or a change in the spacing direction and a direction intersecting the spacing direction, and the inflection point of the shape information subjected to Nth-order differentiation is used as a criterion for determining whether tightening of the gasket is complete.

In order to achieve the above-mentioned object, according to one aspect of the management system disclosed herein, the system includes a measuring means for measuring shape changes occurring in shape observation sections set at multiple locations of a non-restrained portion of a gasket that is restrained between flanges and receives a load, a management server for generating management information for managing the fastening between the flanges based on the shape changes, and an information presentation section for presenting the management information , wherein the measuring means is a strain sensor for detecting the amount of change in the shape change and obtains shape information including the shape change in the circumferential direction of the gasket at the shape observation section, and the management server manages the fastening between the flanges based on the shape information.

In order to achieve the above-mentioned object, according to one aspect of the program of the present disclosure, the program is implemented by a computer, and the computer is implemented with the following functions: a load is applied between the flanges to a restraining section where a gasket is restrained between the flanges, and the gasket is subjected to a circumferential shape change in shape observation sections set at multiple locations on the periphery of a non-restraining section adjacent to the restraining section due to the load , and shape information representing the change in the circumferential shape of the gasket due to the load is obtained using a strain sensor that detects the amount of change in the shape change; and a function of generating management information for managing the tightening of the gasket based on the shape information .

According to the present invention, one of the following effects can be obtained:

(1) The change in the shape of the gasket that occurs between the flanges indicates the load that the gasket receives between the flanges and the tightening condition of the gasket, and by observing the change in shape of the gasket, it is possible to control the tightening of the gasket.

(2) The change in shape of the gasket that occurs between the flanges represents the tightening condition of the gasket between the flanges and the airtightness between the flanges, and by directly observing this change in shape from the gasket itself, the tightening condition and the airtightness between the flanges can be easily evaluated.

(3) Compared to the previous method of management using bolt torque values and axial force values, it is possible to improve the accuracy of gasket tightening management without relying on the skill of the worker.

Other objects, features and advantages of the present invention will become more apparent with reference to the accompanying drawings and each embodiment.

3A and 3B are diagrams illustrating a flange fastening portion according to the first embodiment. 2 is a diagram showing a cross-sectional end surface of the line II-II in FIG. 1. FIG. 1 is a diagram showing a gasket management system according to a first embodiment. FIG. 13 is a diagram showing a gasket management database. FIG. 13 is a diagram showing a gasket management system according to a third embodiment. FIG. 1A is a diagram showing a gasket according to Example 1, and FIG. 1B is a diagram showing an example of a shape observation unit for the gasket. FIG. 4 is a diagram showing a shape change with respect to a load in the gasket according to Example 1. FIG. 10A is a diagram showing a gasket according to Example 2, FIG. 10B is a perspective view showing an outer cut of the gasket, and FIG. 10C is a diagram showing changes in shape that appear in the outer cut. FIG. 11 is a diagram showing a change in shape with respect to a load in an outer cut according to Example 2. FIG. 10A is a diagram showing a gasket according to Example 3, FIG. 10B is a perspective view for explaining an inner cut, and FIG. 10C is a diagram showing a shape change that appears in the inner cut. FIG. 11 is a diagram showing a shape change with respect to a load in a gasket according to Example 3. FIG. 13 is a diagram showing an example of shape observation of a gasket according to Example 4. 13A is a diagram showing a shape observation example according to Example 4, in which FIG. 13A is a diagram showing shape changes on the outer diameter side and the inner diameter side, and FIG. 13B is a diagram showing shape changes in the circumferential direction and the radial direction. FIG. 10A is a diagram showing the shape of a gasket in accordance with Example 5, FIG. 10B is a diagram showing an example of the state before a load is applied, and FIG. 10C is a diagram showing an example of the state when a load of a predetermined value is applied. 13A and 13B are diagrams illustrating an example of shape observation according to the fifth embodiment.

First Embodiment
Fig. 1 shows a flange fastening portion 2 according to a first embodiment. The configuration shown in Fig. 1 is an example, and the present disclosure is not limited to such a configuration. In Fig. 1, the X-axis, the Y-axis, and the Z-axis are shown at the center of the flange fastening portion 2 as an example.
Pipes 4-1 and 4-2 are arranged in the Z-axis direction in this flange fastening portion 2. A flange 6-1 is formed in the pipe 4-1 as a fastening means for connecting with the pipe 4-2. A flange 6-2 is formed in the pipe 4-2 as a fastening means for connecting with the pipe 4-1.

