JP2006125608A - Sealing device, and piping using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device for preventing the corrosion due to the electrolytic corrosion, and further to provide the piping using the same. <P>SOLUTION: In the sealing device having a sealing member 10 for sealing the portion between members 5. 6 to be sealed, a member 7 higher than the members 5, 6 to be sealed in an electromotive force series is arranged on the sealing member 10 or in the neighborhood of the sealing member. By this configuration, the sacrifice electrode 7 arranged on the outer periphery side 13 of the sealing member or in the neighborhood of the outer periphery side 13 intensively corrodes. As a result, the electrolytic corrosion of the members 5, 6 to be sealed or the sealing member 10 can be prevented. Further, the check of the leakage of gas, etc. can be surely carried out, and the reliability can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sealing device that seals between members to be sealed, and particularly relates to a sealing device that prevents electric corrosion and piping using the same.

As a member to be sealed, there is a flange portion of a pipe through which a cryogenic fluid such as LNG, liquid hydrogen, liquid nitrogen, liquid oxygen or the like in a fuel facility in an electric power plant or an LNG ship circulates. Between such flange portions, a seal member such as a gasket (spiral wound gasket) is sealed so that cryogenic fluid does not leak from the flange portions.
Generally, a metal material such as carbon steel, steel, cast iron, stainless steel, copper, or an aluminum alloy is used for the flange portion. In the spherical tank 2 of the moth type LNG ship 1 shown in FIG. Has been applied. The spherical tank upper part 2a is provided with a plurality of pipes 3a to 3e made of aluminum alloy as shown in FIG. These pipes 3a to 3e are LNG supply / discharge pipes 3a, gas return pipes 3b, cooling pipes 3c, or pipes 3d through which auxiliary equipment such as pumps and valves are passed, pressure gauges, thermometers, etc. There are provided a plurality of pipes 3e through which the instruments are connected, and a safety valve gas discharge pipe 3f.
Moreover, stainless steel is applied to the piping 4 on the fuel facility side for fire resistance. In such flange portions 5 and 6 for connecting the pipes 3 and 4, when rainwater or the like stays between dissimilar metals, a circuit in which a current flows is formed and electric corrosion proceeds, so-called electric corrosion. There was a problem that occurred.

Therefore, as shown in FIG. 5, in the pipes 3 and 4 through which LNG, liquid hydrogen, etc. circulate, a tightening force is applied by bolts 14 and nuts 15 via the spiral wound gasket 8 between the flange parts 5 and 6. However, in order to prevent static electricity charging due to insulation, it is stipulated by international law that the flange portions 5 and 6 are always energized. For this reason, the spiral wound gasket 8 using the electrically conductive graphite is suitably used as a seal member between the flange portions 5 and 6 of the pipes 3 and 4 in an LNG ship or the like.
The spiral wound gasket 8 includes a gasket main body 11 and an inner ring 12 and an outer ring 13 attached to the gasket main body 11. The gasket body 11 is formed by alternately winding a metal thin strip (hoop) 11a such as aluminum and a cushion material (filler) 11b made of non-metallic material such as graphite or glass seals in a spiral shape. The inner ring 12 is an annular body made of stainless steel, and suppresses deformation of the gasket body 11 inward in the radial direction due to tightening. Similarly, the outer ring 13 is also a stainless steel annular body, and serves to suppress deformation of the gasket main body 11 in the radial direction due to tightening and to suppress deformation in the radial direction due to the internal pressure in the pipe. The spiral wound gasket 8 can obtain a good sealing property at an extremely low temperature through which LNG or the like is distributed.

However, rainwater, seawater or the like enters and stays in the gap 9 formed between the flange portions 5 and 6 of the pipes 3 and 4 and the outer ring 13, and the outer ring 13 and / or the flange portions 5 and 6 are electrically corroded. There was a problem of corrosion.
As means for solving such a problem, for example, a spiral wound gasket in which a gap is completely sealed with a soft material as shown in Patent Document 1 is known. Patent Document 1 describes a spiral wound gasket in which a soft member that fills a gap between the outer ring and the flange portion of the gasket is disposed. By eliminating the gap in the soft member, rainwater, seawater, etc. By preventing intrusion and retention, corrosion of the flange portion or gasket due to electric corrosion is prevented.

JP-A-9-329278

However, if the gap between the flange portion and the gasket portion is completely filled with a soft member, even if gas leaks due to deterioration of the gasket, it is sealed with the soft member, so that gas leakage from the gasket cannot be detected. There's a problem.
Furthermore, due to aging of the soft member, rainwater, seawater, etc. may invade and stay inside the soft member, causing electric corrosion.

  In view of such problems, an object of the present invention is to provide a sealing device that prevents corrosion due to electric corrosion, and a pipe using the same.

  In order to solve the above-described problems, a sealing device according to the present invention is a sealing device including a sealing member that seals between sealed members. A member is arranged.

