JPH0718487B2 - Spiral wound gasket - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a metal band plate having a corrugated cross section and a band-shaped filler material which are spirally wound a plurality of times in a state of being overlapped with each other. Applied to various pipe joints that seal fluids such as water, oil, steam, and gas, such as used to seal the inside and outside of the pipe by being sandwiched between the flanges formed at each pipe end. It relates to a spiral wound gasket.

[0002]

2. Description of the Related Art A conventional spiral wound gasket of this type is generally one in which a metal strip having a corrugated cross section and asbestos fibers are superposed and wound. That is, the asbestos fibers are more easily formed into paper than other inorganic fibers and become a filler excellent in shape retention, so that a spiral wound gasket using this is extremely excellent in mechanical properties, flexibility, and restorability. It became excellent and was widely used as a material having good heat resistance and sealing properties.

However, recently, the above asbestos fibers are
Since a large amount of dust generated during handling causes lung cancer and causes the asbestos disease in which the dust deposits on the skin and the like, its use has been restricted.

Therefore, there has been a demand for the development of a filler material other than the above-mentioned asbestos fibers. For example, as shown in FIG. 3, a spiral wound gasket using only expanded graphite 22 as a filler has been developed. There is.

[0005]

The spiral wound gasket formed by using the filler material 22 made of only expanded graphite has a temperature range from room temperature to 800 ° C. for a tightening surface pressure of about 350 kgf / cm ^2. Replaces the spiral wound gasket using asbestos fiber filler because it can maintain excellent compression rate and recovery rate compared to those using asbestos fiber filler under temperature conditions, and particularly exhibits excellent sealing performance. It is something that is noticed as a thing.

However, the above conventional product is 1000 k
If an abnormal tightening surface pressure of gf / cm ² is applied,
It has been confirmed that the compressibility is abnormally increased due to buckling and the restoration ratio is reduced, and therefore, there is a problem that the application is limited in this conventional product.

Under these circumstances, the applicant of the present invention, as shown in FIG. 4, has found that the inner-periphery-forming portion 2A of the filler held in a spiral shape has the inorganic filler 21 whose base material is an inorganic material excluding asbestos. Therefore, a spiral wound gasket in which the outer peripheral portion 2B of the filler is composed of expanded graphite filler 22 is proposed. This proposed spiral wound gasket uses the expanded graphite filler 22 of the filler outer peripheral forming portion 2B.
While ensuring the sealing performance by the above, it has the advantage that buckling does not easily occur even when the tightening surface pressure is abnormally high due to the high compression rigidity and high friction coefficient of the inorganic filler 21 of the inner circumference forming portion 2A of the filler. There is.

However, in the above-described structure, as shown in FIG. 15, in the spiral wound forming process, first, the metal strip 1 and the inorganic filler 21 are wound on a spool (not shown) so that the spool 1 and the spool 21 are separated from each other. After being wound around the core 10 for a predetermined number of times while being unrolled, an expanded graphite filler wound spool (not shown) is set in place of the inorganic filler wound spool, and the expanded graphite filler 22 is unrolled together with the metal strip 1 from this spool. However, it must be wound around the inner circumference forming portion 2A of the inorganic filler 21. That is, it takes a very long molding time to replace the spool.

The present invention has been made in view of the above circumstances, and provides a spiral wound gasket which can ensure excellent heat resistance and sealing performance, can prevent buckling, and is excellent in productivity. Is intended.

[0010]

In order to achieve the above object, in a spiral wound gasket according to the present invention, an inner circumference forming portion of a filler held in a spiral shape uses an inorganic material excluding asbestos as a base material. It is characterized in that it is composed of an inorganic filler and an expanded graphite filler that is wound around the inorganic filler, and that an outer peripheral portion of the filler is composed of an expanded graphite filler.