A gasket 8 is disposed between the flanges 6-1, 6-2. A plurality of bolts 10 are inserted between the flanges 6-1, 6-2 at predetermined angular intervals (for example, 45 degrees), and each bolt 10 is fastened with a nut 12.
The gasket 8 is a sealing member between the flanges 6-1 and 6-2, and is, for example, a sheet gasket made of a mixture of PTFE (Polytetrafluoroethylene) and a filler. The gasket 8 may be made of a resin or rubber other than PTFE. The gasket 8 may be made of a metal material, or may be made of a combination of a metal material and ceramic, a heat-resistant fiber material, or other material. The gasket 8 may be a spiral gasket 80 (FIG. 5), a flat gasket with a sheet of PTFE or graphite attached to the surface, a cam profile gasket with a groove formed on the surface of the gasket or a flange on the outer edge, etc.

This gasket 8 has a restrained portion 8-1 on the inner periphery and a non-restrained portion 8-2 on the outer periphery. The restrained portion 8-1 is sandwiched between and restrained by the flanges 6-1, 6-2, and is the area that is in contact with the flanges 6-1, 6-2 and receives a load F from the flanges 6-1, 6-2. This load F is the tightening load applied by each bolt 10 and nut 12.

The non-restrained portion 8-2 is integral with the restrained portion 8-1, is not restrained by the flanges 6-1 and 6-2, and is the area on the peripheral side of the gasket 8. In other words, the non-restrained portion 8-2 is not in contact with the flanges 6-1 and 6-2, is not restrained by the flanges 6-1 and 6-2, and is an area that does not receive the load F from the flanges 6-1 and 6-2.

The non-restrained portion 8-2 has multiple shape observation sections 14-1, 14-2, 14-3, and 14-4. Each shape observation section 14-1, 14-2, 14-3, and 14-4 is an area for observing the shape change that appears in the non-restrained portion 8-2 due to the load F received by the restrained portion 8-1. In this first embodiment, an observation plane formed by the X-axis and Y-axis is assumed, and shape observation sections 14-1, 14-2, 14-3, and 14-4 of arbitrary widths are arranged at angular positions set at 90 degree intervals.

<Cutting surface of line II-II in Figure 1>
Fig. 2 shows a cut end surface taken along line II-II in Fig. 1. The restrained portion 8-1 is sandwiched and restrained between the gasket seats 16 of the flanges 6-1, 6-2. In contrast, the non-restrained portion 8-2 protrudes into the gap 18 between the flanges 6-1, 6-2. The end of the gasket 8 is a free end where, when the restrained portion 8-1 is subjected to a load F, strain due to this load appears as a change in shape in the non-restrained portion 8-2, forming a cantilever beam.

<Observation of shape changes occurring in the unconstrained portion 8-2>
When the bolts 10 and nuts 12 are tightened to fasten the flanges 6-1, 6-2 together, the restraining portion 8-1 of the gasket 8 receives a load F from between the flanges 6-1, 6-2.

When the gasket 8 receives this load F, a strain is generated in the restrained portion 8-1, and this strain causes a change in shape in the unrestrained portion 8-2. The amount of this change in shape corresponds to the load F.

This shape change varies depending on the magnitude and direction of the load F. This shape change includes changes in the spacing direction (Z-axis direction) between the flanges 6-1, 6-2 and in directions intersecting this spacing direction (X-axis direction, Y-axis direction). The shape change of the gasket 8 in the first embodiment includes changes in the thickness direction, radial direction, or circumferential direction of the gasket 8.

<Gasket 8 Management Process>
The management process of the gasket 8 is an example of a management method of the present disclosure. This management process includes a process S1 of generating the constrained portion 8-1 and the non-constrained portion 8-2, a process S2 of applying a load F, a process S3 of acquiring shape information, and a process S4 of presenting the shape information, etc. S1 to S4 attached to each process indicate the order of each process, and the cited terms are used merely for convenience.

Process S1 for generating the restraint portion 8-1 and the non-restraint portion 8-2: When the gasket 8 is placed between the flanges 6-1, 6-2, the portion of the gasket 8 that contacts the flanges 6-1, 6-2 becomes the restraint portion 8-1, and the portion of the gasket 8 that does not contact the flanges 6-1, 6-2 becomes the non-restraint portion 8-2. In other words, the restraint portion 8-1 and the non-restraint portion 8-2 of the gasket 8 are generated by being placed between the flanges 6-1, 6-2.

Load F application process S2: A load F is applied to the restrained portion 8-1 of the gasket 8, which is restrained by the flanges 6-1 and 6-2, by tightening the flanges 6-1 and 6-2. In response to this load F, the restrained portion 8-1 distorts, causing a change in shape in the non-restrained portion 8-2.

