WO2003027546A1

WO2003027546A1 - Gland packing and sealing apparatus comprising it

Info

Publication number: WO2003027546A1
Application number: PCT/JP2002/009787
Authority: WO
Inventors: Makoto Ishida
Original assignee: Nippon Valqua Industries, Ltd.
Priority date: 2001-09-26
Filing date: 2002-09-24
Publication date: 2003-04-03
Also published as: US20040251635A1; US7011312B2; DE60207595D1; JP2003097719A; DE60207595T2; EP1436534B1; EP1436534A1; JP4958350B2

Abstract

To provide a novel gland packing and a sealing apparatus comprising this, wherein the gland packing displays high and stable sealability for a stem and an inner wall surface of a stuffing box even for uses further requesting the movability (rotation and reciprocating movement), and further, gives excellent effects, such as decrease of moving resistance of a stem, shape stability, adaptability to a corroded and worn-out stem and stuffing box, function for receiving shafts, easiness of equipment, simplification of sealing structure, and compactness of a sealing apparatus. The gland packing, according to the present invention, is a ring packing of which the cross sectional shape is a quadrilateral, wherein both two edges at inner and outer diameter sides of the quadrilateral are parallel to a central axis of the gland packing, and wherein the other two edges have slopes of the same orientation as to an axis perpendicular to the central axis, with the gland packing being characterized in that an inner-diameter-side acute angle portion and an outer-diameter-side acute angle portion of the quadrilateral are made flat portions.

Description

DESCRIPTION

Gland Packing and Sealing Apparatus Comprising It

TECHNICAL FIELD

The present invention relates to a gland packing and a sealing apparatus

comprising this.

Particularly, the present, invention relates to a gland packing and a sealing

apparatus comprising this, wherein the gland packing is, for example, equipped in a

stuffing box and can effectively seal such as a stem in this stuffing box.

More particularly, the present invention relates to a gland packing and a sealing

apparatus comprising this, wherein the gland packing can seal moving portions of such as

rotary pumps, valves, stirrers, and reciprocating pumps, and is effective when it is utilized

in order to fit for various moving properties and all the sealing requisite properties of such

as a stem.

BACKGROUND ART

As to a gland packing which is equipped in a stuffing box and which seals such

as a stem in the stuffing box and inner wall surfaces of the stuffing box, hitherto, the cross

sectional shape thereof has in general been a rectangle (square or oblong), a parallelogram,

or a trapezoid having a right angle, and it has been generally known that at least any two of

the gland packings are mutually attached closely, piled, and then used. However, conventional gland packings have various problems. For example,

when at least two gland packings of which all the cross sectional shapes are rectangles

above are piled and equipped to a stem, there are problems such that: there is much scatter

of the extension and deformation of the gland packings in the vertical directions

(hereinafter, referred to as "in the directions of the inner and outer diameters") to the

tightening face pressure of the packing holder; and the exceedingly tightened portions and

the loosely tightened portions easily coexist. Therefore, the tightening face pressure of

the packing holder is inevitably increased exceedingly. Therewith, there is a demerit of

increasing the moving resistance and required torque of the stem, or there is a fault such

that: the gland packing materials are thrust into an opening at the stem side, and then

protruded; and therefore the lowering of the sealing performance (sealability) and the

leakage of enclosed materials are caused.

Accordingly, an attempt to facilitate the extension and deformation of the gland

packing and to lower the tightening face pressure of the packing holder is made by

comparatively lowering the density of the gland packing as used (namely, softening the

gland packing). However, because of the character such that the extension and

deformation amount in the directions of the inner and outer diameters of the

aforementioned low-density gland packing is smaller than the compression and

deformation amount in the direction of tightening the packing holder, it was necessary to

further increase the tightening face pressure of the packing holder finally so that the stem

would be sealed sufficiently. Furthermore, because the strain ratio (strain amount) of the

aforementioned low-density gland packing is large, the number of gland packings necessary for sealing the stem may exceed an acceptable limit in the stuffing box, and

besides there is a demerit of not achieving the function as a shaft receiver that prevents a

moving error or vibration of the stem due to its softness, and there is also a problem of the

permeation and leakage of the material itself because of the low density.

On the other hand, if the density is made high, the shape stability of the gland

packing is improved, and the gland packing can be made excellent in such as functions as

the shaft receiver. However, the extension and deformation amount in the directions of

the inner and outer diameters to the tightening face pressure of the packing holder is

fundamentally small. Therefore, it is necessary to further increase the tightening face

pressure of the packing holder so that the stem would be sealed sufficiently. Therewith,

caused are problems such that the sealing apparatus is enlarged and the handling

convenience is lost.