[0011]

The spiral wound gasket configured as described above has a 0.25 between the compression rigidity of the inorganic filler forming the inner circumference forming portion of the spiral wound filler and the flange seating surface of the pipe.
With the above friction coefficient, buckling due to tightening pressure can be prevented, and the expanded graphite filler forming the outer peripheral formation portion of the filler can ensure excellent sealing performance. In addition, when the sealing fluid is a high temperature oxidizing gas, the adiabatic action of the inorganic filler prevents oxidation of the expanded graphite filler. In particular, when forming into a spiral shape, the metal strip, the inorganic filler and the expanded graphite filler are wound around the core a predetermined number of times and the supply of the inorganic filler is completed, and the metal strip and the expanded graphite filler are supplied as they are. Since it only has to be wound,
It is not necessary to replace the expanded graphite filler winding spool during molding, and the molding processing time can be shortened.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of a spiral wound gasket according to the present invention, in which a metal strip 1 holds a filler 2 in a spiral shape. The metal strip 1 has a corrugated cross section as shown in FIG. On the other hand, the filler 2 is composed of an inner circumference forming portion 2A and an outer circumference forming portion 2B, and these forming portions 2A and 2B are continuously spirally wound.

The inner circumference forming portion 2A is composed of an inorganic filler 21 having an inorganic material other than asbestos as a base material and an expanded graphite filler 22 wound around the inorganic filler 21. The inorganic filler 21 is composed of inorganic fibers. , The inorganic powder, the binder, and the like are mixed, and the expanded graphite filler 22 is superposed and wound when the inorganic filler 21 is wound.

As the inorganic fiber, one kind or plural kinds of glass fiber, ceramic fiber, mineral fiber and the like are used. The content of the inorganic fibers is preferably 5 to 40% by weight of the whole inorganic filler. That is, when the content of the inorganic fibers is less than 5% by weight, it becomes difficult to obtain the resilience required as the filler of the spiral wound gasket. On the other hand, if the content exceeds 40% by weight, the porosity of the filler becomes high, so that the sealing property is deteriorated and the fiber is easily broken during tightening, and the strength of the filler is deteriorated.

As the inorganic powder, talc, kaolin, sepiolite, vermiculite, mica, wollastonite, etc. may be used alone or in combination. The content of this inorganic powder is 35 to 95% by weight of the whole inorganic filler.
Is desirable. That is, when the content of the inorganic powder is less than 35% by weight, the filling effect of the inorganic powder is reduced and the filler becomes weak against tightening. On the other hand, if the content exceeds 95% by weight, the flexibility of the filler decreases and the sealing performance deteriorates.

As the binder, natural rubber, synthetic rubber, latex and various pulps are used. The content of the binder is preferably 25% by weight or less based on the whole inorganic funicular. That is, if this binder is contained in an amount of more than 25% by weight, the heat resistance of the inorganic filler will be significantly reduced.

The inorganic filler 21 formed by blending the above-mentioned inorganic fiber, inorganic powder and binder has a thickness of 0.
It is preferably 1 to 1.2 mm. That is, if the thickness of the inorganic filler 21 is less than 0.1 mm, the flexibility and elasticity of the filler will not be utilized regardless of the composition of the inorganic filler 21. On the other hand, if the thickness exceeds 1.2 mm, the compression rigidity and the resilience of the metal strip 1 are impaired, and the compression rigidity, the resilience, and the strength suitable as a filler cannot be obtained.

The inorganic filler 21 preferably has a bulk density in the range of 0.6 to 1.1 g / cm ² . That is, if the bulk density is less than 0.6 g / cm ² , the inorganic filler 21 does not have appropriate compressive rigidity and resilience, and the inorganic filler 2 in this aspect is not obtained.
The existence value of 1 is weakened. The bulk density is 1.1 g / cm.
^{If the} inorganic filler exceeds ² , the compressive rigidity becomes too high and the sealing property deteriorates.

Further, the inorganic filler 21 must be composed so that the coefficient of friction with the flange seat surface of the pipe is 0.25 or more. That is, when the friction coefficient is less than 0.25, when the tightening pressure is applied to the spiral wound gasket, the gap between the gasket inner circumference forming portion formed of the metal strip 1 and the inorganic filler 21 and the pipe flange is increased. Slip occurs on the spiral wound gasket, resulting in flattening of the entire spiral wound gasket, that is, abnormal compression. Therefore, if the coefficient of friction is less than 0.25, the spiral gasket may be abnormally compressed and unrestorable when it is tightened, especially when it is tightened with an abnormal tightening pressure. In such a state, the sealing body draws a spiral-shaped locus and leaks through the gap formed between the metal strip 1 and the filler 2.