Shape information acquisition process S3: The management server 24 (Figure 3) acquires shape information including shape changes occurring in the non-restrained portion 8-2.

Presentation step S4 of shape information, etc.: The management server 24 generates presentation information including the shape information, and presents it by the information presentation unit 26 (FIG. 3).
In addition, the shape information acquired in the shape information acquisition step S3 may be subjected to N-th order differentiation (multi-stage differentiation) to highlight the change points of the shape information. If the result of this processing is reflected in the presented information in the presentation step S4, the change points of the shape information can be clarified.

<Gasket Management System 20>
Fig. 3 shows a gasket management system 20 according to a first embodiment. This gasket management system 20 is a system for executing the above-mentioned management process by information processing. The configuration shown in Fig. 3 is an example, and the present disclosure is not limited to such a configuration. In Fig. 3, the same parts as in Fig. 2 are given the same reference numerals.
The gasket management system 20 includes a strain sensor 22, a management server 24, and an information presentation unit 26.

The strain sensor 22 is an example of a measuring means for measuring the shape change from the shape observation unit 14 set in the non-restrained portion 8-2, and outputs a detection signal that indicates the amount of change in shape that has occurred in the shape observation unit 14. This strain sensor 22 may be a laser displacement meter, a camera, or the like, which is a device that detects the shape change and converts it into an electrical signal.

The laser displacement meter shines laser light on the shape observation unit 14, detects changes in the shape of the shape observation unit 14 using reflected light, and observes the amount of change. The camera captures an image of the shape observation unit 14, and the management server 24 detects the shape changes detected by the strain sensor 22 in terms of the number of pixels, and obtains shape change information corresponding to the strain.

The management server 24 is composed of a computer with communications capabilities. This management server 24 comprises a processor 28, a memory unit 30, an input/output (I/O) unit 32, and a communications unit 34. The processor 28 executes the OS (Operating System) and management programs in the memory unit 30, and performs information processing for gasket management. The memory unit 30 includes a storage medium for storing the OS and management programs. This memory unit 30 stores a gasket management database (DB) 36 (Figure 4). Under the control of the processor 28, the communications unit 34 links with a management terminal (not shown) to input and present information. The management terminal is also used to obtain shape information and write and read from the gasket management DB 36.

In addition, the information presentation unit 26, under the control of the management server 24, presents management information including load information and judgment information associated with change information representing the shape change.

<Information processing by management server 24>
The information processing of the management server 24 includes the following steps:
This includes processes such as a) inputting the detection output of the strain sensor 22, b) obtaining shape information of the gasket 8 including the shape change of the non-constrained portion 8-2, and c) presenting information by the information presenting unit 26.

<Gasket Management DB36>
4 shows an example of the gasket management DB 36. The gasket management DB 36 stores a gasket management file 38.
In this gasket management file 38, a gasket information section 40, a shape detection information section 41, a time information section 42, a load information section 44, a strain sensor information section 46, a detection information section 48, and a history information section 50 are set as examples of gasket management information.

The gasket information section 40 stores identification information for the gasket 8 as well as specification information for identifying the gasket 8.

The shape detection information section 41 stores information about the shape observation sections 14-1, 14-2, 14-3, and 14-4, such as shape observation section information such as the form and placement position of Example 1 (Figure 6), Example 2 (Figure 8), and Example 3 (Figure 10).

The time information section 42 stores time information such as the observation date and time.

The load information section 44 stores load information such as the load F applied between the flanges 6-1, 6-2 by tightening the bolt 10 and the load conditions.

The strain sensor information section 46 stores information such as the type of sensor used to observe shape changes.

The detection information section 48 stores the detection values obtained by the strain sensor 22 from the shape observation sections 14-1, 14-2, 14-3, and 14-4.

The history information section 50 stores history information such as observations of shape changes and loads, and information presentation.

Effects of the First Embodiment
According to the first embodiment, any one of the following effects can be obtained.

(1) The change in shape of the gasket 8 occurs due to the load that the gasket 8 receives between the flanges 6-1 and 6-2, and represents the tightening state of the gasket 8. Therefore, by observing the change in shape using the shape observation unit 14 of the gasket 8, the tightening state of the gasket 8 can be grasped and the tightening state can be managed.

(2) The change in shape of the gasket 8 represents the airtightness between the flanges 6-1 and 6-2 provided by the gasket 8 between the flanges 6-1 and 6-2, and by directly observing this change in shape from the gasket itself, the airtightness between the flanges 6-1 and 6-2 can be easily evaluated.

