JP6196721B1 - Gasket for glass lining equipment and manufacturing method thereof - Google Patents

Abstract

To provide a method for manufacturing a gasket for a glass lining device having a relatively large diameter, which can maintain sealing performance even under conditions of a low tightening surface pressure in a determined glass lining and long-term stress relaxation. An annular or elliptical outer peripheral portion and an annular or elliptical inner peripheral portion connected to an inner side edge of the outer peripheral portion are formed. The outer peripheral portion includes an inner core member and the inner core member. A glass lining device gasket provided with a covering member surrounding the core member, wherein the core member is made of corrugated steel pipe and expanded graphite surrounding the corrugated steel pipe, and the covering member is made of a porous PTFE membrane, The PTFE membrane is composed of a seamless PTFE jacket surrounding the PTFE membrane, and one or more holes having an inner diameter of 1 to 2 mm are formed in the outer peripheral portion. [Selection] Figure 1

Description

  The present invention has a relatively small diameter among the dimensions specified in JIS B2404 (dimension of the gasket for pipe flanges), which can maintain the sealing performance even under the condition of the low tightening surface pressure and the long-term stress relaxation in the determined glass lining. The present invention relates to a large gasket for glass lining equipment and a manufacturing method thereof.

A gasket (for example, patent document 1) is used in order to give the apparatus to be used airtightness and liquid-tightness.
Among the equipment using gaskets, equipment with glass lining, such as a stirrer, is particularly sensitive to the occurrence of flowering phenomenon due to polymerization reaction when it comes into contact with the air when the monomer liquid used leaks. Is done.

Usually, the pressure in the tank sealed by the fluctuation of the rotation speed of the stirrer always varies with the amount of suction and the amount of extrusion, and the operation is often performed under high vacuum conditions.
Thus, gaskets used in agitators must be particularly careful with chemical reactions when the conditions of use are severe and the fluids used must not leak. In addition, the gasket and flanges must all be able to withstand chemicals.
Since most PTFE wrapping gaskets used in the currently popular agitators are not gaskets that satisfy these performances, new development has been desired.

Although the glass lining applied to the equipment of a stirrer or the like to compensate for the sealing performance by the gasket to be used etc. 殆because it is difficult to precision machining of the finished surface, gasket conditions used in these, stop the leakage by with a minimum of clamping force, stress It requires minimizing mitigation and also requires maintenance-free.
However, when tightening the flange with the minimum tightening force, it will be hand-tightened and hinged, so the required tightening force cannot be obtained at present, but if the tightening force is increased, some leakage will stop, but the glass lining surface Since there is a risk of cracking, an appropriate tightening force is required.
In addition, a large tightening force may cause cracking or breakage of the flange surface, and in combination, may cause cracking or breakage of the gasket.

  The conventional PTFE wrapping gasket uses a PTFE jacket with a thickness of 0.5 to 1.0 mm, and has a structure that wraps the cushion material of the sheet-like gasket of the core material, and prevents some stress relaxation. Therefore, a corrugated core material using SUS material may be used in combination. What is important for securing and maintaining a seal structure in addition to these wave structures is a method for processing the PTFE jacket. It is customary to manufacture a small-diameter jacket, particularly a jacket having a diameter of 150 mm to 250 mm or less, by lathing from one integrally formed by block molding.

However, when the diameter is larger than 300 mm, the outer cover is made by a method of butting (tape) from a sheet-like film having a thickness of 0.5 mm to 1.0 mm, or by superposition, heat fusion, and low melting point such as PFA and EPA. Usually, bonding is performed using a material, but the seam is very unstable, finishing is difficult, causing leakage, and there is a problem in the processing method of large-diameter gaskets.

  As a method for processing a large-diameter gasket, Patent Document 1 describes a method in which a jacket member made of a belt-shaped member is wound so as to cover the entire outer surface of the core member, but a seam can be formed between the jacket members. The leak could not be completely prevented.

Japanese Patent No. 5514278

The present invention is to solve the problems of the conventional PTFE-covered gasket, seamless in more bore diameter 300 mm, JISB2404 of defined dimensions (the dimensions of the gasket pipe flanges) relatively diameter of large glass-lined To provide a gasket for equipment, and to provide a method for manufacturing a gasket for glass lining equipment having a relatively large diameter capable of maintaining sealing performance even under the conditions of low tightening surface pressure in a predetermined glass lining and long-term stress relaxation. Objective.

Glass-lined equipment gasket of the invention is a tolyl gasket Las lining equipment such from the central core member and the jacket member, and the corrugated steel the wick member is sandwiched between two expanded graphite layer, wherein the 2 A porous PTFE membrane surrounding two expanded graphite layers, the outer cover member is formed of a seamless PTFE outer shell, the PTFE outer shell surrounds the core member, and an outer periphery of the PTFE outer shell One or more holes are drilled in the part and have pressure resistance against a pressure of 0.1 Pa to 3.0 MPa, a gasket for glass lining equipment, with a pressure of 0.1 Pa to 3.0 MPa It is a gasket for glass lining equipment characterized by having pressure resistance, and a management tag may be added thereto.
The method for producing a gasket for a glass lining device according to the present invention includes (a) a step of producing an inner core by adhering expanded graphite to both surfaces of a corrugated steel material , and (b) surrounding the inner core with a PTFE membrane. (C) after the step (b), the step of surrounding the core with a seamless PTFE jacket; and (d) the outer periphery fusion press processing by repeating heating and cooling a plurality of times. a higher row cormorants engineering, a method for producing a glass-lined equipment gasket comprising a step of providing one or more holes in (e) the outer peripheral portion.

