JP2010159852A - Serrated metal gasket and combination gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Kammprofile gasket having an extremely good sealing performance in a low surface pressure and a serrated metal gasket using the Kammprofile gasket. <P>SOLUTION: The serrated metal gasket and the combination gasket obtained by applying elastic sheets on the both sides of the serrated metal gasket satisfy the conditions that (A) the width w (mm) of the tip of a tooth is 0.2 to 0.90, (B) a value w/p obtained by dividing the width w (mm) of the tip of the tooth by the pitch p (mm) of grooves formed between teeth is 0.15 to 0.45, and (C) w/p<dp/2, where w and p are as described above and d is the depth (mm) of the groove. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a metal sawtooth gasket and a combination gasket generally called a can profile in which an elastic sheet is bonded to both surfaces thereof.

  The can profile gasket was developed by Kempen in Germany in 1970 and has a structure in which an elastic sheet such as expanded graphite is bonded to both sides of a metal sawtooth gasket. It is known as a gasket that can be sealed with a relatively low clamping surface pressure (UK Patent Application Publication No. 2010417).

  This combination gasket has a saw-toothed cross section with many concentric grooves with different diameters on both sides of the metal body, and has a sawtooth shape. A high surface pressure is generated at the tip of the toothbrush, and an elastic sheet such as expanded graphite is bonded to the surface, so the familiarity with the flange surface is good, and the tip of the tooth is directly flanged. Because it does not come into contact with the flange surface, it does not damage the flange surface. For this reason, since it becomes possible to design the width (radial length) of the combined gasket to be narrow due to the structure, it is optimal as a gasket for equipment such as a heat exchanger having a narrow gasket seat in the flange.

  Numerous studies have been conducted on the shape of the groove in this combination gasket by Kemphen, and the width of the tooth tip is 0.1 mm and the groove-to-groove pitch is 1 mm so as not to damage the flange surface at the groove tip. It is recommended that 0 mm, 1.5 mm, the groove depth be 0.33 mm, 0.63 mm, and the groove angle be 90 ° C. In addition, as the elastic sheet to be bonded, an expanded graphite sheet or a tetrafluoroethylene resin (PTFE) sheet is usually used.

  Conventionally, when an expanded graphite sheet or a PTFE sheet is used as an elastic sheet body, the expanded graphite flows into the groove portion of the metal concentric circle by tightening, and this repulsive force exhibits excellent sealing performance even at low surface pressure. It was thought.

  However, when this conventional can profile gasket was subjected to an airtight test at a low surface pressure, a minute leak was detected. For this reason, there has been a demand for a can profile gasket that is more excellent in sealing performance than in the past.

  Accordingly, an object of the present invention is to provide a can profile gasket having a very good sealing performance at a low surface pressure and a metal sawtooth gasket used therefor.

  In this situation, the present inventors have conducted extensive studies. As a result, (1) the leak detected in the low surface pressure tightness test is that the air remaining inside the expanded graphite sheet is compressed and extruded. (2) If the groove volume is increased relative to the expanded graphite volume and a high contact pressure is applied only to the tooth tip width part, the gap inside the expanded graphite in the high contact pressure part is completely filled and tightened. (3) The excellent sealability is such that the width (w) of the tooth tip is within a predetermined range, and the sealability can be improved. A value w / p obtained by dividing the width w (mm) of the tip by the pitch p (mm) of the groove formed between the teeth is within a predetermined range, and w / p <dp / 2 (d is the depth of the groove) A can profile gasket using a metal sawtooth gasket that satisfies Found, such as can be, and have completed the present invention.

That is, the present invention provides the following (A) to (C);
(A) The width w (mm) of the tip of the tooth is 0.2-0.90,
(B) The value w / p obtained by dividing the width w (mm) of the tip of the tooth by the pitch p (mm) of the groove formed between the teeth is 0.15 to 0.45,
(C) Provided is a metal sawtooth gasket that satisfies w / p <dp / 2 (wherein w and p are the same as described above, and d represents the depth (mm) of the groove).

  Moreover, this invention provides the combination gasket obtained by bonding an elastic sheet body on both surfaces of the said metal sawtooth-shaped gasket.

  Since the combined gasket of the present invention relatively increases the groove volume with respect to the elastic sheet body and applies a high surface pressure only to the tooth tip width portion, the gap inside the elastic sheet body of the high surface pressure portion is completely eliminated. The air can be completely pushed out at the stage of filling and tightening. For this reason, the sealing performance at a low surface pressure is very good. Since the conventional combination gasket has a relatively small groove volume with respect to the elastic sheet body, the load is distributed not only in the tooth tip width portion but also in the groove portion, and the gap cannot be completely filled, and the air in the gap is not filled. It seems that leakage will occur because it is pushed out. The metal sawtooth gasket of the present invention is suitable as a constituent member of the combination gasket.