(3) Compared to the conventional method of management using bolt torque values and axial force values, it is possible to improve the accuracy of tightening management of the gasket 8 without relying on the skill of the worker.

Second Embodiment
The method for managing a gasket 8 according to the second embodiment further includes an estimation step S5 using inflection point information in addition to the management method according to the first embodiment.
In the estimation process S5 using inflection point information, the shape information includes inflection point information of a shape change caused by a specific load F, and the management server 24 can calculate the load F to be applied to the gasket 8 from the inflection point.

An inflection point represents a state where the shape of the gasket 8, for example in the circumferential direction, changes significantly, and includes a minimum point. A minimum point is a point where the direction of the shape change changes, for example, a transition point from a compressed state to an elongated (tensile) state, or from an elongated (tensile) state to a compressed state.

<Advantages of the Second Embodiment>
According to the second embodiment, any one of the following effects can be obtained.

(1) Inflection point information can be obtained from shape information as specific information of shape change.

(2) By correlating this inflection point information with the load F to be applied to the gasket 8, the inflection point information can be confirmed from the shape information, thereby optimizing the load on the gasket 8.

(3) Load setting and load adjustment for the gasket 8 can be simplified.

Third embodiment
FIG. 5 shows a gasket management system 20 according to a third embodiment.
The configuration shown in FIG. 5 is just an example, and the technology of the present disclosure is not limited to such a configuration.

This gasket management system 20 is disposed between the flanges 6-1 and 6-2, and uses a spiral-shaped gasket 80 as an object for observing changes in shape due to a load F applied from the flanges 6-1 and 6-2. As shown in Figure 5, for example, this gasket 80 is a laminate in which multiple members with different diameters are arranged coaxially, and includes an outer ring 801, a gasket body 802, and an inner ring 803.

The outer ring 801 and the inner ring 803 are made of a metal material such as stainless steel, carbon steel, or titanium, and are formed into a ring of a predetermined thickness or a shape close to that.

The gasket body 802 is formed by winding a laminate of a thin plate-like member made of, for example, a metal material and a buffer material (filler) such as graphite or fluororesin in a spiral shape between the inner wall surface of the outer ring 801 and the outer wall surface of the inner ring 803. The laminate that constitutes the gasket body 802 is formed, for example, with a cross section that is "V" shaped or a waveform similar thereto. The end faces of this laminate are fixed to the outer ring 801 and the inner ring 803 by spot welding, for example.

In the gasket 80, for example, at the flange fastening portion 2, only the inner ring 803 or the inner ring 803 and part or all of the gasket body 802 and part of the outer ring 801 may be in contact with the gasket seat 16 (Fig. 2) to form the restrained portion 8-1 that receives the load F. In other words, in the gasket 80, part or all of the outer ring 801 becomes the non-restrained portion 8-2. In the gasket 80, the gasket body 802 deforms in response to the load F from the flanges 6-1 and 6-2, and this deformation causes strain in the outer ring 801.

In this gasket management system 20, for example, a shape observation unit 14 is set in a part of the outer ring 801, which is the non-constrained portion 8-2, and a shape change such as a strain occurring in this outer ring 801 is measured by a strain sensor 22. Then, the gasket management system 20 grasps the load F applied to the gasket 80 and the fastening state of the gasket by utilizing the amount of change in the shape change. The management process of the fastening state of the gasket 80 may be performed in the same manner as in the above embodiment.

<Advantages of the Third Embodiment>
According to the third embodiment, any one of the following effects can be obtained.

(1) The same effects as those of the first and second embodiments are obtained.

(2) Even when a spiral-wound gasket 80 is used, the tightening state can be grasped by measuring the change in shape of the non-constrained portion 8-2 between the flanges 6-1, 6-2.

Example 1
6A shows a gasket 8 according to Example 1. In this Example 1, a restraining portion 8-1 and a non-restraining portion 8-2 are set concentrically with the same or nearly the same width. The restraining portion 8-1 is on the same plane on the gasket 8 and may be an area that is automatically determined as a contact portion with the gasket seat 16 of the flanges 6-1 and 6-2 described above, and the non-restraining portion 8-2 may be an area outside the gasket seat 16.

B of Figure 6 shows a gasket 8 in which multiple shape observation sections 14-1, 14-2, 14-3, and 14-4 are arranged. Each shape observation section 14-1, 14-2, 14-3, and 14-4 is arranged in the non-restraint section 8-2 at angular intervals of a central angle of 90 degrees. θ indicates the angular range in which the shape observation sections 14-1, 14-2, 14-3, and 14-4 are set. The arrangement positions of each shape observation section 14-1, 14-2, 14-3, and 14-4 may be set at positions that do not overlap with the arrangement position of the bolt 10, but are not limited to this.