As to the sealing apparatus, in addition to those which have a structure in which

main packings of a kind are used in the above way, sealing apparatuses for such as stems in

which at least two kinds of gland packings comprised of different materials or having

different properties are mutually attached and equipped in a stuffing box have been well

known hitherto. However, the reason that such a structure is selected is that at least two

requisite or deficient performances (e.g. sealability, heat resistance, pressure resistance,

and frictional resistance) are satisfied at a stroke. This was impossible for conventional

gland packings of a kind alone. Therefore, in view of easiness and simplification of the

sealing apparatus, there are problems such that at least two kinds of gland packings

inevitably cannot help being equipped as the main packings. In addition, USP 4,328,974 discloses a sealing apparatus so as to have a stress

concentration in directions of the inner and outer diameters of a packing, in which a

low-density gland packing of which the cross sectional shape is a parallelogram is placed

between high-density gland packings of which the cross sectional shapes are trapezoids,

and the shapes of both are made not to be mutually attached, and besides they are piled and

equipped on a stem in a stuffing box, and thereafter the packings are mutually attached by

tightening a packing holder. However, in the sealing apparatus according to this prior

invention, there are various problems such that: 1) it is necessary to combine at least two

packings having different densities; 2) low-density packings having a large strain ratio

account for majority; 3) there is a stress concentration, but the number thereof is small; 4)

in other than the stress concentration, the tightening face pressure of the packing is not

transmitted more than that of a rectangular packing; and 5) the function of the low-density

packing portion as a shaft receiver is lowered.

DISCLOSURE OF THE INVENTION

OBJECT OF THE INVENTION

Accordingly, an object of the present invention is to provide a novel gland

packing and a sealing apparatus comprising this, wherein the gland packing displays high

and stable sealability for a stem and an inner wall surface of a stuffing box even for uses

further requesting the movability (rotation and reciprocating movement), and further, gives ■

excellent effects, such as decrease of moving resistance of a stem, shape stability,

adaptability to a corroded and worn-out stem and stuffing box, function for receiving shafts, easiness of equipment, simplification of sealing structure, and compactness of a sealing

apparatus.

SUMMARY OF THE INVENTION

The present inventor diligently studied to solve the above-mentioned problems,

and focused upon what improvement that has never been found should be carried out as to

the shape of the gland packing for the purpose of enabling it to display high sealability, and

then repeated various presumptions and experiments. The reason therefor is as follows.

In the past, as is mentioned above, there were examples in which the shapes were slightly

thought out. However, even in those cases, substantially expected are the effects as

obtained by focusing upon the combinations of materials or properties of gland packings

themselves, and as a result, by that alone, a definite effect can be obtained, whereas various

demerits are also caused. That is to say, he thought that the desirable effects of which the

improvement has hitherto been attempted by contriving the properties should be intended

to be given by carrying out a characteristic improvement mainly on the shape of the gland

packing.

Based on the above findings, he repeated trials and errors, and various studies.

As a result, he has completed the present invention by confirming that a novel gland

packing and a sealing apparatus comprising this can solve the above-mentioned problems

at a stroke; which gland packing is a so-called conical-plate-shaped gland packing, in

which the cross sectional shape of the ring portion of the ring packing is a quadrilateral,

and this quadrilateral consists of two inner-diameter-side and outer-diameter-side edges parallel to a central axis of the gland packing, and the other two edges facing each other

and having slopes of the same orientation as to an axis perpendicular to the central axis,

wherein portions corresponding to upper and lower ends in the direction of the central axis,

namely, an inner-diameter-side acute angle portion and an outer-diameter-side acute angle

portion of the gland packing, are made flat portions.

