JPH08166063A - Packing assembly body - Google Patents

Abstract

PURPOSE: To provide a packing assembly body where the shaft torque is kept small, and the sealabffity is excellent in a case where the expanded graphite ring packing is used for the packing. CONSTITUTION: A packing assembly body to be mounted on a stuffing box comprises a plurality of expanded graphite ring packings A and at least two auxiliary ring packings B which are larger in inner diameter and larger in outer diameter than those of the ring packings, and formed of the material of large compression strength. The number of the expanded graphite ring packings is reduced by this combination, and the shaft torque can be reduced tough the sealability is slightly deteriorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a ring-shaped packing assembly which is mounted in a stuffing box at a portion where a shaft such as a valve or a pump penetrates to prevent fluid from leaking from the shaft.

[0002]

2. Description of the Related Art Conventionally, as a gland packing used to prevent fluid from leaking from a valve stem or a rotary shaft (hereinafter referred to as a shaft), heat-resistant fibers such as asbestos fiber and carbon fiber are woven eight times. The so-called braided packing, which is braided into bag knitting or lattice knitting, impregnated with a lubricant, or surface-treated, is often used.
Since such packing is excellent in heat resistance, chemical resistance, wear resistance and the like, it is still widely used at present, but since it tends to cause stress relaxation to some extent, in order to maintain the sealing property, Often requires a fairly large number of rings.

FIG. 10 shows a typical structure example in which a gland packing is loaded into a stuffing box to form a shaft sealing portion. In the figure, 1 is a shaft, 2 is a stuffing box, 3 is a gland packing, 4 is a packing retainer, 5 is a tightening bolt, and 6 is a nut. The loaded gland packing 3 is tightened with a bolt to obtain a required surface pressure. Then, the inner peripheral surface of the gland packing is pressed against the peripheral surface of the shaft to seal the shaft.

However, recently, due to an increase in awareness of environmental problems, minute leaks have become a problem, and expanded graphite sheets having less stress relaxation and high sealing property are laminated or spirally wound. Post ring molded expanded graphite ring packing has come into use. Such expanded graphite ring packing has excellent sealing properties, but on the other hand, scale-like expanded graphite particles are very likely to stick to sliding surfaces such as stems, causing sticking phenomenon and loading many in the stuffing box. Then, the shaft torque increases, and in some cases, a problem such as the shaft not rotating can occur.

Therefore, in using the expanded graphite ring packing, there is a tendency to reduce the number to be loaded as compared with the conventional braided packing such as asbestos fiber, and it is a problem when redesigning equipment such as valves. However, there was a problem when changing the ring packing used for valves used in plants etc. from the braided packing to the expanded graphite ring packing.

[0006]

As described above, when it is desired to reduce the number of packings to be loaded, one metal sleeve is loaded in the empty space of the stuffing box instead, and the packing is placed on top of it. Means for loading expanded graphite ring packing are commonly used. However, when loading such a sleeve, the depth inside the stuffing box should be measured in advance, and the individual stuffing box should be calibrated beforehand in consideration of the number (or total height) of expanded graphite ring packings to be loaded. Since it is necessary to individually manufacture a sleeve having a height suitable for the above, it is difficult to replace many packings in a short period of time such as periodical repair of the plant.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and when an expanded graphite ring packing is used, the packing torque of the shaft assembly is kept small and the sealing property is good. The main purpose is to provide.

[0008]

SUMMARY OF THE INVENTION The present invention is a packing assembly for loading a stuffing box in a shaft penetrating portion to prevent fluid leakage from the shaft, wherein the packing assembly is a plurality of expanded graphite ring packings. And the inner diameter is larger and the outer diameter is smaller than this expanded graphite ring packing,
The gist is that it is configured by a combination with at least two auxiliary ring packings made of a material having high compressive strength.

The number of expanded graphite ring packings to be loaded into the stuffing box is determined by the usage conditions (mainly fluid pressure) of the valve to be loaded, and the auxiliary ring packing is increased or decreased depending on the depth of the stuffing box. The depth of the stuffing box to be loaded varies depending on the individual valve, etc., and the expanded graphite ring packing and spacer packing (braided packing used to prevent deformation of the expanded graphite ring packing) as necessary. The packing assembly is constructed by loading the required number of the auxiliary ring packings in the remaining space in which the packings have been loaded.