Figure 7 shows the load [kN] on the horizontal axis and strain (shape change) on the vertical axis, with angles = 0 (deg), 45 (deg), and 90 (deg) as parameters, and shows the shape changes occurring in the gasket 8 of Example 1 as measured values measured by the strain sensor 22.

m1 indicates the deformation of the gasket 8 in the 0 (deg) direction (= the circumferential direction of the gasket 8), m2 indicates the deformation of the gasket 8 in the 45 (deg) direction, and m3 indicates the deformation in the 90 (deg) direction (= the thickness direction of the gasket 8).

When the restrained portion 8-1 receives a load F from the flanges 6-1 and 6-2 in this manner, a shape change corresponding to the load F occurs in the non-restrained portion 8-2.
This shape change has an inflection point, and the optimum load F can be identified from the relationship between the load F applied to the gasket 8 and the inflection point of the shape change, and can be used as information for determining whether the initial fastening has been completed.

Example 2
8A shows a gasket 8 according to Example 2. In Example 2, similar to Example 1, a restraining portion 8-1 and a non-restraining portion 8-2 are set concentrically with the same width or approximately the same width.

In the non-restraint portion 8-2, an outer cut 54 is formed in each of the shape observation portions 14-1, 14-2, 14-3, and 14-4. This outer cut 54 is formed in the outermost edge of the non-restraint portion 8-2 of the gasket 8, and has a notch shape with a non-closed portion in part.

In Example 2, multiple outer cuts 54 are formed in the gasket 8, and each outer cut 54 is arranged at angular intervals of a central angle of 90 degrees in the non-restrained portion 8-2.

8B, the outer cut 54 is a groove of a constant width W1 cut from the peripheral surface of the gasket 8 toward the center by a constant length L1, penetrating the top and bottom surfaces of the gasket 8. In other words, the outer cut 54 has a vertical surface portion 56 on the inside of the gasket 8, and opposing parallel surface portions 58, 60 with a constant width W1.

When a load F is applied from the flanges 6-1, 6-2 to the restraint portion 8-1 of a gasket 8 equipped with such an outer cut 54, as shown in Fig. 8C, the vertical surface portion 56 expands as indicated by arrow a and displaces in the circumferential direction in response to the load F. In addition, the parallel surface portions 58, 60 expand in the circumferential direction as indicated by arrows b and c. At this time, the edge surface of the gasket 8 extends outward as indicated by arrow d.

Such shape changes can be easily detected by the strain sensor 22. A sensor member such as a metal or resin may be installed in the space of the outer cut 54, and the shape changes of the outer cut 54 may be detected from this sensor member.

Figure 9 shows the relationship between the load and the shape change that occurs in the gasket 8 of Example 2, with the horizontal axis representing the load [kN] and the vertical axis representing the opening width (shape change) [mm] of the outer cut 54. Similarly, Table 1 shows the relationship between the opening width W2 of the outer cut 54 and the load F.

When the restraint portion 8-1 receives a load F from the flanges 6-1 and 6-2 and the load F on the restraint portion 8-1 increases, the opening width W2 of the outer cut 54, which represents the shape change in response to the load F, increases. An inflection point occurs in this shape change. Therefore, when using Example 2, the relationship between the shape change and the load F can be identified by targeting the inflection points of the shape change that appear in the shape observation portions 14-1, 14-2, 14-3, and 14-4.

Example 3
10A shows a gasket 8 according to Example 3. In Example 3, similar to Examples 1 and 2, a restraining portion 8-1 and a non-restraining portion 8-2 are set concentrically with the same width or approximately the same width.

In the non-restraint portion 8-2, an inner cut 62 is formed in each of the shape observation portions 14-1, 14-2, 14-3, and 14-4. The inner cut 62 is a through hole formed in the non-restraint portion 8-2 of the gasket 8.

Each inner cut 62 is arranged at an angular interval of 90 degrees around the central angle in the non-restraint portion 8-2, but is not limited to this.

10B, the inner cut 62 is an arc-shaped groove of a constant width W3 concentric with the periphery of the gasket 8, penetrating the top and bottom surfaces of the gasket 8. In other words, the inner cut 62 has vertical surface portions 64, 66 on the inside of the gasket 8, and concentric arc portions 68, 70 facing each other with a constant length L2 and width W3.

When a load F is applied from the flanges 6-1 and 6-2 to the restraint portion 8-1 of the gasket 8 having such an inner cut 62, the distance between the arc portions 68 and 70 decreases as shown by the arrows e and f in Fig. 10C in response to the load F, and the edge surface of the gasket 8 extends outward as shown by the arrow g. Such a change in shape can be easily detected by the strain sensor 22.