When a load is applied in the upward and downward directions of the central

axis, the gland packing, according to the present invention, is efficiently deformed in the

directions of the inner and outer diameters as if an umbrella were spread (so-called washer

deformation of conical plate diameter), so that a stress is caused. Therefore, for example,

when this gland packing is equipped to a stem in a stuffing box and then tightened, such as

greatly excellent sealability can be displayed even if the tightening load is either equal to

or less than the conventional tightening load. In addition, when the above equipment is

carried out, at least two gland packings are usually used similarly to the conventional

equipment. In addition to being characterized in that the gland packing according to the

present invention is conical-plate-shaped, as is mentioned above, the flat portions are

arranged at the upper and lower ends. Therefore, the gland packings can contact with

each other more certainly and stably than gland packings having no flat portions. The flat

portions contact with each other usually when the equipment is carried out in such a

manner that the slope orientation (shape) of one gland packing is opposite to that of its

neighboring gland packing in reference to the direction of the central axis. For example,

if this relation is repeated by at least two gland packings, then the equipment is carried out

in such a manner that the slopes are alternately oriented as a whole. As a result, as to the sealing apparatus in which the present invention gland packing is practically used, very

efficient and high sealability can be displayed multistagewise both to the inner and outer

diameter sides almost without depending upon the distance from the tightening portion,

because of the above certain and stable contact and of the so-called alternating equipment.

That is to say, a gland packing, according to the present invention, is a ring

packing of which the cross sectional shape is a quadrilateral, wherein both two edges at

inner and outer diameter sides of the quadrilateral are parallel to a central axis of the gland

packing, and wherein the other two edges have slopes of the same orientation as to an axis

perpendicular to the central axis,

with the gland packing being characterized in that an inner-diameter-side acute

angle portion and an outer-diameter-side acute angle portion of the quadrilateral are made

flat portions.

In addition, a sealing apparatus, according to the present invention, is equipped

with gland packings that are piled in a stuffing box, and seals the stuffing box,

with the sealing apparatus being characterized in that:

each of the gland packings is a gland packing in which flat portions are arranged

at an inner-diameter-side acute angle portion and an outer-diameter-side acute angle

portion of a ring packing of which the cross sectional shape is a quadrilateral including:

two edges at inner and outer diameter sides of the quadrilateral wherein the two edges are

parallel to a central axis of the gland packing; and the other two edges which have slopes

of the same orientation as to a vertical axis perpendicular to the central axis; and

at least one of the gland packings as equipped in the stuffing box is equipped therein in such a manner that the orientations of the slopes of the other two edges of the at

least one of the gland packings are different from those of the other gland packings.

BRIEF DESCRIPTION OF THE DRAWING

Fig. 1 (a) is a perspective view showing one working example of the present

invention gland packing. Fig. 1 (b) is a perspective view when the gland packing as

shown in Fig. 1 (a) is upside down. In addition, Fig. 1 (c) is a projective view in the

width direction of the gland packing as shown in Fig. 1 (a) or (b), and Fig. 1 (d) is a

projective view in the thickness direction of the gland packing as shown in Fig. 1 (a) or (b).

Both Figs. 2 (a) and (b) are partially cross sectional views showing one working

example of the present invention gland packing when the gland packing is cut by a plane

including a central axis 2a. Then, Fig. 2 (a) represents the case of α>β, and Fig. 2 (b)

represents the case of α<β.

Fig. 3 is a partially cross sectional view showing a gland packing as a referential

art when the gland packing is cut by a plane including a central axis 2a.

Both Figs. 4 (a) and (b) are partially end sectional views showing one working

including a central axis 2a. Then, Fig. 4 (a) represents the gland packing before

deformation, and Fig. 4 (b) represents the gland packing after deformation.

Fig.5 is a schematic cross sectional view showing one working example of a

sealing apparatus comprising the present invention gland packing. Fig. 5 (a) represents

the sealing apparatus before sealing (before a packing holder 8 is tightened), and Fig. 5 (b) represents the sealing apparatus after sealing (after a packing holder 8 is tightened).

Fig. 6 is a schematic cross sectional view showing one working example of a

sealing apparatus comprising the present invention gland packing. Fig. 6 (a) represents

the sealing apparatus before sealing (before a packing holder 8 is tightened), and Fig. 6 (b)

represents the sealing apparatus after sealing (after a packing holder 8 is tightened).

Fig.7 is a schematic cross sectional view showing one working example of a

sealing apparatus comprising the present invention gland packing and further being

equipped with an adaptor packing, and represents the sealing apparatus before sealing

(before a packing holder 8 is tightened).

Fig.8 is a schematic cross sectional view showing one working example of a

(before a packing holder 8 is tightened).

Fig.9 is a schematic cross sectional view showing one working example of a

sealing apparatus being equipped with a combination of the present invention gland

packing and a conventional-type gland packing, and represents the sealing apparatus before

sealing (before a packing holder 8 is tightened).

Fig.10 is a schematic cross sectional view showing one working example of a

sealing (before a packing holder 8 is tightened).