Next, the outer peripheral portion 2B of the filler 2 will be described. This outer peripheral formation portion 2B is made of expanded graphite filler 22, and in the case of the embodiment shown in FIG. 1, it occupies the winding portion for three rounds of the spirally wound filler 2 wound for six rounds. In the spiral wound gasket according to the present invention, the outer peripheral portion 2B may occupy at least one or more winding portions of the filler 2 wound a plurality of times. In this way, the outer peripheral formation portion 2B occupies one or more windings in order to reliably prevent axial leakage in the spiral wound gasket by the expanded graphite filler 22 over the entire circumference. Is.

At the same time, the outer peripheral portion 2B, that is, the volume content of the expanded graphite filler 22 is 70% or less of the total filler. This is because when the volume content of the expanded graphite filler 22 exceeds 70%, the filler 2
This is because even if the other part is made of the inorganic filler as described above, sufficient compression rigidity cannot be obtained as the entire spiral wound gasket.

The forming process of such a spiral wound gasket is generally as follows. That is, as shown in FIG. 5, the metal strip 1, the expanded graphite filler 22 and the inorganic filler 21 wound on a spool (not shown) are wound around the winding core 10 a predetermined number of times while being fed from the spool. As a result, the inner circumference forming portion 2A of the filler 2 is formed.
Here, although the supply of the inorganic filler 21 is finished, the metal strip 1 and the expanded graphite filler 22 are fed as they are and wound on the inner circumference forming portion 2A of the filler 2 a predetermined number of times to form the outer circumference forming portion of the filler 2. Form 2B.

In the spiral wound gasket constructed as described above, the inorganic filler 21 forming the inner periphery forming portion 2A of the filler 2 and the metal strip plate 1 ensure the necessary compression rigidity and the restoring property, and the spiral wound gasket is obtained. It retains its form as a shape gasket. That is, as a result, the expanded graphite filler 22 forming the outer peripheral formation portion 2B of the filler 2 always holds the required shape. Therefore, when the spiral wound gasket is sandwiched between the flanges A1 and B1 of the pipe A and the pipe B to seal the connecting portion of the pipes A and B as shown in FIG. 6, for example, Even if the tightening of the bolt C becomes too strong, the shape of the expanded graphite filler 22 is not deteriorated by buckling, and the heat resistance and sealing performance of the expanded graphite filler 22 are utilized to exert a reliable sealing ability.

At the same time, the volumetric content of the outer peripheral portion 2B, that is, the expanded graphite filler 22 is 70% or less of the entire filler 2. This is because when the volume content of the expanded graphite filler 22 exceeds 70%, sufficient compression rigidity cannot be obtained as the entire spiral wound gasket even if the other parts of the filler 2 are made of the above-mentioned inorganic material. This is because. Also, the sealing fluid is, for example, 6
In the case of an oxidizing gas of 00 ° C., the inorganic filler 21 can prevent leakage from the inner peripheral side to the outer peripheral side, and can suppress oxidation of the expanded graphite filler 22 to prevent its deterioration.

In particular, in the above spiral forming process, the expanded graphite filler 22 can be shared by the inner peripheral forming portion 2A and the outer peripheral forming portion 2B, so that the metal strip 1, the inorganic filler 21 and the expanded graphite filler 22 are combined. If the wound supply spool is prepared, the metal strip 1 and the expanded graphite filler 22 can be continuously fed out after the inner peripheral forming portion 2 is molded to form the outer peripheral forming portion 2B. In other words, it is not necessary to replace the supply spool on the way, and the molding processing time can be shortened.

Incidentally, D in the figure is a metal outer ring which is fitted on the spiral wound gasket and contributes to maintain its shape.

