JP2007078003A - Gland packing and sealing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gland packing having small sliding resistance at a gland portion and high opening/closing durability and being applicable to a wide temperature range from a low temperature to a high temperature even when fluid to be handled has high pressure. <P>SOLUTION: The gland packing comprises an annular packing ring 1a formed of graphite containing PTFE, and an annular hard packing rings 1b arranged on both end faces of the packing ring 1a and each formed of a plastic material having higher hardness than the material for the packing ring 1a. The packing ring 1a is held between the hard packing rings 1b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention seals shaft parts such as a shaft that moves helically like a stem of a valve, a shaft that rotates like a rotary pump or a stirrer, and a shaft that reciprocates like a reciprocating pump or cylinder device. A gland packing that can cope with a wide range of temperature changes from low to high temperature, and that can improve durability and sealability with low sliding torque even at high pressures, and uses this gland packing. The present invention relates to a sealing device.

  Generally, seals for shaft parts such as valve stems, rotary pump rotary shafts, agitator rotary shafts, blower rotary shafts, mixer rotary shafts, reciprocating pump reciprocating operation shafts, reciprocating operation shafts of cylinder devices, etc. Conventionally, a gland packing and a sealing device using a gland packing have been widely used.

  As the gland packing, a braided packing obtained by braiding yarns made of fiber materials such as carbon fibers and aramid fibers into a desired shape by knitting one or a plurality of yarns, punching a sheet-like material, and processing it into a desired shape, A laminate packing obtained by press molding this with a mold or the like, a graphite packing using expanded graphite as a main material, a resin packing using a fluorine-based resin as a main material, and the like are known.

  Further, as a sealing device, for example, the above-described gland packing is filled in a cylindrical seal space formed between a staffin box formed in a valve body and a stem penetrating the staffin box, and the outer periphery of the staffin box is The inner surface of the gland packing is moved to the outer surface of the stem by tightening the gland nut screwed to the surface and pressurizing the gland packing in the axial direction of the stem through a packing presser fitted to the inlet side of the seal space. In addition, there is known a valve sealing device in which the outer peripheral surface of the gland packing is in close contact with the inner peripheral surface of the staffin box for sealing.

  By the way, in recent gland packing and sealing devices, a gland packing having a structure in which an annular packing ring formed of different materials is combined and a sealing device using the same are used in order to improve sealing performance and the like. (For example, refer to Patent Document 1, Patent Document 2, and Patent Document 3).

  For example, in a valve for controlling fluids such as boiler feed water and various gases, an annular packing made of polytetrafluoroethylene (PTFE) excellent in heat resistance, chemical resistance, self-lubricating property, etc., and polytetra A gland packing having a structure in which a ring packing formed of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) having characteristics comparable to that of fluoroethylene is combined, and a seal device using the same are used.

However, in the gland packing and the sealing device, when the pressure of the fluid exceeds 30 MPa, the gland packing is immediately worn with the opening / closing operation of the valve, the sealing function is lowered, and the fluid leaks from the gland portion. However, there is a problem that the opening / closing durability performance is extremely poor. For example, when the pressure of the fluid is 40 MPa, the gland packing is worn and leakage from the gland portion occurs only by opening and closing the valve about 50 times.
Therefore, in the gland packing and the sealing device, it has been difficult to realize durability that can withstand a high pressure of 30 MPa or more.
In addition, when the gland packing and the seal device are used in a manual type valve, when the fluid pressure becomes high, the sliding resistance of the gland increases, and the handle torque when the valve is opened and closed increases. There has been a problem that the opening / closing operation of the door becomes difficult.
Furthermore, the operating temperature range of the gland packing and the sealing device is relatively narrow, such as -20 ° C to 150 ° C, and it cannot be used in the temperature range of -50 ° C to 230 ° C, which is often required for manual valves. It was.
Japanese Patent No. 0329890 Japanese Patent No. 0324428 JP 07-217745 A

  The present invention has been made in view of such problems, and its purpose is to have a low sliding resistance at the ground portion and high switching durability even when the fluid to be handled is high pressure, and from low temperatures. An object of the present invention is to provide a gland packing capable of supporting a wide temperature range up to a high temperature and a sealing device using the same.

  The inventor of the present application forms dozens of types of gland packing by combining various ring packing rings made of various materials, and performs various tests on each gland packing by changing conditions such as fluid pressure and temperature. As a result of investigating sealing performance, durability, sliding resistance, etc., it was found that a packing ring made of graphite containing polytetrafluoroethylene (hereinafter referred to as PTFE containing graphite) and a plastic material having a hardness higher than that of the packing ring. It was found that the gland packing combined with the hard packing ring formed by the above method has the most excellent durability, sealing performance, sliding resistance and the like.