Fig.11 is a schematic cross sectional view showing one working example of a sealing apparatus being equipped with a combination of the present invention gland

sealing (before a packing holder 8 is tightened).

Fig.12 is a schematic cross sectional view showing one working example of a

equipped with an adaptor packing and a hard ring, and represents the sealing apparatus

before sealing (before a packing holder 8 is tightened).

Both Figs. 13 (a) and (b) are partially end sectional views showing one working

including a central axis 2a, wherein the structure of the present invention gland packing is

partially deformed.

Fig. 14 is a graph in which the X axis represents a "length distance" from the

pressurizing face of a packing holder, and in which the Y axis is an "inner-diameter-side

transmitted face pressure (MPa)" corresponding to this length distance.

Fig. 15 is a graph in which the X axis represents a "length distance" from the

pressurizing face of a packing holder, and in which the Y axis is an "outer-diameter-side

transmitted face pressure (MPa)" corresponding to this length distance.

Fig. 16 is a schematic cross sectional view showing one example of a sealing

apparatus for testing sealability of a gland packing (sealability-testing apparatus) as

mentioned in the Examples.

[Explanation of the Symbols]

1 Gland packing a Central axis

b Vertical axis to central axis

c Diametric axis

a Inner-diameter-side flat portion

b Inner-diameter-side obtuse angle portion

a Outer-diameter-side obtuse angle portion

b Outer-diameter-side flat portion

a' Inner-diameter-side acute angle portion

b' Outer-diameter-side acute angle portion

c Inner-diameter-side stress-concentrated point

c Outer-diameter-side stress-concentrated point

Stem

Stuffing box

Inner bottom portion of stuffing box

Packing holder

a Pressurizing face of packing holder

Tightening bolt

0 Adaptor packing

0a Gland packing of which the cross sectional shape is rectangular

0b Hard ring

1 O-ring

2 Tightening bolt 13 Pressurizing opening

14 Bearings

15 Stem (driving shaft)

16 Gas-enclosing portion

17 Thrust bearings

18 Portion equipped with torque wrench

DETAILED DESCRIPTION OF THE INVETION

Hereinafter, the details of the present invention gland packing and sealing

apparatus comprising this are specifically explained.

As is shown in Figs. 1 (a) and (b), the shape of the gland packing according to the

present invention (which may hereinafter be referred to as the present invention gland

packing) is a ring packing similarly to general gland packings.

The present invention gland packing is a gland packing in which portions

corresponding to the inner-diameter-side acute angle portion and the outer-diameter-side

acute angle portion of the gland packing of which the cross sectional shape of the ring

portion in the central axis direction (namely the cross sectional shape as cut by a plane

including the central axis) is a quadrilateral, namely, a portion corresponding to the upper

end and a portion corresponding to the lower end in view of a directional axis along the

central axis, are made flat portions.

Herein, the above quadrilateral is like the cross section of the gland packing as

shown in Fig. 3, and is a quadrilateral in which both an inner-diameter-side edge lc and an outer-diameter-side edge Id are parallel to a central axis 2a, and in which the other two

edges la and lb have slopes of the same orientation as to a vertical axis 2b perpendicular

to the aforementioned central axis 2a. As is shown in Fig. 3, the above slope means an

angle α or an angle β. The angle α is an angle between the vertical axis 2b and the edge

la, and the angle β is an angle between the vertical axis 2b and the edge lb. Furthermore,

the above slopes of the same orientation are defined as that the spreading of the above

angles are of the same orientation when the edge la and the edge lb cross the vertical axis

2b at their respective angles on the assumption that the vertical axis 2b is regarded as the

standard and that these angles are defined as 0° when the edge la and the edge lb overlap

with the vertical axis 2b. Incidentally, the gland packing as shown in Fig. 3 is a gland

packing as a referential art for explaining the characteristics of the present invention gland

packing.

In addition, the above inner-diameter-side acute angle portion and

outer-diameter-side acute angle portion, like the portion 3a' and the portion 4b' as shown

in Fig. 3 respectively, mean two angle portions having an acute angle among interior

angles of the above quadrilateral. The present invention gland packing is a gland packing,

in which these portion 3a' and portion 4b' are made flat portions as mentioned below.