The top view which fractures | ruptures and shows a part of combination gasket of this Embodiment. The figure seen along the AA line of FIG. The expanded sectional view of a sawtooth part. The figure explaining the deformation | transformation state of the elastic sheet by clamping. The figure which shows the state after the fastening of the combination gasket of FIG. FIG. 6 is a diagram showing cross-sectional shapes of various saw teeth. The top view which fractures | ruptures and shows a part of metal sawtooth-shaped gasket used in FIGS. It is the figure seen along the BB line of FIG. It is the schematic of the testing apparatus for sealing performance evaluation.

  A combination gasket according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view showing a part of the combined gasket of the present example, with a part thereof broken, FIG. 2 is a view taken along line AA in FIG. 1, FIG. 3 is an enlarged end view of a sawtooth portion, FIG. FIG. 5 is a diagram illustrating a deformed state of the elastic sheet by tightening, FIG. 5 is a diagram illustrating a state after the combined gasket of FIG. 2 is tightened, and FIG. 6 is a diagram illustrating various sawtooth end face shapes. 7 is a plan view showing a part of the metal sawtooth gasket used in FIGS. 1 to 5 in a cutaway manner, and FIG. 8 is an end view taken along the line BB of FIG. is there.

  The combination gasket 10 is obtained by bonding the elastic sheet bodies 2 and 2 to both surfaces of a metal tooth-shaped gasket 1. When the gasket 10 is tightened, the elastic sheet 2 flows into a groove formed between the saw teeth, and exhibits excellent sealing performance even at a low surface pressure. Further, since the elastic sheet is bonded to the surface, the familiarity with the flange surface is good, and the tip of the saw tooth does not directly contact the flange, so that the flange surface is not damaged.

As shown in FIGS. 7 and 8, the metal sawtooth gasket 1 has a thickness t ₃ and a ring width W in which teeth 12 and a tooth groove 13 having a sawtooth shape in cross section are formed on both surfaces. It is a ring-shaped product. The saw tooth appears when a plurality of concentric grooves 13 having different diameters are formed at an equal pitch in the radial direction. That is, a groove 13 is formed between adjacent teeth (saw teeth) 12.

  Examples of the material of the metal sawtooth gasket 1 include stainless steel such as stainless steel 316L steel and stainless steel 304 steel, and other alloy steels. The selection of the material is appropriately determined depending on the type and temperature of the fluid used.

  The metal sawtooth gasket 1 has a tooth width w (mm) of 0.2 to 0.90 (configuration (A)). The width w of the tip of the tooth is flat and is in contact with the elastic sheet body 2. Further, after tightening, the elastic sheet body 2 becomes a portion that applies high surface pressure. If the width w of the tooth tip is too narrow, the surface pressure of the tooth tip portion becomes too high and the elastic sheet 2 protrudes into the groove 13, and conversely if the width w of the tooth tip is too wide, the sealing property The surface pressure is not sufficient to maintain the pressure.

  Further, in the metal sawtooth gasket 1, the value w / p obtained by dividing the width w (mm) of the tip of the tooth by the pitch p (mm) of the groove is 0.15 to 0.45 (Configuration (B)). ). If the w / p value is too high, the surface pressure at the tip of the tooth will be too low to maintain the sealing performance. If the w / p value is too low, the surface pressure at the tip of the tooth will become too high and elasticity will be generated. The sheet body 2 protrudes into the groove 13.

  The metal toothed gasket 1 has w / p <d × p / 2 (where w and p are the same as described above, and d indicates the depth (mm) of the groove formed between the teeth. (Configuration (C)). The right side of this inequality expression is half of the product of the groove pitch p and the groove depth d, and is approximately equal to the cross-sectional area of the groove 13. Therefore, if this inequality is not satisfied, that is, if the cross-sectional area of the groove 13 is too small, the elastic sheet immediately fills the groove before the density of the elastic sheet at the tip width w of the tooth becomes sufficiently high. As a result, the load is dispersed not only in the elastic sheet body in the tooth tip width w portion but also in the groove 13 portion, and the density of the elastic sheet body 2 in the tooth width w portion is not increased. , Can not exhibit excellent sealing performance. On the other hand, if the cross-sectional area of the groove 13 is large, the amount of the elastic sheet body 3 that can flow into the groove 13 is large even if w / p is large, so that the load is not distributed to the elastic sheet body in the groove 13 portion. The density of only the elastic sheet at the tip width w portion of the teeth is increased, and excellent sealing performance can be exhibited.