Since the gasket for glass lining equipment of the present invention has both an inner peripheral portion and an outer peripheral portion that are annular or elliptical, the surface pressure is uniformly applied as compared with a general gasket for glass lining equipment, so that an appropriate surface pressure is obtained. It is possible.
According to the manufacturing method of the present invention, among the dimensions specified in JIS B2404 (dimension of the gasket for pipe flange), which is seamless, it can be completely sealed with a relatively large caliber and hand-tightened hinge. It is possible to manufacture a gasket for glass lining equipment that does not have any.

FIG. 1 is a sectional view of a gasket for glass lining equipment according to the present invention. FIG. 2 is a diagram comparing the SS curves of the gasket for glass lining equipment of the present invention and the gasket for conventional glass lining equipment. FIG. 3 is a view showing the results of six pressure-sensitive paper tests conducted for each inner diameter shape of the PTFE jacket of the gasket for glass lining equipment of the present invention. FIG. 4 is a sectional view of a conventional gasket for glass lining equipment. FIG. 5 is a diagram showing the results of six pressure-sensitive paper tests conducted for each inner diameter shape of the PTFE jacket of the conventional gasket for glass lining equipment.

[Embodiment]
FIG. 1 shows a cross-sectional view of a glass lining device gasket according to an embodiment of the present invention.
As shown in FIG. 1, the gasket for glass lining equipment of the present invention is composed of a core member (6) and a jacket member (7) surrounding the core member (6).
The core member is composed of a corrugated steel material sandwiched between two expanded graphite layers, and a porous PTFE membrane surrounding the two expanded graphite layers, and the jacket member (7) is a seamless PTFE jacket. (4).
The left side is the outer peripheral part (O), and the right side is the inner peripheral part (I).
One or more holes (5) are formed in the outer peripheral portion of the PTFE jacket.

The characteristics of the gasket for glass lining equipment of the present invention are as follows.
1. The outer peripheral coat thickness is increased by 2 to 3 mm, and the penetration of the monomer-based fluid into PTFE can be delayed.
2. Since the cutting is performed with a diameter of 1500 mm up to a large diameter, there is no seam due to fusion or welding as in the conventional case, and the sealing performance is significantly improved.
In addition, since there is no seam as in the conventional product and there are no steps, a perfect seal can be achieved with a hand-tightened hinge.
3. By buffing the surface roughness to 0.1 μm to 1.0 μm, it is not necessary to use a seal auxiliary material such as gasket paste as in the conventional case.
In addition, it has become possible to use a high-pressure type that is generally impossible by buffing the surface roughness of the seamless PTFE jacket to 0.1 μm to 1.0 μm.
4). As shown in FIG. 1, the inner peripheral portion is circular and the surface pressure is more uniform than that of the general square-shaped glass lining device gasket shown in FIG. 4, so that an appropriate surface pressure can be obtained.

A management tag may be added to the gasket for glass lining equipment of the present invention.
Gaskets degrade in performance when used repeatedly, so adding a management tag prevents overuse and enables safe plant operation.
For example, the management tag may be marked each time it is used so that the number of uses can be known, or the operator can write the number of times.

Next, an example of the manufacturing method of the gasket for glass lining apparatuses of this invention is described.
1. The manufacturing process of corrugated medium on both sides, for example, SUS304 Koruge DOO, pasted expanded graphite, such as M / 8100.
For example, jet one spray may be used as the attaching method.
2. A PTFE membrane having a thickness of 0.04 mm is cut to a width of 30 mm to 50 mm in the width direction, and wound around the core produced in the above process so that the graphite portion is not visible in the form of a gaiter.
3. The core is wrapped with a seamless PTFE jacket, and the outer periphery of the PTFE jacket is temporarily fixed by a stapler or machine sewing.
4). Peripheral fusion press is performed with a special fusion machine. At this time, the temperature condition is preferably 390 ° C./20 seconds. At this time, heating and cooling are repeated while shaping the shape with a jig.
When bonding, it is preferable to use a PFA film of 50 μm.
5. Install the blade to a dedicated sewing machine, cut the outer peripheral portion.
At this time, the fusion margin that is actually fused is at least 3 mm to 10 mm wide, and is visually confirmed.
6). Finally, a hole is drilled at a predetermined location on the outer periphery.