As the expanded graphite ring packing, a braided packing (generally called a spacer packing) in which metal wires or the like are braided may be combined in order to prevent the packing from being deformed. Further, it may be impregnated to reduce the axial torque of the expanded graphite ring packing.

Examples of the auxiliary ring packing include the following. Metal: Stainless steel, steel, aluminum, etc. Carbon sintered body: Ceramic sintered body: Silicon carbide, silicon nitride, carbon nitride, etc. Resin molded body: engineering plastics such as epoxy resin and Senyi reinforced resin, auxiliary ring packing is above It may be formed of a material other than the above, and may be used alone or in combination depending on use conditions (compressive strength, heat resistance, etc.). In the case of the auxiliary ring packing, since the expanded graphite ring packing is used after being tightened to a surface pressure of about 5 kgf / mm ² , it has a compressive strength of 10 kgf / mm ² or more (preferably 20 kgf / mm ² ). Is used.

The auxiliary ring packing is larger than the inner diameter of the expanded graphite ring packing by 0.1 to 3.0 mm (preferably 0.1 to 1.0 mm) and is larger than the outer diameter by 0.1 to 2.0 mm.
mm (preferably 0.1-1.0 mm), height is 1 /
The range of 2 to 3/2 times (preferably 1/2 to 1 times) is suitable, and it is easy to insert into the stuffing box considering the coefficient of thermal expansion, stress deformation, etc. for each material, and Determine dimensions so that you do not bite.

[0013]

According to the above construction, when bolts are tightened to the packing assembly after loading, the expanded graphite ring packing is compressed and its inner peripheral surface is pressed against the shaft surface, but the auxiliary ring packing is expanded graphite. Since it is made of a material having an inner diameter larger than the ring packing, an outer diameter smaller than that of the ring packing, and a large compressive strength, it is not pressed against the shaft surface.
Therefore, as compared with the case where only the expanded graphite ring packing is used, the axial torque is kept small and a good sealing property is obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the packing assembly according to the present invention will be specifically described with reference to the drawings together with comparative examples. 1 to 3 each show a schematic structure of a gland packing assembly according to the present invention, and FIGS. 4 to 6 respectively show a gland packing assembly according to a comparative example. In the drawing, A is an expanded graphite ring packing, B is an auxiliary ring packing, C is a spacer packing, and D is an asbestos braided packing.

Example 1 (FIG. 1): SUS30 under six T / # 2200 glass seal packings (inner diameter 26 mm, outer diameter 42 mm, height 8 mm) as expanded graphite ring packing.
4 auxiliary ring packing (inner diameter 26.2 mm, outer diameter 41.
5mm, height 8mm) 4 pieces combined.

Example 2 (FIG. 2): T / # 2200 Graseal packing (inner diameter 26 mm, outer diameter 42 mm, height 8 mm) as expanded graphite ring packing, T / # 2930 as spacer packing above and below four pieces One high guard packing (inner diameter 26 mm, outer diameter 42 mm, height 8 mm) was combined one by one, and four SUS304 auxiliary ring packings (inner diameter 26.2 mm, outer diameter 41.5 mm, height 8 mm) were combined under them. .

Example 3 (FIG. 3): T / # 2200 glass seal packing (inner diameter 26 mm, outer diameter 42 mm, height 8 mm) as expander graphite ring packing, T / # 2930 as spacer packing above and below High guard packing (inner diameter 26 mm, outer diameter 42 mm, height 8 mm) was combined one by one, and 6 SUS304 auxiliary ring packings (inner diameter 26.2 mm, outer diameter 41.5 mm, height 8 mm) were combined under them. .

Comparative Example 1 (FIG. 4): T / # 2920 high temperature valve packing (inner diameter 26
mm, outer diameter 42 mm, height 8 mm).

Comparative Example 2 (FIG. 5): Ten T / # 2200 glass seal packings (inner diameter 26 mm, outer diameter 42 mm, height 8 mm) were combined as expanded graphite ring packing.

Comparative Example 3 (FIG. 6): T / # 2200 Graseal packing (26 mm inner diameter, 42 mm outer diameter, 8 mm height) as ring packing made of expanded graphite, T / # 2930 as spacer packing above and below Combined one high guard packing (inside diameter 26 mm, outside diameter 42 mm, height 8 mm).

The auxiliary ring packing B is shown in FIG.
It is based on the perfect ring type shown in (a), but
As shown in (b) to (h), a split ring may be used. Further, in order to facilitate insertion into the stuffing box, as shown in FIGS. 8 (a) to 8 (e), some or all of the four corners of the upper and lower surfaces of the packing inner and outer diameters may be chamfered.

