JPH0432553Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gasket, and more particularly to a gasket in which a spirally wound core is covered with a fluororesin jacket having a U-shaped cross section.

[Conventional technology]

Various gaskets are interposed between the flanges of two connected pipes to prevent fluid leakage, and fluororesin-coated gaskets and spiral-wound gaskets are widely used as these gaskets. . Among these fluororesin-coated gaskets, those in which a core material such as an asbestos joint sheet is covered with a fluororesin molded outer jacket with a U-shaped cross section are:
Creep phenomenon at relatively high temperatures can be prevented, and by making the inner diameter side of the gasket the same diameter as the inner diameter of the pipe, turbulent flow of the internal fluid can be prevented, and fluid retention between the flanges can also be prevented.

On the other hand, a spiral gasket is made by overlapping a metal strip and a cushioning material, winding them in a spiral shape, and fixing the metal strips at the beginning and end of the winding with spot welding, and has high pressure resistance and heat resistance. It also has an excellent leak-proofing effect.

[Problem that the invention attempts to solve]

However, the above-mentioned fluororesin-coated gasket has the problem that if the tightening force is increased, the core material protrudes from the fluororesin molded outer jacket, so it cannot be used for sealing high-temperature, high-pressure fluids. If it is a gas, this gas is
There was also the problem that it penetrated the outer covering and deteriorated the core.

Spiral-wound gaskets also have difficulty sealing high pressure gas fluids with low clamping surface pressures. Furthermore, it is difficult to prevent the fluid from stagnation at the stepped portion where the flange and gasket meet, and for this reason, if the fluid is a resin monomer, it may crystallize and grow due to the polymerization action that accompanies the stagnation. There was a problem when the flow path was narrowed.

As described above, while the fluororesin-coated gasket and the spiral-wound gasket each have excellent features, they each have the above-mentioned drawbacks, which limit their range of use.

Therefore, an object of the present invention is to provide a fluororesin-coated gasket that takes advantage of the advantages of a fluororesin gasket and a spiral-wound gasket while solving the drawbacks of each.

[Means for solving problems]

In order to achieve this objective, the present invention has a spiral core formed by overlapping a metal band and a cushioning material and winding them in a spiral, and coating both end surfaces of the spiral core. The fluorine resin outer ring is characterized by being open on the outer side of the cross section and having a U-shaped inner diameter that is approximately equal to the inner diameter of the pipe. That is.

[Effect]

According to the present invention, when the gasket is tightened, the metal band is inserted into the inner surface of the outer ring and is mechanically connected to the outer ring. Therefore, even if the tightening force increases, the core material will not separate from the outer cover. Furthermore, since the outer ring is made of fluororesin, gas fluid can be sealed with low tightening surface pressure. In addition, by matching the inner diameter of the outer ring to the inner diameter of the flange,
Internal fluid turbulence and stagnation between the flanges is prevented.

〔Example〕

An embodiment of the fluororesin-covered gasket according to the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, a gasket 3 made of fluororesin is interposed between a pair of flanges 1 and 2, and this gasket 3 has a U-shaped cross section that covers a core material 4 and a portion of the core material 4 from the outside. It is composed of an outer cover ring 5 made of fluororesin. The core material 4 is made by overlapping a thin metal band with an M-shaped or V-shaped cross section and a soft band-shaped cushioning material, tightly rolling it into a spiral shape, and spotting the metal bands at the beginning and end of the winding. The structure is fixed by welding. Stainless steel, titanium, monel, etc. are used as the material for this metal band. In addition, asbestos paper and PTFE can be used as cushioning materials.
(tetrafluoroethylene resin), graph oil, etc. are used.

The outer ring 5 made of fluororesin is a ring whose inner diameter D is approximately the same as the inner diameter (inner diameter of the pipe) of the flanges 1 and 2, and its cross section is U-shaped with an outward opening. PTFE is suitable as the material for the outer ring 5 made of fluororesin.

In this embodiment, an outer ring 4 is attached so as to fit around the core material 4. This outer ring 6 enables centering when the flange is attached, and also enables higher pressure fluid sealing. Note that the outer ring 6 is made of a mild steel plate, stainless steel, titanium, or the like.

When the fluororesin-coated gasket 3 constructed in this manner is tightened by crimping the flanges 1 and 2 in FIG. It is mechanically coupled to the ring 5. Therefore, even if the tightening force is increased, the core material 4 is prevented from separating from the outer sheath ring 5. Furthermore, since the inner diameter of the outer sheath ring 5 is set approximately equal to the inner diameter of the flanges 1 and 2, it is possible to prevent turbulence of the internal fluid flowing inside the pipe and to prevent the fluid from stagnation between the flanges 1 and 2. can be prevented.

Figure 2 is a graph showing experimental data for determining the relationship between sealable internal pressure and initial gasket tightening surface pressure (including internal pressure). Compared to Comparative Examples A, B, and C of spiral-wound gaskets, the fluororesin-coated gasket of the embodiment of the present invention shown in FIG. 1 has a lower initial gasket tightening surface pressure, as shown by curve D. . Note that this experiment was conducted at room temperature, and the internal fluid was nitrogen gas.

As exemplified by the above embodiments, since the outer cover 5 is molded from fluororesin, gas fluid can be sealed with a lower tightening surface pressure than with conventional spiral-wound gaskets. Furthermore, the sealing effect is equivalent to or better than that of a conventional fluororesin-coated gasket because the metal band of the core material 4 bites into the inner surfaces of the flanges 5a and 5b of the outer ring 5.

In addition, as shown by the dotted line in FIG.
By interposing the outer ring 6, it is possible to prevent the gasket core material 4 from unwinding in cooperation with the outer ring 6.

[Effects of the invention] As is clear from the above explanation, the fluororesin-coated gasket according to the invention consists of a spiral core formed by overlapping a metal strip and a cushioning material and winding them in a spiral, and It is equipped with a fluororesin outer sheath ring that covers the spiral core from the outside, and this fluororesin outer sheath has a U-shaped cross section with an opening on the outer periphery, so it can be used as a low-pressure tightening surface. Even under pressure, the metal band easily bites into the inner surface of the flange of the outer sheath ring when the gasket is tightened, preventing the core material from coming off, and can also be applied to sealing high-temperature, high-pressure fluids. Furthermore, since the outer cover is made of fluororesin, it is possible to seal the gas fluid with lower tightening surface pressure than with conventional spiral-wound gaskets. Furthermore, since the inner diameter of the outer cover is made to match the inner diameter of the flange, it is possible to prevent turbulence of the internal fluid and also to prevent stagnation between the flanges.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of a fluororesin-coated gasket according to the present invention, and FIG. 2 is a graph showing the relationship between the sealable internal pressure of the gasket and the initial gasket tightening surface pressure. 1, 2...Flange, 3...Fluorine resin molded outer cover, 4...Core material, 5...Outer ring.

Claims (1)

[Claims for Utility Model Registration] 1. A spiral core formed by overlapping a metal band and a cushioning material and winding them in a spiral, and a fluorine material covering both end surfaces of the spiral core. and a resin outer ring, the outer ring made of fluororesin being open on the outer side in cross section and having a U-shaped inner diameter approximately equal to the inner diameter of the pipe. . 2 Claims for registration of a utility model characterized in that an outer ring is arranged on the outside of the spiral core, and a retaining ring is inserted between the inner peripheral surface of the core and the outer link. Gasket according to paragraph 1.