Next, an embodiment of the spiral wound gasket according to the present invention shown in FIGS. 1 and 2, and a comparative product 1 using only expanded graphite filler 22 as filler 2 as shown in FIG.
Further, as shown in FIG. 4, the compression / restoration test result and the sealing test result of the comparative product 2 in which the inner periphery forming portion 2A of the filler 2 is composed of the inorganic filler 21 and the outer periphery forming portion 2B is composed of the expanded graphite filler 22 are shown. Show.

In the embodiment of the present invention, the compounding ratio and compounding ratio of the inorganic filler 21 in the inner peripheral portion 2A of the filler 2 are as shown in FIG. 9, and the expanded graphite filler 22 is as shown in FIG. Is. In this case, the thickness of the inorganic filler 21 and the expanded graphite filler 22 of the inner periphery forming portion 2A of the filler 2 is 0.4 mm, and the bulk density is 0.7.
g / cm ^3, the coefficient of friction between the flange A, B is 0.26. The expanded graphite filler 22 in the outer peripheral portion 2B of the filler 2 has a thickness of 0.4 mm and a bulk density of 1.1 g / c.
m is ^3.

The blend and blending ratio of the filler (expanded graphite filler) of Comparative Product 1 are also shown in FIG. 10, and further, the blend and blending ratio of the inorganic filler 21 and expanded graphite filler 22 of Comparative Product 2 are shown. Are as shown in FIGS. 9 and 10, respectively.

The following compression / restoration tests were carried out using the above-exemplified product, comparative product 1 and comparative product 2.
FIG. 7 is a front view showing a compression / decompression test device, and M is a test sample such as an implementation product or comparative products 1 and 2. The sample M is set in the hydraulic press P while being sandwiched between the two flanges F, F, and a tightening force can be applied. G is a dial gauge for measuring the compression amount and the restoration amount. Using such a test device, the tightening surface pressure 35
Holds 0 kgf / cm ² and 1000 kgf / cm ² for 1 min each while applying, after which shows a compressive deformation rate of each sample was measured with a dial gauge G in FIG. 11. Further, in FIG. 11, the tightening surface pressure is 1000 kgf / cm ²
The recovery rate of each sample after applying the pressure and the change in inner diameter of each sample (spiral wound gasket) measured with a caliper before and after the test and the amount of deformation are shown together.

As is clear from the results shown in FIG. 11, the product of the present invention has a tightening surface pressure of 350 kgf / c corresponding to the Y value shown in "Structure of JIS8243 Pressure Vessel".
In m ² , the compression ratio is equal to that of the comparative product 2 and smaller than that of the comparative product 1. Then, the tightening surface pressure 10 which can be called an abnormal pressure
At 00 kgf / cm ² , the compressibility of Comparative product 1 and the amount of deformation of the gasket inner diameter are large, and buckling occurs, whereas the compressibility of the product of the present invention is as high as that of Comparative product 2. Remarkably small. Further, the restoration rate at the tightening surface pressure of 1000 kgf / cm ² is much larger than that of the comparative product 1 and slightly larger than that of the comparative product 2. Further, the variation of the inner diameter of each sample before and after the test is as small as the comparative product 2 in the product of the present invention. That is, in the product of the present invention, the inorganic filler 21 of the inner circumference forming portion 2A is rich in compression rigidity and has a large friction coefficient, and thus 1000 kgf / cm.
When subjected to unusually large clamping surface pressure of ² also, it can be seen that buckling hardly occurs as compared with the comparative products 1.

FIG. 8 is a block diagram showing a sealing test device, in which F is a flange, S is a tightening bolt,
A nut, PM is a pressure gauge, V is a valve, and WP is a hydraulic pump. Then, using the tightening bolts and nuts S, the sample M
After being tightened at a tightening surface pressure of 350 kgf / cm ² , the water sent from the water pressure pump WP is sent to the inner peripheral side of the sample M through an inlet passage F1 provided through the lower flange F, A pressure is applied to the sample M. For the tightening bolt / nut S, the relationship between the tightening torque and the generated bolt axial force is measured in advance.

Using the apparatus of FIG. 8 as described above, the embodied products and the comparative products 1 and 2 were heated in an electric furnace before heating and at 350 ° C. for 24 hours, and then subjected to a sealing test after being naturally cooled. . The result is shown in FIG.