In addition, a sensor member made of metal or resin may be installed in the space of the inner cut 62, and changes in the shape of the inner cut 62 may be detected from this sensor member.

Figure 11 shows the relationship between the shape change and load that occurs in the gasket 8 of Example 3, with the horizontal axis representing the load [kN] and the vertical axis representing the strain (shape change) of the inner cut 62.

When the restraint portion 8-1 receives a load F from the flanges 6-1 and 6-2 and the load F on the restraint portion 8-1 increases, the shape of the inner cut 62, which represents the change in the load F, changes. This shape change has a minimum point included in the inflection point, and in this Example 3 as well, it is possible to specify the relationship between the shape change and the load F by targeting such a minimum point. As described above, this minimum point is the point where the direction of the shape change appearing in the non-restraint portion 8-2 of the gasket 8 changes, in other words, the transition point where the inner cut 62 transitions from a compressed state to an elongated (tensile) state, or from an elongated (tensile) state to a compressed state.

Therefore, according to Example 3, in the relationship between the load F and the shape change, a minimum point appears conspicuously due to the shape change in the circumferential direction, but there are also cases where the minimum point is equal to the inflection point. Also, there are also cases where the shape change in the circumferential direction produces not a minimum point, but an inflection point where the shape change in the circumferential direction changes significantly.

<Detection of inflection points in shape information and tightening criteria>
As shown in the first, second and third embodiments, an inflection point can be generated in the shape information corresponding to a specific load F. This makes it possible to estimate the specific load F from the inflection point of the shape information when tightening the flanges 6-1 and 6-2, and to use this as a criterion for determining whether tightening is complete.

<Comparison of Examples 1, 2, and 3>

Table 2 shows the shape, shape changes, and inflection points for Example 1 (= outer cut 54 and inner cut 62: none), Example 2 (= outer cut 54), and Example 3 (= inner cut 62).

In Example 1, the outer cut 54 and the inner cut 62 are not processed.
In Example 2, the outer cut 54 was formed with a width W1 of 1 mm and a length L1 of 3 mm.
In Example 3-1, the inner cut 62 was set to have a width W3 of 1 mm and a length L2 of 30 mm.
In Example 3-2, the width W3 was set to 2 mm and the length L2 was set to 30 mm.
In Example 3-3, the width W3 was set to 1 mm and the length L2 was set to 50 mm.

In Example 1, an inflection point load of 140 kN was obtained from the change in shape in the circumferential direction, and a minimum point load was not obtained.
In Example 2, an inflection point load of 125 kN was obtained from the change in shape in the circumferential direction, and a minimum point load was not obtained.
In Example 3-1, an inflection point load of 135 kN was obtained from the change in shape in the circumferential direction, and a minimum point load of 135 kN was obtained.
In Example 3-2, an inflection point load of 115 kN was obtained from the change in shape in the circumferential direction, and a minimum point load of 115 kN was obtained.
In Example 3-3, an inflection point load of 120 kN was obtained from the change in shape in the circumferential direction, and a minimum point load of 120 kN was obtained.

Effects of Examples 1, 2, and 3
As is clear from Examples 1, 2 and 3, in the outer cut 54, the appropriate load F can be estimated by measuring the opening width W2 of the cut shape from the side. When using the outer cut 54 for shape detection, the opening width W2 of the outer cut 54 is measured in advance for each load F applied to the gasket 8, and the load F can be estimated by comparing the opening width W2 with the actual measured value. This estimation can be performed by creating a database of the opening width W2 of the outer cut 54 for each load F, and easily and accurately calculating the load F by comparing it with the actual measured value of the shape change.

In the inner cut 62, a load F is applied to the flanges 6-1 and 6-2, and a significant change occurs as the inner wall surface of the through-hole-shaped inner cut 62 closes (comes into contact).

Unlike torque management or bolt axial force measurement, such monitoring and measurement of shape changes measures the shape changes of the non-restrained portion 8-2 (Example 1), the outer cut 54 (Example 2), and the inner cut 62 (Example 3), and can obtain changes representing the load F from the gasket 8. Therefore, the load F applied to the flanges 6-1, 6-2 can be estimated from the shape changes of the gasket 8 without being affected by the bolt 10 or the flanges 6-1, 6-2.

It was confirmed that the processing shapes of the outer cut 54 and inner cut 62 enable the gasket 8 to accommodate a variety of diameters and thicknesses.

