JPH0678797B2 - Insulation fitting - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an insulating joint.

[Conventional technology]

As described in Japanese Patent Laid-Open No. 56-46190, a conventional insulating joint structure as shown in FIG. 4 is used. As shown in the figure, the piping member 1 is provided with a flange 2 at each end thereof. An annular ceramic member 3 is interposed between the adjacent flanges 2 and tightened with an insulating bolt 4 and a nut 5. Are combined. The sealing of this joint is performed as follows. Base metal 6 is silver brazed on both side wall surfaces of the annular ceramic member 3, and metallic O-rings 7 are respectively arranged between the flange 6 and the thickened portion 6a.
Further, the insulating member 8 is also installed between the thick portions 6a of the base metal.

[Problems to be solved by the invention]

In the above-mentioned prior art, since a metallic O-ring having a very large tightening force is used, in order to prevent the annular ceramic member from being broken, the base metal portion should be prevented from being directly applied to the annular ceramic member. Tightening is performed, and there is an advantage in preventing gas leakage due to breakage of the annular ceramic member. However, when used in a high temperature gas atmosphere of around 650 ° C, a bolt loosening phenomenon or conversely an overtightening phenomenon may occur due to an imbalance in the difference in expansion due to thermal expansion of each piece made of metal material, so-called thermal expansion difference. In the former case, gas leakage was caused by a decrease in tightening pressure, and in the latter case, overstress occurred in each piece, resulting in breakage and deformation, resulting in a short life. In addition, the silver brazing part has a decrease in its welding strength at a temperature close to the brazing temperature (650 ° C), and an oxide film formed between the base metal and the welding part (especially for Kovar used as a base metal) There is a problem that the cyclic ceramics member falls off due to the strong oxidation). Further, since it has a double insulating structure of an annular ceramic member and an insulating member, it has a very complicated structure, and there is a problem that assembly is very difficult.

As described above, the prior art does not take into consideration the imbalance in the thermal expansion difference between the respective parts when used at high temperatures (around 650 ° C.), and gas leaks and fracture deformation of the respective parts occur. Further, the structure is complicated, and there are problems such as difficulty in assembling and high price due to an increase in the number of parts.

The present invention has been made in view of the above points, and an object of the present invention is to provide an insulating joint capable of obtaining stable sealability during high temperature use.

[Means for solving problems]

The object is to form the gasket with a metallic hollow O-ring, and for the insulating bolt, the flange and the annular ceramic member, the amount of expansion due to the thermal expansion of the insulating bolt is equal to or less than the total amount of the thermal expansion of the flange and the annular ceramic member. By forming the material with
To be achieved.

[Action]

Since the gasket is formed of the metallic hollow O-ring, the tightening pressure can be small. Since the insulating bolts, flanges and annular ceramic members are made of a material such that the amount of expansion due to thermal expansion of the insulating bolts is less than or equal to the total amount of expansion due to thermal expansion of the flanges and annular ceramic members, the amount of thermal expansion of the insulating bolts Is formed so as to be less than or equal to the total amount of thermal elongation of the flange and the annular ceramic member, and a tensile force acts on the insulating bolt. Therefore, the tensile force of the insulating bolt always acts on the metallic hollow O-ring, which requires only a small tightening pressure at high temperature, so that the metallic hollow O-ring retains a constant tightening pressure required for gas sealing. Will be able to
It is possible to obtain a stable sealing property when used at high temperature.

〔Example〕

Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 shows an embodiment of the present invention. Since the same parts as those of the prior art are designated by the same reference numerals, the description thereof will be omitted. In the present embodiment, the gasket is formed of the metallic hollow O-ring 9, and the insulating bolt 4, the flange 2 and the annular ceramic member 3 have the thermal expansion amounts of the insulating bolt 4 and the flange 2 and the annular ceramic member 3, respectively. Is formed of a material that is less than or equal to the total. By doing so, the gasket is formed by the metallic hollow O-ring 9, and the insulating bolt 4, the flange 2 and the annular ceramic member 3 have the thermal expansion amount of the insulating bolt 4 which is equal to that of the flange 2.
And to make the metallic hollow O-ring 9 maintain a constant tightening pressure required for gas sealing at high temperatures by being formed of a material whose total thermal expansion of the annular ceramic member 3 is less than or equal to the total. As a result, it is possible to obtain an insulating joint that makes it possible to obtain stable sealing properties when used at high temperatures.