As is clear from the results shown in FIG. 12, each sample could be sealed at 140 kgf / cm ² before heating, but the product of the present invention uses only the expanded graphite filler 22 as the filler. Similar to the comparative product 1 which had been used, a remarkably high sealing ability is maintained after heating. This is because, even in a high temperature atmosphere, the inorganic filler 21 of the inner circumference forming portion 2A maintains its shape and the amount of heat loss is small, so that the heat resistance of the expanded graphite filler 22 of the outer circumference forming portion 2B can be effectively utilized. To be done.

Note that the characteristic a of the airtight leakage gas test result of the product of the present invention is compared with the characteristic b of the comparative product 2 and FIG.
Shown in. It has been found that the product of the present invention has characteristics equivalent to those of the comparative product 2. Further, the results of the water pressure resistance test of the product of the present invention at room temperature and at heating are shown in FIG. 14 in comparison with the test results of Comparative product 2 and asbestos-using product (reference product).
It was found that the product of the present invention can exhibit superior water pressure resistance performance than the conventional product.

As described above, in the product of the present invention, the time required for vortex forming can be shortened, and in the strength when an excessive tightening surface pressure is applied, the comparative product 1 using only the expanded graphite filler 22 is used. It is significantly higher than that of Comparative Products 2 using the inorganic filler 21 and the expanded graphite filler 22, and the sealing ability after heating for a long time is as high as that of Comparative Products 1 and 2. It can be seen that it has performance.

The same effect can be expected not only in the above-mentioned embodiment but also in other spiral wound gaskets according to the present invention.

[0039]

As is apparent from the above description, the spiral wound gasket according to the present invention not only obtains excellent sealing performance and heat resistance equivalent to those using the expanded graphite filler, but also has an abnormal It is possible to improve the strength such that buckling does not easily occur even when the tightening pressure is applied, and in particular, compared with the one in which the inner peripheral portion of the filler is composed of an inorganic filler and the outer peripheral portion thereof is composed of an expanded graphite filler, a vortex coil The present invention has an effect that it is easy to form the shape, and the forming time can be shortened to improve the productivity.

[Brief description of drawings]

FIG. 1 is a front view of a spiral wound gasket according to an embodiment of the present invention.

FIG. 2 is a sectional view of the spiral wound gasket.

FIG. 3 is a sectional view of a gasket of Comparative product 1.

FIG. 4 is a cross-sectional view of a gasket of comparative product 2.

FIG. 5 is an explanatory view of a spiral winding process of the spiral wound gasket of the present invention.

FIG. 6 is an explanatory view of a usage state of the spiral wound gasket.

FIG. 7 is a front view of a compression / decompression test device.

FIG. 8 is a front view of the sealing test device.

FIG. 9 is a chart showing the blending of an inorganic filler.

FIG. 10 is a chart showing the composition of expanded graphite filler.

FIG. 11 is a chart showing compression / decompression test results.

FIG. 12 is a chart showing a sealing test result.

FIG. 13 is a characteristic diagram showing an airtight leak test result.

FIG. 14 is a diagram showing results of a water pressure resistance test at room temperature and at the time of heating.

FIG. 15 is an explanatory diagram of a spiral forming process of comparative product 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal strip 2 Filler 2A Inner circumference forming part 2B Outer circumference forming part 21 Inorganic filler 22 Expanded graphite filler

Front page continuation (72) Inventor Takeshi Miyoshi 1 at 541, Shimuchi Shinji-jiba, Mita-shi, Hyogo Pref. Mita Plant of Japan Pillar Industry Co., Ltd. (56) Reference JP-A-1-224571 (JP, A) Actual Open 60-114371 (JP, U) Actual 52-143567 (JP, U)

Claims (1)

[Claims] 1. A spiral wound gasket in which a filler is held in a spiral shape by a metal strip having a corrugated cross section, wherein an inner circumference forming portion of the filler held in the spiral shape is made of an inorganic material excluding asbestos. A spiral wound gasket comprising an inorganic filler as a base material and an expanded graphite filler which is wound around the inorganic filler, and an outer peripheral portion of the filler is formed of the expanded graphite filler.