Example 4
12 shows a configuration example of a gasket 80 according to Example 4. In Example 4, for example, at least an outer ring 801 of a spiral-shaped gasket 80 constitutes a non-constrained portion 8-2. In Example 4, shape changes Qa and Qb on the outer edge side and inner edge side of the outer ring 801 of the gasket 80 that expand and contract in the circumferential direction, and shape change R that expands and contracts in the radial direction of the gasket 80 are measured.

<Measurement of circumferential shape changes Qa, Qb>
FIG. 13A shows the load [kN] on the horizontal axis and the circumferential strain (shape change) on the vertical axis, and shows the measurement values of the shape change Qa appearing on the outer edge of the outer ring 801 and the shape change Qb appearing on the inner edge, measured by the strain sensor 22.

The strain on the inner edge of the outer ring 801 is greater than the strain on the outer edge. In other words, the outer ring 801 undergoes greater shape changes on the inner edge, making it easier to detect the behavior of the gasket 80 or the gasket body 802 due to the load F.

<Measurement of circumferential shape change Qb and radial shape change R>
FIG. 13B shows the load [kN] on the horizontal axis and the strain (shape change) on the vertical axis, and shows the measurement values of the circumferential shape change Qb appearing on the inner edge of the outer ring 801 and the radial shape change R measured by the strain sensor 22.

From these measurement results, it can be seen that in the circumferential shape change Qb, the measurement value increases in the positive direction as the gasket surface pressure increases, indicating that a tensile force is acting. In addition, in the radial shape change R, the measurement value increases in the negative direction as the gasket surface pressure increases, indicating that the gasket is in a compressed state.

Example 5
14A shows a configuration example of a gasket 80 according to a fifth embodiment. In this fifth embodiment, for example, at least an outer ring 801 constitutes the non-constraint portion 8-2. In this fifth embodiment, an inner cut 82 of a predetermined length is formed along the outer periphery of a part of the outer ring 801 of the gasket 80. This inner cut 82 is a through hole formed in the non-constraint portion 8-2 of the gasket 8. This inner cut 82 is formed at a position that is a predetermined distance t of 5 mm from the outer edge of the outer ring 801. In this fifth embodiment, a shape observation unit 14 is provided, for example, on the outer edge portion along the position where the inner cut 82 is formed.

As shown in FIG. 14B, before a load F from the flanges 6-1 and 6-2 is applied to the gasket body 802, the outer ring 801 has a predetermined width of, for example, 0.1 mm.
When a load F is applied through the gasket body 802, the outer ring 801 deforms partially or entirely at the opening, forming a closed inner cut 82b, as shown in Fig. 14C. In Example 5, the gasket surface pressure due to the load F and the shape change Qc of the outer ring 801 in the state of the inner cut 82b are measured.

Figure 15 shows the load [kN] on the horizontal axis and strain (shape change) on the vertical axis, and shows the measurement values measured by the strain sensor 22 of the circumferential shape change Qc that appears on the outer edge corresponding to the formation position of the inner cut 82b of the outer ring 801.

In the measurement results, when the load on the gasket increases, for example, there is no significant change in strain from when the load begins to be applied until a certain value is reached, and then when the load exceeds the certain value, a negative value is measured by the strain sensor. This indicates that a change in shape has occurred, for example, indicating that the outer edge of the outer ring 801 has been compressed in the circumferential direction. Then, for example, the circumferential strain reaches a minimum point when the load is around 220 kN, and then increases in value in the positive direction.

Effects of Examples 4 and 5
According to the fourth and fifth embodiments, the following effects can be expected.

(1) By measuring the change in shape of the outer ring 801 of the spiral-shaped gasket 80 sandwiched between the flanges 6-1 and 6-2, the surface pressure of the gasket 80 due to the load F can be determined.

(2) In the spiral-shaped gasket 80, due to the geometric characteristics of the gasket body 802, which is formed in a spiral shape, there are differences in the strain state depending on the measurement position of the outer ring 801, making it possible to grasp the state of the gasket and the load state in detail.

(3) Since the gasket body 802 and the outer ring 801 of the spiral-wound gasket 80 are separate members, the tendency for strain to form in the non-restrained portion 8-2 in response to the load F from the flanges 6-1, 6-2 is different from that of a sheet gasket constructed from a single member. However, the load F applied from the flanges 6-1, 6-2 can be estimated from the change in shape of the gasket 80.

(4) The inner cut 82 formed in the spiral-shaped gasket 80 has an opening that is closed by the load F from the flanges 6-1 and 6-2, resulting in a significant change in the strain generated in the outer ring 801.