  According to the present invention, by disposing a member having a higher potential row than the member to be sealed in the vicinity of the sealing member or the sealing member, the members having a higher potential row are concentrated and corroded due to electrical corrosion caused by rainwater, seawater, or the like. . As described above, by using a member having a high potential row as the sacrificial electrode, it is possible to prevent electric corrosion of the member to be sealed or the sealing member. Note that the member having a high potential row as the sacrificial electrode may be disposed separately in the vicinity of the seal member, or may be disposed integrally with the seal member.

  In the sealing device according to the present invention, the member having a high potential row is a metal having a higher potential row in seawater than an aluminum alloy.

  According to the present invention, among the materials generally used for a member to be sealed, a metal having a potential row higher than that of a high-luminum alloy in the seawater is disposed near the seal member or the seal member. Corroded intensively as an electrode. Thereby, the electrical corrosion of the member to be sealed or the sealing member can be prevented. Further, using a sacrificial electrode made of a metal having a high potential sequence in seawater is advantageous in preventing electrical corrosion of the member to be sealed, particularly in a ship exposed to seawater.

  In the sealing device according to the present invention, the metal having a higher potential series in seawater than the aluminum alloy is cadmium, aluminum, zinc, a magnesium alloy, or magnesium.

  According to the present invention, since cadmium, aluminum, zinc, magnesium alloy, or magnesium is disposed in the vicinity of the sealing member or the sealing member, the sacrificial electrode is corroded intensively. Can be prevented. In particular, by using zinc as the sacrificial electrode, the sealing device can be manufactured at low cost.

  In the sealing device according to the present invention, the member having a high potential row is arranged on the outer peripheral side.

  According to the present invention, by arranging a member having a high potential row on the outer peripheral side of the seal member in which seawater or rainwater invades and stays and is likely to cause electrical corrosion, corrosion is concentrated as a sacrificial electrode. Thereby, the electrical corrosion of the member to be sealed or the sealing member can be prevented.

  Further, in the sealing device according to the present invention, the seal member seals between the members to be sealed, and a gasket body formed by alternately winding a metal hoop and a non-metallic material filler in a spiral shape; In the spiral wound gasket constituted by the inner ring provided inside the gasket body and the outer ring provided outside the gasket body, the outer ring is provided with a metal having a high potential row. And

  According to the present invention, since the metal having a high potential row is provided on the outer ring of the spiral wound gasket, which is likely to cause electric corrosion, the metal having the high potential row is intensively corroded as a sacrificial electrode, thereby preventing the electrical corrosion of the flange portion. be able to. According to this, a sealing device excellent in corrosion resistance can be obtained, and the reliability of the sealing device can be improved.

  In the sealing device according to the present invention, the member having a high potential row is arranged on the outer peripheral side of the sealing member by plating.

  According to the present invention, the sacrificial electrode can be easily arranged on the outer peripheral side of the seal member by arranging the member having a high potential row by plating. Thereby, the sacrificial electrode arrange | positioned on the outer peripheral side of a sealing member is corroded intensively, and the electric corrosion of a to-be-sealed member or a sealing member can be prevented. In addition, since the sacrificial electrode is disposed on the outer peripheral side of the seal member by plating, it is possible to easily check the consumption of the sacrificial electrode and to easily check for gas leakage and the like. Thereby, the maintainability of the sealing device is improved.

  According to the sealing device of the present invention and piping using the same, it is possible to prevent electrical corrosion of the member to be sealed or the sealing member. Further, maintenance can be easily performed.

  Below, the structure of the spiral wound gasket (seal member) concerning embodiment of this invention is demonstrated with reference to drawings. In addition to the configuration of the conventional spiral wound gasket, a member (sacrificial electrode) having a higher potential column than the flange portion (sealed material) is disposed in the vicinity of the spiral wound gasket or the spiral wound gasket. In addition, the same code | symbol is attached | subjected about the structure same as the past.

  FIG. 1 shows only one side portion with respect to the center line of the longitudinal sectional view of the spiral wound gasket (seal member) 10 in the sealing device. The gasket body 11 of the spiral wound gasket 10 is formed by alternately winding a metal thin strip (hoop) 11a such as aluminum and a cushioning material (filler) 11b made of non-metallic material such as graphite or glass seal in a spiral shape. The winding end is fixed by welding or the like. An inner ring 12 is attached to the inside of the gasket body 11 to suppress deformation of the gasket body 11 inward in the radial direction due to a tightening force. Similarly, an outer ring 13 is attached to the outside of the gasket main body 11 and serves to suppress deformation of the gasket main body 11 in the radial direction due to the tightening force. The inner ring 12 and the outer ring 13 are usually made of stainless steel (SUS).

A sacrificial electrode 7 is disposed on the outer peripheral side of the outer ring 13 by galvanization. The sacrificial electrode 7 is made of a metal having a higher potential sequence in seawater than the flange portion (stainless steel or aluminum alloy), preferably cadmium, aluminum, zinc, magnesium alloy, or magnesium, and more preferably zinc. .
The sacrificial electrode 7 in the present embodiment is formed by galvanizing the surface of the outer ring 13. However, in addition to plating, the sacrificial electrode 7 may be fixed in the vicinity of the gap 9 with an adhesive. The arrangement of the sacrificial electrode 7 is appropriately selected depending on the use conditions such as the material of the flange portion, the temperature, and the application location.