[Example 1]
A gasket for glass lining equipment having an inner ring shape was manufactured by winding a PTFE membrane in a gait shape around a core of M / 8100 attached to a SUS304 corrugate and then covering with PTFE. The dimensions of the annular gasket according to Example 1 used for the experiment were as follows.
・ Radial width (W) is 35.0mm
・ Outer diameter (D4) is 485mm
・ Inner diameter (D1) is 415mm

[Comparative Example 1]
As a comparative example 1, as shown in FIG. 4, a gasket for a glass lining device in which an inner periphery covered with a PTFE jacket (10) is sandwiched between a SUS material (8) and a sheet-like cushion material (9). Manufactured. The dimensions of the gasket of Comparative Example 1 used in the experiment were the same as those of Example 1.

Measure the compression recovery rate of the gasket for glass lining equipment of Example 1 and the gasket for glass lining equipment of Comparative Example 1, and create an SS curve by taking the gasket distortion amount on the X axis and the gasket tightening surface pressure on the Y axis. A comparison is shown in FIG.
The gasket of Comparative Example 1 had a gasket clamping surface pressure at which plastic deformation occurred of about 6 MPa, while the gasket of Example 1 had a pressure of about 11 MPa.
From the above, it can be seen that the present invention can withstand high tightening surface pressure.

Next, a pressure sensitive paper test for each of the inner diameter shapes was conducted at 6 locations obtained by dividing Example 1 and Comparative Example 1 into 6 equal parts, and the results are shown in FIGS. Circles in each figure indicate partial surface pressure load values. The horizontal value indicates the surface pressure inside the circle.
The average pressure at 6 locations of the gasket for glass lining equipment of the present invention is 8.75 MPa, the average effective pressure area ratio is 52.1%, and the average pressure at 6 locations of the gasket for conventional glass lining equipment is 9.9 MPa. The effective pressure area ratio average was 36.4%.
The pressure applied to the pressure-sensitive paper is shown by the difference in color density or color.
It can be seen from FIG. 3 that the gasket for glass lining equipment of the present invention has a white outer diameter part as a whole and is subjected to a surface pressure of 10 MPa or more (maximum measurement limit 12.5 MPa). It is within the range of 10 MPa, and the corrugation of the core corrugation can be seen.
As shown in FIG. 5, in the conventional gasket for glass lining equipment, the white portion is not counted as an effective surface pressure, and the effective surface pressure ratio is lower than that of the present invention and the average pressure is high.
In addition, as compared with the present invention in which the outer diameter portion is white, it can be seen that the conventional gasket for glass lining equipment has a black portion up to the outer diameter side and a portion where pressure is applied is biased.
From the above, it can be said that the surface pressure of the gasket for glass lining equipment of the present invention is more uniform than that of the conventional gasket for glass lining equipment, and an appropriate surface pressure can be obtained.

[Example 2]
As Example 2, a gasket having a nominal diameter of 450 A and a thickness of 7.8 mm ± 0.5 t specified in JISB2202 (gasket seat dimension of the pipe flange) was manufactured by using the gasket for glass lining equipment shown in FIG. The inner pressure (−0.092 MPa to +0.8 MPa) was repeatedly applied at a temperature of 80 ° C. using N ₂ gas as a working fluid.
As a result, leakage was confirmed at the 20th time.

[Comparative Example 2]
As Comparative Example 2, a gasket having a nominal diameter of 450 A and a thickness of 7.8 mm ± 0.5 t specified in JISB 2202 (gasket seat dimensions of the pipe flange) was manufactured by using the gasket for glass lining equipment shown in FIG. The inner pressure (−0.092 MPa to +0.8 MPa) was repeatedly applied at a temperature of 80 ° C. using N ₂ gas as a working fluid.
As a result, leakage was confirmed at the seventh time.

  From the experiments conducted in Example 2 and Comparative Example 2, it was found that the gasket for glass lining equipment of the present invention can withstand repeated use about three times as much as the conventional gasket for glass lining equipment.

  Since the gasket for glass lining equipment of the present invention has no inner diameter shape and no seam, it can apply a stable clamping pressure and does not generate contamination, so that it can be used in a stirrer for producing chemicals and the like.

Claims (3)

It is a gasket for glass lining equipment consisting of a core member and a jacket member ,
The core member is a corrugated steel material sandwiched between two expanded graphite layers;
A porous PTFE membrane surrounding the two expanded graphite layers;
The jacket member is composed of a seamless PTFE jacket,
The PTFE jacket surrounds the core member;
One or more holes are formed in the outer periphery of the PTFE jacket,
A gasket for glass lining equipment, which has pressure resistance against a pressure of 0.1 Pa to 3.0 MPa.   The gasket for glass lining equipment according to claim 1, wherein a management tag is attached to the gasket for glass lining equipment. (A) a process of manufacturing a core by attaching expanded graphite to both surfaces of a corrugated steel material ;
(B) surrounding the core with a PTFE membrane;
(C) after the step (b), surrounding the core with a seamless PTFE jacket; and
(D) and as factories for heating and outer fusing pressing is repeated a plurality of times to cool,
(E) The manufacturing method of the gasket for glass lining apparatuses of Claim 1 or 2 which consists of the process of providing one or more holes in an outer peripheral part.

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