As to the above flat portions, namely, the flat portions that the present invention

gland packing, has, it is enough that, for example, those portions are flat to such an extent

that the gland packing can substantially stably and certainly contact with a flat portion of

such as a neighboring gland packing or an adapter packing when the gland packing is

actually equipped to such as a sealing apparatus and then used. There is no especial limitation thereto. Therefore, the above flat portions don't need to be perfect plane

portions to overlap with a plane perpendicular to the central axis. The flat portions may

have a slight slope, or may have a portion partially having a curved surface, or may have

different cross sectional shapes depending upon the position of the cross section

(depending upon of which portion the cross section is observed). When the above flat

portions are shown as an optional cross sectional shape of the ring portion (an optional

cross sectional shape as cut by a plane including the central axis 2a), specifically, preferred

examples thereof include a shape such as the portion 3a and the portion 4b that are shown

in Figs. 2 (a) and (b). When the total width in the vertical axis 2b direction as to the ring

portion of the gland packing is regarded as t, the respective widths A and B of the flat

portions 3a and 4b in the direction of the vertical axis 2b are favorably A<0.5t and B<0.5t,

more favorably A<0.3t and B<0.3t. In the case where the above widths A and B are more

than 0.5 t, there is a possibility that the gland packing cannot efficiently be deformed in the

directions of the inner and outer diameters (so-called washer deformation of conical plate)

by a load applied from the central axis direction, resulting in lowering the sealability,

because the stress is not sufficiently caused in the directions of the inner and outer

diameters.

In the present invention gland packing, there is no especial limitation on the

range which the angles α and β as shown in Figs. 2 (a) and (b) can take. Specifically,

they are favorably 0°<α<90° and 0°<β<90°, more favorably 5°<α<40° and 0°<β<40°.

However, they may fitly be set in consideration of the length A of the above flat portion.

In general, if the widths A and B of the flat portions are wide, there are many cases where the angles α and β are set on the large side. Or otherwise if the widths A and B of the flat

portions are narrow, there are many cases where the angles α and β are set on the small

side. In addition, the angle α may be either equal to the angle β (α=β) or different from

the angle β (α≠β), and there is no especial limitation thereto. However, α=β is generally

favorable in respect to such as having wide use. Furthermore, the angle difference

between the angle α and the angle β is favorably 0<|α-β|<20°.

When the angles α and β are within the above ranges and further the angle

difference between the angle α and the angle β (|α-β|) is in the above-mentioned range, it

can be prevented that the clearances as formed between the gland packings are too large,

and that the deformation amount (strain amount) necessary for sufficiently displaying the

sealability is excessively large. At the same time, the malfunction of the equipability and

handling ability can be prevented wherein the cause of the malfunction is that the total

initial equipping length of the gland packings as equipped is too long.

There is no especial limitation on the cross sectional shape of the present

invention gland packing if the above flat portions 3a and 4b, and angle α and angle β

satisfy the above-mentioned conditions. Specifically, examples thereof include: (1) the

two edges at the inner and outer diameter sides have the same length, namely, α=β; (2) of

the two edges at the inner diameter side 1 c and the outer diameter side 1 d, the edge at the

outer diameter side Id is longer, namely, α>β (Fig. 2(a)); and (3) of the two edges at the

inner diameter side lc and the outer diameter side Id, the edge at the inner diameter side lc

is longer, namely, α<β (Fig. 2(b)).

In the cross sectional shape of the present invention gland packing, there is no especial limitation on its inner and outer diameters or the sizes of such as the

inner-diameter-side edge lc and the outer-diameter-side edge Id, and it is enough that they

are in such ranges as to hold as a ring packing in which the flat portions and the angles α

and β can satisfy the above conditions, particularly as a gland packing.

The present invention packing has the above-mentioned characteristic form.

Therefore, for example, in the case where the stem 5 in the stuffing box 6 is, as shown in

Fig. 5 (a) or Fig. 6 (a), equipped with the gland packings in such a manner that the gland

packings are alternately oriented and where they are thereafter, as shown in Fig. 5 (b) or

Fig. 6 (b), tightened by the packing holder 8, the gland packings are, like the change from

Fig.4 (a) to Fig. 4 (b), extended and deformed in the directions of the inner and outer

diameters as if an umbrella were spread (so-called washer deformation of conical plate

shape), so that the efficient and excellent sealability is displayed. In addition, the load

necessary for extending and deforming the present invention gland packing from Fig. 4 (a)

of the shape before tightening to Fig. 4 (b) of the shape after tightening is fairly decreased

in comparison with a gland packing having a rectangular cross section as conventionally

generally commonly used. Furthermore, the present invention gland packing also has no

problems such as permeation leakage of the packing itself as occurs to such as a

low-density gland packing, and can also display the sealability sufficiently.