  The shape of the sawtooth and the groove in the metal sawtooth gasket 1 is not particularly limited as long as the tip of the sawtooth is a flat surface, the sawtooth has a trapezoidal cross section, and the groove has a reverse trapezoidal cross section. (FIG. 6 (A)), a groove having a concave and arc-shaped cross section (FIG. 6 (B)), a sawtooth having a trapezoidal cross section, and a groove having a substantially V-shaped cross section having a groove angle of 90 to 130 degrees. ((FIG. 6C)) and the like.

  The metal sawtooth gasket 1 may have a groove 4 for fitting the outer ring 5 on its outer peripheral surface (side surface). The outer ring 5 is used for the purpose of centering in accordance with the position of the bolt when the combination gasket 10 is aligned with the bearing surface of the flange. Examples of the material of the outer ring 5 include stainless steel such as 304 steel and 430 steel, and carbon steel. Further, the outer ring 5 may be formed such that a notch for facilitating fitting into the metal sawtooth gasket 1 extends in the radial direction. Further, the end faces of the outer ring 5 divided into two can be used by welding.

  In the combination gasket 10, if the metal sawtooth gasket 1 satisfying the above-described configurations (A) to (C) is used, the sealing performance is remarkably improved even when the tightening force is relatively low. This is because, when the above configurations (A) to (C) are satisfied, a part of the elastic sheet body 2 around the tip of the saw tooth 11 flows into the groove 13, and the width (w) portion of the tip of the saw tooth 11 This is because the surface pressure applied to the moderately left elastic sheet body 2 increases (density increases). This action of the present invention is completely different from the idea that the sealing property that has been said so far is the repulsive force of the elastic sheet body 2 flowing into the groove.

  Examples of the elastic sheet 2 used in the combination gasket 10 include an expanded graphite sheet, a PTFE (tetrafluoroethylene resin) sheet, an aluminum sheet, a silver sheet, a copper sheet, and a fiber reinforced rubber sheet. Among these, when the expanded graphite sheet and the PTFE sheet are used in combination with the metal sawtooth gasket 1 satisfying the above-described configurations (A) to (C), the elastic sheet body 2 around the tip of the sawtooth 11 is used. Part of the groove 13 flows into the groove 13 and the effect of increasing the surface pressure (increasing density) exerted on the elastic sheet 2 that is left in the width (w) portion of the tip of the saw tooth 11 is remarkably exhibited. It is suitable. Moreover, since the PTFE sheet has excellent chemical resistance, it is suitable for use in a site that requires chemical resistance.

  The elastic sheet body 2 is usually attached to the metal sawtooth gasket 1 with an adhesive. Therefore, an adhesive layer is present between the tooth tips of the metal toothed gasket 1 and the elastic sheet body 2. The elastic sheet body 2 has a thickness of 0.2 to 1.2 mm, preferably 0.25 to 1.0 mm. If the thickness of the elastic sheet body 2 is too thin, the thickness of the elastic sheet 2 at the upper end of the tooth after flowing into the groove 13 cannot be secured, and the effect of the present invention is not achieved. The elastic sheet 2 can be the same as a known gasket sheet. The adhesive may be a known one, and for example, an SBR adhesive can be used. The metal sawtooth gasket 1 and the elastic sheet body 2 may be bonded by an adhesive means such as a double-sided tape in addition to the adhesive.

  Next, an example of a method for manufacturing the combination gasket 10 will be described. The combination gasket 10 is, for example, an I process in which a plate-shaped stainless steel plate having a predetermined thickness of 3.0 mm is processed into a ring shape so as to have a predetermined gasket size, and a ring having a predetermined thickness obtained in the I process. A plurality of concentric grooves 13 having different diameters are cut with a lathe so as to satisfy the above-described configurations (A) to (C) with respect to both sides (flat surfaces) of the object. Then, punching is performed so that the same size is obtained from an elastic sheet having a predetermined thickness on both sides of the metal sawtooth gasket obtained in Step II and Step II to obtain a metal sawtooth gasket (intermediate). The obtained ring-shaped elastic sheet is attached with an adhesive, and is obtained by carrying out step III to obtain a combined gasket.

  In the step I, as a method of processing a plate-shaped stainless steel plate into a ring shape, in addition to the above-described laser processing, for example, a band-shaped metal may be formed into a circular shape by bending and end faces may be welded. Bending is effective when producing a large metal sawtooth gasket. Further, after the step I, a groove for fitting the outer ring may be formed on the ring-shaped outer peripheral surface.

  The shape and action of the metal sawtooth gasket obtained in step II are the same as those of the metal sawtooth gasket, and the description thereof is omitted. Further, the metal sawtooth gasket obtained in the step II is the metal sawtooth gasket of the present invention.

  The elastic sheet used in step III is the same as the elastic sheet described in the combination gasket, and the description thereof is omitted.