  The invention of claim 1 of the present invention was created through the above-described process, and is arranged on the annular packing ring formed of graphite-containing PTFE, and on both end faces of the packing ring, and is made from the material of the packing ring. It is composed of an annular hard packing ring formed of a plastic material having a high hardness, and is characterized in that the packing ring is held by the hard packing ring.

  The invention of claim 2 of the present invention is characterized in that, in the invention of claim 1, the annular hard packing ring is formed of polyetheretherketone.

  According to a third aspect of the present invention, a gland packing is filled in a cylindrical seal space formed between a staffin box and a shaft passing through the staffin box, and the gland packing is pressed in the axial direction of the shaft by a packing presser. 4. A sealing device in which a gap between the inner peripheral surface of the stuffing box and the outer peripheral surface of the shaft is sealed with a gland packing, and the gland packing is defined in claim 1, 2, or 3. It is characterized by a gland packing.

The gland packing and sealing device of the present invention is a PTFE annular packing ring made of graphite, which has excellent heat resistance, wear resistance, chemical resistance, etc., and is excellent in heat resistance, wear resistance, chemical resistance, etc.・ Since it is held by a rigid packing ring made of polyetheretherketone that exhibits excellent characteristics even under high pressure, it can fully handle a wide range of temperature ranges and high pressure conditions, and has high sealing performance And high opening and closing durability can be secured.
The gland packing and sealing device of the present invention uses a PTFE packing ring made of graphite excellent in wear resistance and the like, and a hard packing ring made of polyether ether ketone which is also excellent in wear resistance and the like. Therefore, when used for a valve, the sliding resistance of the ground portion is reduced, the increase in the handle torque of the valve can be suppressed, and the rotation of the handle of the valve can be easily performed.
Furthermore, since the gland packing and the sealing device of the present invention hold one packing ring with two hard packing rings, the gland packing itself becomes compact, and various devices such as valves can be made compact.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a gland packing 1 and a sealing device according to an embodiment of the present invention applied to a gland portion of a manual valve. The gland packing 1 and the sealing device seal a stem 3 portion of the valve. In addition to being able to handle a wide range of temperature ranges and high pressures, it has low sliding resistance and excellent durability, but it is also possible to achieve a compact valve. .

  The gland packing 1 includes an annular packing ring 1a formed of graphite-filled PTFE, and an annular hard packing formed of a plastic material having a hardness higher than that of the packing ring 1a. The ring 1b is configured such that one packing ring 1a is held between two hard packing rings 1b.

  That is, the packing ring 1a is made of graphite-containing PTFE (graphite powder is dispersed in PTFE, and the properties of PTFE lacking in properties such as compression creep resistance and wear resistance are strengthened) into an annular shape with a rectangular cross section. It is formed and has excellent characteristics such as heat resistance, wear resistance, chemical resistance, non-viscosity, self-lubrication characteristics, electrical characteristics, and the like. In this example, the packing ring 1 is formed of a material obtained by blending PTFE (polytetrafluoroethylene) with graphite powder (graphite powder).

  On the other hand, the hard packing ring 1b is formed in an annular shape having a rectangular cross section with a plastic material having a hardness higher than that of the packing ring 1a. In this example, polyether ether ketone, which is one of engineering plastics, is used. (PEEK: registered trademark). This polyetheretherketone has heat resistance (UL value 260 ° C), abrasion resistance (exhibits excellent slidability even under high temperature and high load), chemical resistance (a wide range of inorganic and organic solvents other than concentrated sulfuric acid) Excellent flame resistance), flame retardancy (V-0 flame retardance achieved with 1.5mm thick sample), hydrolysis resistance (steam above 250 ° C, thousands in high pressure water) Withstands the use of time, etc.).

As shown in FIG. 1, the sealing device using the gland packing 1 described above is inserted into the tubular staffin box 2a formed in the valve body 2 and the staffin box 2a so that the body 2 can rotate and move up and down. A cylindrical seal space formed between the stem 3 and the stem 3 that is screwed to the metal is sequentially filled with a metal saddle ring 4, a hard packing ring 1b, a packing ring 1a, and a hard packing ring 1b, and the seal space A metal cylindrical packing retainer 5 is fitted on the inlet side, and a gland nut 6 screwed to the outer peripheral surface of the staffin box 2a is tightened to form a packing ring 1a that constitutes the gland packing 1 with the packing retainer 5 and the saddle wheel. The gland portion of the valve is sealed by pressurizing the hard packing ring 1b in the axial direction of the stem 3. It is.
In FIG. 1, reference numeral 7 denotes a panel nut screwed to the outer peripheral surface of the staffin box 2a.

