JP2002340187A - Seal structure of pipe joint for high temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal structure of a pipe joint for a high temperature suitably usable even in a high temperature environment such as a flame propagating pipe part used for a gas turbine combustor of a power plant, and superior in follow-up performance to a shaft directional inclination of a pipe by the thermal expansion. SOLUTION: Main seal packing 4 molded in a ring shape by pressurization by winding a mica sheet in layers is loaded in a packing chamber 3 formed in an outer peripheral part of the pipe 1. A mesh spring 5 molded in a ring shape after knitting or weaving a metallic fine line is loaded on both ends of this main seal packing 4, and is pressurized by a packing presser member 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing structure for a high temperature pipe joint, and more particularly to a boiler, a turbine,
The present invention relates to a high-temperature pipe joint seal structure that can be suitably used for sealing pipe joints under high-temperature environmental conditions such as an incinerator.

[0002]

2. Description of the Related Art Conventionally, as a sealing structure of a pipe joint, for example, there is a structure using a gland packing made of an expanded graphite-based sealing material having excellent self-lubricating properties, thermal conductivity, chemical resistance and the like.

[0003]

However, in the above-described pipe joint sealing structure using a gland packing made of an expanded graphite sealing material, if the pipe is inclined under a high temperature environment when the pipe is inclined due to thermal influence, the expanded graphite system is not used. Since the sealing material has poor followability with respect to the inclination of the pipe and has a large stress relaxation, the sealing property is reduced in a short period of time, causing gas leakage.
In addition, the expanded graphite-based sealing material is severely deteriorated by oxidative consumption under a high temperature condition exceeding about 600 ° C., so that the sealing characteristics cannot be maintained. Therefore, for example, it cannot be used in a high temperature environment exceeding about 450 to 600 ° C., such as a flame transmission pipe used in a gas turbine combustor of a power plant. There is a demand for a seal structure for a high-temperature pipe joint that can be used in the above.

SUMMARY OF THE INVENTION An object of the present invention is to meet the above-mentioned demands, and is excellent in oxidation resistance and elasticity at high temperatures, and is used in a high-temperature environment such as a flame propagation tube used in a gas turbine combustor of a power plant. An object of the present invention is to provide a seal structure for a high-temperature pipe joint that can be suitably used even under the pipe and has excellent followability with respect to the axial inclination of the pipe due to thermal expansion.

[0005]

According to the present invention, a cylindrical packing chamber is formed on the outer periphery of a pipe having a pipe penetration having an inner diameter larger than the outer diameter of the pipe to be connected. A high-pressure pipe joint having a gasket holding member on at least one side in the axial direction of the main seal packing, wherein a mica sheet is wound around the packing chamber and formed into a ring-shaped pressure; And a mesh spring formed by knitting or weaving a metal thin wire and then forming a ring shape. In this case, it is preferable to use a mica sheet containing 80% or more of gold mica in order to enhance heat resistance.

[0006]

[Function] A ring molded product of a main seal packing formed by winding a mica sheet into a ring and press-molding it in a ring shape has excellent oxidation resistance at high temperatures, and in order to ensure elasticity at high temperatures, under high temperature conditions. Also, the sealing characteristics can be secured over a long use period. The mesh spring, which is arranged on both ends in the axial direction of the main seal packing and formed by weaving and weaving a thin metal wire, has heat resistance and is highly resilient. Thus, the decrease in the tightening pressure applied can be compensated. Further, since both the main seal packing and the mesh spring can ensure elasticity at a high temperature, the main seal packing and the mesh spring can follow the inclination of the pipe caused by the thermal influence.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a seal structure for a high temperature pipe joint according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view of a sealing structure of a high-temperature pipe joint. The high-temperature pipe joint is connected to a wall member W for partitioning a high-temperature fluid side A and an atmosphere side B in a pressure vessel, equipment, or the like. Forming a pipe penetration portion 2 having an inner diameter larger than the outer diameter,
A cylindrical space around the outer periphery of the pipe 1 in the pipe penetration 2;
That is, the packing chamber 3 is formed. One or two or more (two in the illustrated example) main seal packings 4 are loaded into the packing chamber 3, and mesh springs 5, 5 are provided and loaded at both axial ends of the main seal packing 4. . A packing holding member 6 is provided on one axial side of the packing chamber 3, and the packing holding member 6 presses the mesh spring 5 and the main seal packing 4 toward the wall member W.

The main seal packing 4 is formed by winding a mica sheet, more preferably a mica sheet containing 80% or more of gold mica (phlogopite), and press-molding the wound body into a ring shape. Mesh spring 5 is SUS3
It is formed by shaping a thin metal wire knitted object obtained by knitting a thin metal wire such as 16 into a weft knitting or vertical knitting structure, or a thin metal wire woven body obtained by weaving a thin metal wire into a plain weaving texture.

According to the high-temperature pipe joint seal structure having the above-described structure, even if the pipe 1 is inclined due to the thermal effect under high-temperature environmental conditions, the ring-shaped main seal packing 4 made of mica sheet is used. , And a ring-shaped mesh spring 5 made of a knitted object or a woven body made of a thin metal wire can ensure elasticity at a high temperature, and can follow the inclination of the pipe 1.
It is possible to secure gas-tight sealing without forming a gap between the inner peripheral surface of the pipe and the outer peripheral surface of the pipe 1, thereby preventing gas leakage.
In addition, the main seal packing 4 made of mica sheet has excellent oxidation resistance at high temperatures.
Even in a high temperature environment exceeding the vicinity, there is no oxidative consumption, and in this respect, the sealing characteristics can be secured for a long period of time. Further, the ring-shaped mesh spring 5 made of a knitted or woven metal thin wire has heat resistance,
Because of its high elasticity, it can be ensured even under high temperature conditions without reducing the tightening pressure of the main seal packing 4 by the packing holding member 6.