The gland packing assembly shown in the above-mentioned examples and comparative examples was mounted on a tester as shown in FIG. 9, and the packing was tightened at a surface pressure of 500 kgf / cm ² , and the axial torque and N ₂ gas sealability were improved. The measured results are shown in Table 1.
In FIG. 9, 7 is a tester main body, 8 is a shaft, 9 is a packing retainer, 10 is a tightening bolt, 11 is a lantern ring, P is a test gland packing assembly, 12 is a ball bearing, and 13 is gas pressurization. Mouth, 14 is a gas outlet.

[0023]

[Table 1]

As shown in Table 1, all of Examples 1 to 3 using the gland packing assembly according to the present invention have a good sealing property, and the sealing property is somewhat improved by reducing the number of expanded graphite ring-shaped packings. Although it decreases, it is possible to reduce the shaft torque. On the other hand, as shown in Comparative Example 1, it was recognized that the asbestos braided packing was inferior in sealing property to the expanded graphite ring-shaped packing. Further, it was confirmed that the ones having a large number of expanded graphite ring-shaped packings as shown in Comparative Examples 2 and 3 have no problem in the sealing property, but the shaft torque is large, so that the shaft becomes hard to rotate.

[0025]

As described above, according to the present invention,
When loading expanded graphite ring packing into a stuffing box designed for braided packing such as asbestos with a large number of packings to be loaded, the inner diameter is larger, the outer diameter is smaller than the expanded graphite ring packing, and the packing is compressed. Since the auxiliary ring packing made of a material having high strength is combined, a packing assembly having a small axial torque and a good sealing property can be obtained.

In addition, when an expanded graphite ring-shaped packing or spacer ring is used, the remaining space of the stuffing box is conventionally filled with a metal sleeve, which is an integrally molded product. It was indispensable to measure the depth, but with the valves existing in the actual plant, it may not be possible to measure the depth depending on the surrounding conditions, and it is difficult to design the height of the metal sleeve. Although accompanied, by using the auxiliary ring-shaped packing, the work of depth measurement performed in advance becomes unnecessary, and the same number of auxiliary ring-shaped packings as the conventional one can be inserted by inserting the necessary number of auxiliary ring-shaped packings in the packing loading process. There is an advantage that an effect can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a gland packing assembly showing a first embodiment according to the present invention.

FIG. 2 is a configuration diagram of a gland packing assembly showing a second embodiment according to the present invention.

FIG. 3 is a configuration diagram of a gland packing assembly showing a third embodiment according to the present invention.

FIG. 4 is a configuration diagram of a gland packing assembly showing a first comparative example.

FIG. 5 is a configuration diagram of a gland packing assembly showing a second comparative example.

FIG. 6 is a configuration diagram of a gland packing assembly showing a third comparative example.

FIG. 7 is a perspective view showing various shapes of an auxiliary ring packing.

FIG. 8 is a cross-sectional view showing various chamfered shapes of the auxiliary ring packing.

FIG. 9 is a cross-sectional view of a gland packing tester.

FIG. 10 is a sectional view of a shaft sealing portion in which a conventional gland packing is loaded in a stuffing box.

[Explanation of symbols]

 1 Shaft (or stem) 2 Stuffing box 3 Gland packing 4 Packing retainer 5 Tightening bolts 6 Nuts A Expanded graphite ring packing B Auxiliary ring packing C Spacer packing D Asbestos braided packing 7 Testing machine body 8 Shaft (or stem) 9 Packing retainer 10 Tightening bolt 11 Lantern ring P Gland packing assembly for test 12 Ball bearing 13 Gas pressurizing port 14 Gas outlet

Claims (2)

[Claims] 1. A packing assembly that is loaded in a stuffing box of a shaft penetrating portion to prevent fluid leakage from a shaft, wherein the packing assembly includes a plurality of expanded graphite ring packings and the expanded graphite ring packings. A packing assembly characterized by being configured in combination with at least two auxiliary ring packings made of a material having a larger inner diameter, a smaller outer diameter, and a high compressive strength. 2. The compressive strength 1 is applied to the auxiliary ring packing.
The packing assembly according to claim 1, wherein any one of 0 kgf / mm ² or more of metal, carbon sintered body, ceramic sintered body, and molded body of synthetic resin is used alone or in combination.