  The metal sawtooth gasket of the present invention is a metal sawtooth gasket used in the combination gasket, and is similar to the description of the metal sawtooth gasket in the combination gasket and the manufacturing method thereof. Is omitted. That is, the metal sawtooth gasket of the present invention is suitably used for a combination gasket, and serves as an intermediate in the manufacturing process of the combination gasket. Further, the metal sawtooth gasket of the present invention is not used as it is between the flanges.

The combined gasket of the present invention is used, for example, as a gasket for joints of pipes in oil refineries / petrochemical plants, power plants and steelworks, or a gasket for preventing leakage for equipment such as heat exchangers. Even if the tightening force is relatively weak, it exhibits excellent sealing performance. It is sufficient if the tightening force, that is, the gasket surface pressure is 39.2 to 78.5 N / mm ² , preferably 39.2 N / mm ² .

(Example)
EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

  A plate-shaped stainless steel 316L steel having a thickness of 3.0 mm was subjected to laser processing so that a ring-shaped product having an inner diameter of 98.4 mm and an outer diameter of 123.8 mm was obtained. Next, the both sides were cut by a lathe so as to have the tooth and groove shapes shown in Example 1 of Table 1, and a metal sawtooth gasket was produced. The cross-sectional shape of the groove was substantially V-shaped. Further, a groove for the outer ring was processed so that the outer peripheral surface of the ring-shaped object had a groove depth of 1.1 mm and a groove width of 1.3 mm. Next, a ring-shaped outer ring made of stainless steel 304 having a thickness of 1 mm and fitted into the groove for the outer ring was produced. The ring-shaped outer ring was cut in a radial direction at one place so as to be easily fitted, and thereafter, the groove for the outer ring was fitted and the end surfaces of the cut portions were joined by welding. Next, a ring-shaped material punched out from expanded graphite having a thickness of 0.5 mm to the same size was attached to both surfaces of a metal sawtooth gasket with an SBR adhesive to produce a combined gasket. About the obtained combination gasket, the sealing property was evaluated by the following method. The results are shown in Table 1.

(Evaluation of sealing performance)
The sealability was measured with a test apparatus shown in FIG. That is, the combination gasket (test body) 21 is sandwiched between the upper and lower flanges 24, 24, the collecting outer cylinder 25 is attached, and tightened so that the gasket surface pressure is 58.8 N / mm ² . Then, the test port formed in the collection outer cylinder 25 and the helium leak detector 22 are connected, and the inside of the mass spectrometer (not shown) installed in the helium leak detector is evacuated. Next, helium gas with an internal pressure of 2.1 MPa is loaded into the combination gasket (test body) 21 and leakage is measured. Reference numeral 23 denotes a helium cylinder, and reference numeral 26 denotes an O-ring.

Examples 2-4, Comparative Examples 1-7
A combined gasket was produced in the same manner as in Example 1 except that the groove shape shown in Table 1 was used. About the obtained combination gasket, the sealing performance was evaluated by the same method as in Example 1. The results are shown in Table 1.

As is apparent from Table 1, in the examples satisfying the requirements of the configurations (A) to (C), the leakage amount is 1.1 × 10 ^{−11 to} 1.5 × 10 ⁻⁷ Pam ³ / s, that is, approximately 10 ^The comparative example, which is smaller than ⁻⁷ Pam ³ / s and has all or part of the requirements of the configurations (A) to (C), has a leakage amount of 1.3 × 10 ^{−5 to} 1.0 × 10 ^−4. Pam ³ / s, that is, generally greater than 10 ⁻⁴ Pam ³ / s. Thus, the combination gasket of the present invention can remarkably suppress the leakage amount by satisfying the configurations (A) to (C).

  The combined gasket of the present invention exhibits extremely excellent sealing performance even with a relatively weak tightening force, so it can be used as a gasket for piping joints in oil refining / petrochemical plants, power plants and steelworks, or heat exchange. It is suitable as a gasket for preventing leakage of equipment such as a vessel.

1 Metal sawtooth gasket 2 Elastic sheet 10 Combination gasket 12 Teeth (this tooth)
13 Grooves formed between teeth

UK Patent Application Publication No. 2010417 and FIGS.

Claims (3)

The following (A) to (C);
(A) The width w (mm) of the tip of the tooth is 0.2-0.90,
(B) The value w / p obtained by dividing the width w (mm) of the tip of the tooth by the pitch p (mm) of the groove formed between the teeth is 0.15 to 0.45,
(C) A metal sawtooth gasket characterized by satisfying w / p <dp / 2 (wherein w and p are the same as described above, and d represents the depth (mm) of the groove).   A combination gasket obtained by bonding an elastic sheet on both sides of the metal sawtooth gasket according to claim 1.   The combination gasket according to claim 2, wherein the elastic sheet body is an expanded graphite sheet or a PTFE sheet.

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