FIG. 2 is a longitudinal sectional view of a sealing device in which the spiral wound gasket 10 according to the present embodiment is applied to the flange portions 5 and 6.
In the figure, the right side is a pipe 3 on the LNG ship side and has a flange portion 5. This pipe 3 is formed of the same aluminum alloy as the spherical tank of the LNG ship. Further, in the drawing, the left side is a pipe 4 of a fuel facility or the like and has a flange portion 6. The pipe 4 is generally formed of stainless steel for fire resistance. The two pipes 3 and 4 are connected by a plurality of bolts 14 and nuts 15 on the circumferences of the flange portions 5 and 6, respectively. The above-described spiral wound gasket 10 is inserted between the flange portions 5 and 6, and the surface of the outer ring 13 of the spiral wound gasket 10 is galvanized as a sacrificial electrode. A gap 9 is formed between the outer peripheral side of the spiral wound gasket 10 and the flange portion 5 or 6.

  LNG circulates through the pipe line 16 in the pipes 3 and 4 connected by the flange parts 5 and 6. Note that the fluid flowing through the pipe line 16 is not limited to LNG, and may be a cryogenic fluid such as LPG, DME, liquid ammonia, liquid hydrogen, liquid nitrogen, liquid oxygen, or the like.

Next, corrosion prevention of the flange portions 5 and 6 by the sacrificial electrode will be described with reference to FIG.
In FIG. 2, when the pipe 3 and the pipe 4 are formed of dissimilar metals of aluminum alloy and stainless steel, and the galvanized sacrificial electrode 7 is formed on the surface of the outer ring 13, the outer ring 13 and each flange of the gasket 10 are formed. When rainwater or seawater enters or stays in the gap 9 between the parts 5 and 6, a circuit is formed in which current flows between the three types of metals. At this time, among the three kinds of metals, the electric corrosion proceeds by concentrating on zinc having the highest potential sequence in the seawater, and the corrosion of the flange portions 5 and 6 can be prevented.
The sacrificial electrode 7 may be separately provided in the vicinity of the outer ring 13, and may be provided in the vicinity of the spiral wound gasket 10 in which electric corrosion occurs, or provided integrally with the spiral wound gasket 10.

As described above, in the gasket and the pipe using the gasket according to the present embodiment, among the pipes connected to the spherical tank of the LNG ship, the pipes 3a, 3b, 3c and 3d (in which pipes are formed in the horizontal direction) This is effective for the flange portions 5 and 6 of FIG. In the flange portions 5 and 6 in the horizontal direction, rainwater, seawater, and the like are likely to enter and stay in the gap 9 between the outer ring 13 and the flange portions 5 and 6. By disposing the electrode 7, corrosion of the flange portions 5, 6 or the spiral wound gasket 10 due to electric corrosion is prevented.

  Since the gap 9 is not filled with a soft member, it is possible to reliably inspect the gas leakage or the like during the gas leakage inspection of the flange portion, and to improve the reliability of the sealing device.

It is the one side longitudinal cross-sectional view of the spiral wound gasket concerning embodiment of this invention. It is a longitudinal cross-sectional view of the sealing device which applied the spiral wound gasket concerning embodiment of this invention to the flange part. It is a perspective view which shows the structure of a common moss type LNG ship. It is a top view of the spherical tank of a moss type LNG ship. It is a longitudinal cross-sectional view at the time of applying the conventional spiral wound gasket to a flange part.

Explanation of symbols

3, 4 Piping 5, 6 Flange 7 Sacrificial electrode 10 Spiral wound gasket (seal material)
11 Gasket body 12 Inner ring 13 Outer ring

Claims (7)

In a sealing device including a sealing member that seals between sealed members,
A sealing device, wherein a member having a higher potential row than the member to be sealed is disposed in the vicinity of the sealing member or the sealing member. The sealing device according to claim 1, wherein the member having a high potential row is a metal having a higher potential row in seawater than an aluminum alloy. 3. The sealing device according to claim 2, wherein the metal having a higher potential series in seawater than the aluminum alloy is cadmium, aluminum, zinc, a magnesium alloy, or magnesium. The sealing device according to claim 1, wherein the member having a high potential row is disposed on an outer peripheral side of the sealing member. 5. The sealing device according to claim 1, wherein the member having a high potential row is disposed by plating on an outer peripheral side of the seal member. The seal member seals between the members to be sealed, and a gasket body formed by alternately winding a metal hoop and a non-metallic material filler in a spiral shape;
An inner ring provided inside the gasket body;
In the spiral wound gasket constituted by the outer ring provided on the outside of the gasket body,
The sealing device according to any one of claims 1 to 5, wherein the outer ring is provided with a metal having a high potential series. In piping which has a piping joint which connects between members to be sealed through a sealing device, the sealing device is the sealing device according to any one of claims 1 to 6. Piping.

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