In the above embodiment, the case where the main seal packing 4 and the mesh spring 5 are pressed by the packing pressing member 6 from only one side has been described.
As shown in FIG. 2, the present invention can be similarly applied to a mode in which the main seal packing 4 and the mesh spring 5 are pressed from both sides by the packing pressing members 6, 6.

A compression restoring test was carried out in the following example using a combination of the main seal packing 4 made of a mica sheet and a mesh spring 5 made of a thin metal wire, and in the following comparative example using an expanded graphite packing.

(Embodiment) The main seal packing 4 is combined with a mesh spring 5 to form a main seal packing 4 with a mica sheet wound thereon and formed into a ring-shaped pressure (mica ring). Spring 5
Is formed by knitting or weaving a fine wire of SUS316 and then forming it into a ring. These two main seal packings 4 and 2
The inner diameter a of the ring in which the mesh springs 5 are combined is 110 mm, the outer diameter b is 124 mm, the axial length (height) H is 20 mm (the axial length of one main seal packing 4 is 7 mm, and the length of one mesh spring 5 in the axial direction is 3 mm).

(Comparative Example) The expanded graphite packing of the comparative example is formed by compression-molding expanded graphite into a ring shape. The inner diameter is 110 mm, the outer diameter is 124 mm, and the axial length (height) is 20 mm. Things.

As shown in the schematic sectional view of FIG. 3, an Amsler type compression / tensile testing machine is used for the apparatus used for the compression restoring test of the above-mentioned embodiment and comparative example, and a test jig (packing presser) 10 ( 110.5mm inside diameter, 123.5m outside diameter
m), load transducer (tightening pressure record) 11, displacement transducer (compression amount record) 12, dynamic strain gauge 13, and XY recorder 14
It consists of.

A compression restoration test was performed using the above-described apparatus in the following manner. The test method is as follows. At room temperature, a test jig 10 of the test apparatus shown in FIG. 3 is mounted on a test jig 10 (packing obtained by combining a main seal packing (mica ring) and a mesh spring) T or a comparative product (expanded graphite packing) P, each having a tightening pressure of 49.0 MPa (5
Up to about 9.8 MPa (10 Kgf / cm ² ).
Tighten 0Kgf / cm ²⁾ / min, to measure the amount of compression when the displacement transducer 12, of comparing relationships compression ratio with both the tightening pressure.

FIG. 4 shows the test results of the compressibility at each tightening pressure of the packing. From this result, for example, when the tightening pressure is 4
The compression ratio at 9.0 MPa is about 30% in the example, whereas it is about 20% in the comparative example. Therefore, the example has a lower fluid leakage than the comparative example. The occurrence was remarkably reduced, and it was confirmed that excellent sealing characteristics were secured.

Incidentally, the results of the heat loss test of the mica ring as the main seal packing and the expanded graphite packing are as shown in FIG. Regarding the test conditions, the test atmosphere is an exposure heating in an electric furnace, and the test time is 1 hour at each temperature.

As a result of the heat loss test shown in FIG. 5, when the expanded graphite packing exceeds 600 ° C., oxidative consumption is intense and the heat loss rate is remarkable, but in mica ring, weight loss other than the binder occurs even at around 600 ° C. It was found that the heat loss rate was extremely low, and the sealing property could be ensured even under a high temperature condition exceeding 450 to 600 °. Needless to say, the seal structure of the high temperature pipe joint of the present invention can be similarly applied to a shaft sealing portion of a rotating shaft or a reciprocating shaft.

[0020]

According to the seal structure for a high temperature pipe joint of the present invention, the main seal packing is made of a mica sheet having excellent oxidation resistance and elasticity at high temperatures, and a thin metal wire having excellent heat resistance and elasticity. Since it is loaded in the packing chamber in combination with the mesh spring, it can be used suitably even under high temperature environment conditions, and it has excellent followability to the inclination of the pipe due to thermal expansion, ensuring the sealing characteristics, and Advantageously, the structure is simple and can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a seal structure of a high-temperature pipe joint according to an embodiment.

FIG. 2 is a schematic sectional view of a seal structure of a high-temperature pipe joint according to another embodiment.

FIG. 3 is a schematic sectional view of a compression recovery test apparatus.

FIG. 4 is a table showing the results of a compression restoration test of an embodiment product and a comparative product.

FIG. 5 is a table showing the results of a heat loss test of mica ring and expanded graphite packing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piping 2 Piping penetration part 3 Packing room 4 Main seal packing 5 Mesh spring 6 Packing holding member

Claims (2)

[Claims] 1. A piping chamber having an inner diameter larger than an outer diameter of a pipe to be connected, a packing chamber formed in a cylindrical shape on an outer peripheral portion of the pipe in the pipe penetrating section, and an axial direction of the packing chamber. In the high temperature pipe joint having a packing holding member on at least one side, a main seal packing formed by winding a mica sheet into a ring shape and forming a ring shape in the packing chamber, and disposed at both axial ends of the main seal packing. And a mesh spring formed by knitting and weaving a thin metal wire and then forming a ring shape. 2. The sealing structure for a high temperature pipe joint according to claim 1, wherein said mica sheet contains 80% or more of gold mica.