In this sealing device, the PTFE packing ring 1a made of graphite having excellent heat resistance and wear resistance is excellent in heat resistance and wear resistance, and exhibits excellent slidability even under high temperature and high pressure. Since the gland packing 1 is held by a rigid packing ring 1b made of polyetheretherketone, it can sufficiently handle a wide range of temperature ranges and high pressure conditions, and has high sealing performance and high opening and closing. Durability can be ensured.
In addition, in this sealing device, since the gland packing 1 comprising the PTFE packing ring 1a made of graphite and the hard packing ring 1b made of polyetheretherketone is used, the pressure of the fluid to be handled becomes high. However, the sliding resistance of the ground portion is small, an increase in the valve handle torque can be suppressed, and the valve handle can be easily rotated.
Further, in this sealing device, since the gland packing 1 in which one packing ring 1a is held by two hard packing rings 1b is used, the gland packing 1 itself becomes compact, and as a result, the valve Can be made compact.

In order to confirm the durability and sliding torque of the sealing device using the gland packing 1 of the present invention, the sealing device using the gland packing 1 of the present invention and the conventional gland packing (combination of PTFE and PFA) Durability and other tests were conducted using a seal device using a stencil as a manual valve. As a result, the results shown in Table 1 below were obtained.
The gland packing 1 of the present invention and the conventional gland packing were formed in the same shape and tested.

  As is clear from Table 1, the sealing device using the gland packing 1 of the present invention is superior in durability to the sealing device using the conventional gland packing and has a small sliding resistance. It was found that the temperature range was also wide.

  In the above embodiment, the gland packing 1 and the sealing device are used for a manual valve. However, in other embodiments, the gland packing 1 and the sealing device are automatically operated. It may be used for a valve.

  In the above-described embodiment, the gland packing 1 and the sealing device are used for the valve in which the stem 3 moves helically. However, in the other embodiments, the stem 3 rotates or reciprocates. You may make it use the gland packing 1 and a sealing device for a valve | bulb.

  In the above embodiment, the packing presser 5 for holding the gland packing 1 is fastened by the gland nut 6 screwed to the outer peripheral surface of the staffin box 2a. However, in other embodiments, the packing presser 5 is tightened. The presser 5 may be tightened with a flange or an internal screw type member.

  In the above embodiment, the hard packing ring 1b is formed in a ring shape by polyether ether ketone, but in other embodiments, the hard packing ring 1b is harder than the packing ring 1a. You may make it form with another resin material. For example, the hard packing ring 1b may be formed of polyvinylidene fluoride / (PVDF).

  In the above embodiment, the cross-sectional shapes of the packing ring 1a and the hard packing ring 1b are formed in a rectangular shape, but in other embodiments, the packing ring 1a and the hard packing ring 1b The cross-sectional shape may be formed in a thin plate shape or a V-shape, or may be formed in other shapes.

  The present invention is used for sealing a shaft portion of a valve. A shaft portion such as a rotating shaft such as a rotary pump or a stirrer or a shaft such as a reciprocating shaft such as a reciprocating pump or cylinder device is used. It can also be applied to seal.

It is an expanded longitudinal cross-sectional view of the gland | grand | ground part of the manual type valve | bulb using the gland packing and seal device which concern on embodiment of this invention.

Explanation of symbols

  1 is a gland packing, 1a is a packing ring, 1b is a hard packing ring, 2a is a staffin box, 3 is a shaft, and 5 is a packing presser.

Claims (3)

  An annular packing ring (1a) formed of graphite-filled PTFE, and an annular hard packing formed of a plastic material that is disposed on both end faces of the packing ring (1a) and has a hardness higher than that of the packing ring (1a). A gland packing comprising a ring (1b), wherein the packing ring (1a) is held by a hard packing ring (1b).   The gland packing according to claim 1, wherein the ring-shaped hard packing ring (1b) is formed of polyether ether ketone.   The cylindrical seal space formed between the staffin box (2a) and the shaft (3) passing therethrough is filled with the gland packing (1), and the gland packing (1) is held by the packing presser (5). In the sealing device, the gap between the inner peripheral surface of the stuffing box (2a) and the outer peripheral surface of the shaft (3) is sealed by the gland packing (1) by tightening in the axial direction of the shaft (3). 4. The sealing device according to claim 1, wherein the gland packing (1) is the gland packing (1) according to claim 1, 2 or 3.

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