(5) In the flange fastening portion 2 using the spiral gasket 80, unlike torque management or bolt axial force measurement, monitoring and measurement of shape change can be performed by measuring the shape changes Qa, Qb, R (Example 4) that occur in the outer ring 801 and the shape change of the inner cut 82 (Example 5), thereby obtaining a change representing the load F from the gasket 8. Therefore, the load F applied to the flanges 6-1 and 6-2 can be estimated from the shape change of the gasket 80 without being affected by the bolt 10 or the flanges 6-1 and 6-2.

Other Embodiments
(1) Although the outer cut 54 has the vertical surface portion 56 and the parallel surface portions 58, 60 in the second embodiment, these are merely examples. The outer cut 54 may have a shape that does not have the vertical surface portion 56, or the parallel surface portions 58, 60 may be non-parallel, for example, a V-shape.

(2) Regarding the inner cut 62, in Example 3, the concentric arc portions 68, 70 are illustrated, but these are only examples. The inner cut 62 may have a shape in which the arc portions 68, 70 do not have a constant width, and may have parallel or non-parallel surfaces instead of an arc shape.

(3) In the process of presenting shape information, etc. (S4) of the management process of the gasket 8, the management server 24 may generate presentation information by processing the acquired shape information such as multi-stage differentiation, and a display unit that clearly indicates change points may be presented on the information presentation unit 26 (Figure 3).

As described above, the most preferred embodiment of the present disclosure has been described. The present disclosure is not limited to the above description. Various modifications and changes are possible for those skilled in the art based on the gist of the invention described in the claims or disclosed in the description for carrying out the invention. It goes without saying that such modifications and changes are included in the scope of the present disclosure.

The gasket management method, system, and program disclosed herein are useful in that it is possible to observe changes in the shape of the gasket due to the load received from the flanges without measuring the axial force or torque value of the bolts that fasten the flanges, and to calculate the load on the gasket from the shape information without being affected by the tightening state of the bolts or flanges, and this can be used for management information such as gasket replacement.

2 flange fastening portion 4-1, 4-2 pipe 6-1, 6-2 flange 8, 80 gasket 8-1 restraint portion 8-2 non-restraint portion 10 bolt 12 nut 14, 14-1, 14-2, 14-3, 14-4 shape observation portion 16 gasket seat 18 gap 20 gasket management system 22 strain sensor 24 management server 26 information presentation portion 28 processor 30 memory portion 32 input/output (I/O) portion 34 communication portion 36 gasket management database (DB)
38 Gasket management file 40 Gasket information section 41 Shape detection information section 42 Time information section 44 Load information section 46 Strain sensor information section 48 Detection information section 50 History information section 54 Outer cut 56 Vertical surface section 58, 60 Parallel surface section 62, 82 Inner cut 64, 66 Vertical surface section 68, 70 Circular arc section 801 Outer ring 802 Gasket body 803 Inner ring

Claims (4)

applying a load to a gasket having a restrained portion that is restrained between flanges and a non-restrained portion adjacent to the restrained portion ;
observing a shape change caused by the load at shape observation sections set at a plurality of positions of the non-constrained portion of the gasket;
Including,
In the step of observing the shape change, a strain sensor that detects an amount of change in the shape change is used to obtain shape information including the shape change in the circumferential direction of the gasket in the shape observation unit;
A management method comprising the steps of: managing fastening of the gasket based on the shape information . The shape change further includes either or both of a change in a spacing direction between at least the flanges of the gasket, or a change in a direction intersecting the spacing direction,
2. The management method according to claim 1, wherein an inflection point of said shape information obtained by performing N-th order differentiation is used as a criterion for determining whether or not fastening of said gasket is complete. a measuring means for measuring a shape change occurring in shape observation sections set at a plurality of positions in a non-restrained portion of the gasket that is restrained between the flanges and receives a load;
a management server that generates management information for managing the fastening between the flanges based on the shape change;
an information presenting unit that presents the management information;
Including,
the measuring means is a strain sensor that detects an amount of change in the shape change, and acquires shape information including the shape change in the circumferential direction of the gasket in the shape observation unit;
A management system, characterized in that the management server manages the fastening between the flanges based on the shape information . A program for implementing the program on a computer,
a function of receiving a load from between the flanges on a restraining portion where the gasket is restrained between the flanges, and acquiring shape information representing a change in the circumferential shape of the gasket due to the load at shape observation portions set at multiple locations on the periphery of a non-restraining portion adjacent to the restraining portion , using a strain sensor that detects the amount of change in the shape ;
a function of generating management information for managing fastening of the gasket based on the shape information ;
A program for realizing the above on the computer.

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