That is, the metallic hollow O-ring 9 is arranged between the side walls of the annular ceramic member 3 and the flange 2 in contact therewith. The insulating bolt 4 and the nut 5 are fastened via the washer 10, but the insulating bolt 4 is provided with a ceramic member 11 between the flange 2 and the insulating bolt 4 on one side thereof so as to have an insulating property. Insulation as a ring ceramic member 3
It is done together with. Insulation bolt 4, flange 2
The annular ceramic member 3 is formed of a material such that the thermal expansion of the insulating bolt 4 is equal to or less than the total thermal expansion of the flange 2 and the annular ceramic member 3, but this material, that is, high temperature (around 650 ° C) Martensitic stainless steel was used for the insulating bolt 4, austenitic stainless steel for the flange 2, and alumina ceramic for the annular ceramic member 3 as materials that can be used in terms of material strength during use. The difference in thermal expansion between the insulating bolt 4 and the flange 2 and the annular ceramics member 3 required at the time of use at high temperature is set to satisfy the relationship shown in FIG. In the figure, the vertical axis shows the amount of thermal expansion and the horizontal axis shows the temperature.
_The change characteristics of _B and the thermal expansion amount λ _{F in the} pipe direction of the flange-tenth annular ceramic member with temperature are shown. The difference Δλ at 650 ° C. between the thermal expansion amount λ _{B in} the insulating bolt piping direction and the thermal expansion amount λ _{F in} the flange ten-ring ceramics member piping direction was set to 0 or more, which is necessary to prevent the loosening of the insulating bolt. The upper limit of Δλ is (1) the stress value of each part generated by the difference in thermal expansion necessary for the determination,
(2) Determined from the restoration amount of the metallic hollow O-ring. That is, FIG. 3 shows the change characteristics of the stresses σ _B , σ _F , and σ _S of insulating bolts, flanges, and annular ceramics members with temperature, with the stress on the vertical axis and the temperature on the horizontal axis. The upper limit of is from (1) to insulation bolt stress σ _B ,
Flange stress sigma _F must decide to transition respectively the insulating bolt material allowable stress sigma _B0, the following flange material allowable stress sigma _B0. By the way, in this embodiment, since the metallic hollow O-ring having a very small initial tightening pressure was used,
Bolt flange generated stress 15~17kg / mm ^2, it is possible to suppress the degree annular ceramics member generated stress 2-3 kg / mm ^2, as shown in the figure, the insulating bolts stress σ
_B , Flange stress σ _F , Annular ceramic member stress σ
The _S, respectively the insulating bolt material allowable stress sigma _B0, flange material allowable stress sigma _S0, it is possible to transition to the following ceramics allowable stress sigma _S0, destruction of these sections, the deformation is prevented. Further, the metallic hollow O-ring is deformed by Δλ by the restoration amount, and a gap is generated when the operating temperature is returned from 650 ° C. to normal temperature.
Is determined within the restoration amount of the metallic hollow O-ring, the metallic hollow O-ring can be made to follow the gap, and the gas sealability can be prevented from deteriorating.

As described above, according to this embodiment, it is possible to prevent the insulating bolt, the flange, and the annular ceramic member from being deformed or broken even when used at a high temperature of 650 ° C., and obtain a stable sealing property. Also, it has excellent heat cycle properties, and can be made into a compact and detachable insulating joint.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a stable sealing property at the time of using at a high temperature, and it is possible to obtain an insulating joint which makes it possible to obtain a stable sealing property at the time of using a high temperature.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view of an embodiment of the insulating joint of the present invention, FIG. 2 is a characteristic diagram showing changes in the thermal expansion amount of insulating bolts and flanges 10 ring plastics members with temperature, and FIG. 3 is insulating bolts and flanges. FIG. 4 is a vertical sectional side view of a conventional insulating joint, which shows a change characteristic of the stress of the annular ceramic member with temperature. 1 ... Piping member, 2 ... Flange, 3 ... Annular ceramic member, 4 ... Insulation bolt, 9 ... Metallic hollow O-ring.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazushi Otsuka 3-1-1, Sachimachi, Hitachi, Ibaraki Hitachi Ltd. Hitachi factory Hitachi (72) Inventor, Tsutomu Takahashi 3-chome, Hitachi, Hitachi No. 1 No. 1 in Hitachi Works, Hitachi Ltd. (56) References JP-A-56-46190 (JP, A)

Claims (4)

[Claims] 1. Between flanges of piping members arranged to face each other,
An insulating joint in which an annular ceramic member and a flange in which a gasket is provided in parallel is tightened with an insulating bolt. In the insulating joint, the gasket is formed of a metallic hollow O-ring, and the insulating bolt, the flange and the annular ceramic member are also provided. Is formed of a material such that the amount of expansion due to thermal expansion of the insulating bolt is equal to or less than the total amount of expansion due to thermal expansion of the flange and the annular ceramics member. 2. The insulating joint according to claim 1, wherein the insulating bolt is made of martensitic stainless steel. 3. The insulating joint according to claim 1, wherein the flange is made of austenitic stainless steel. 4. The insulating joint according to claim 1, wherein the annular ceramic member is made of alumina ceramics.