In detail, when the pressure is applied to the present invention gland packing

from a portion giving the load (e.g. a tightening face 8a of the packing holder), the gland

packing is compressed in the thickness direction as a whole. As to the deformation of the

shape due to this compression, the presence of the aforementioned angle α and angle β is one factor for enabling easy deformation and extension in the directions of the inner and

outer diameters. Furthermore, because of the deformation and extension due to this

compression, in the gland packing as shown in Fig. 4 (b), the peak stress in the directions

of the inner and outer diameters is efficiently transmitted greatly particularly at the

following portions of: from the inner-diameter-side angle portion 3c to the stem side; and

from the outer-diameter-side angle portion 4c to the inner wall surface side of the stuffing

box, wherein the angle portion 4c has an opposite-angle relation to the angle portion 3c

concerning the cross sectional shape. In the present invention gland packing, this portion

which can efficiently transmit the stress is hereinafter referred to as a stress-concentrated

point for the sake of convenience.

As to the present invention gland packing, for example, in the case where the

present invention gland packing seals such as the stem or the inner wall surface of the

stuffing box, the sealability is displayed by the peak stress as caused at the

stress-concentrated point when the gland packing is extended and deformed in the

directions of the inner and outer diameters. Therefore, even if the total stress as

transmitted in the directions of the inner and outer diameters (for example, the total force

that holds the stem) is smaller than that in use of a conventional gland packing, the

lowering of the sealability is not observed. In short, even if the tightening face pressure is

smaller than conventional, the seal can be carried out sufficiently. Therefore, the axis

resistance as caused when the tightening and sealing are carried out is lowered as the

reflective effect. For example, when the gland packing is used for a seal portion of a

valve, the hand torque necessary for opening and shutting the valve can be lowered. Similarly, the deterioration of such as the stem and packing and the deterioration of the

gland packing itself due to friction when the tightening and sealing are carried out can be

lowered greatly. Therefore, it can be said that the gland packing is particularly favorable

to a seal portion of an equipment in which the axis movement is carried out so frequently

as to usually make such as the seal abrasion very large.

When the present invention gland packing displays not less efficient and not less

excellent sealability than conventional ones, even a tightening face pressure lower than

conventional is permitted. Therefore, for example, there is no especial limitation on such

as the packing holder 8. These neighboring machines can be prevented from enlarging

and weighting, and can be compacted, and besides the entire sealing apparatus can be

prevented from enlarging, and can be compacted.

In a specific use in which the high sealability is requested, it has hitherto been

determined that the use is met by a gland packing of which the size is strictly set for the

outer diameter of a stem and the inner measurements of a stuffing box (gland packing in

which: there little exists so-called tolerance, and there is little opening between the gland

packing and the stem, and between the gland packing and the inner wall surface of the

stuffing box). However, as mentioned above, the present invention gland packing has

efficient and soft deformability and extensibility in the directions of the inner and outer

diameters, and has the flat portions that can contact with each other certainly and stably.

Therefore, even if the measurements are not strictly set according to an object in a specific

use, the gland packing can meet the use. Furthermore, also in cases of usual use, a gland

packing having one set of measurements can meet wide conditions of measurements (measurements conditions of various objects) alone. Therefore, the setting of the size

kinds of the gland packings (kinds of product sizes) may be little, and the production

efficiency rises, and the production costs can be decreased. Specifically, when the

present invention gland packing is used for a sealing apparatus comprising such as a

stuffing box, the optimum deformation and extension amount to meet the individual

conditions of the various objects can be given to the aforementioned gland packing by

adjusting the tightening face pressure. Therefore, it can be used under wide conditions,

and simultaneously the high sealability can be achieved. In addition, when a

conventional gland packing is equipped to such as a stem in a stuffing box, it accompanies

difficulty of equipment in some extent (especially in cases of high-density-type sealing

apparatuses or in cases where the high sealability as mentioned above is requested, the

difficulty is larger, for example, because such as measurements are considerably strict).

However, when the present invention gland packing is used, the high sealability is ensured

due to the efficient deformability and extensibility in the directions of the inner and outer

diameters, therefore the measurements can afford to be set to make the equipment easier

than conventional products. Furthermore, even in cases where various changes in size

have occurred later, for example, in cases where the size of the gland packing has changed

from the original size due to such as friction and corrosion with the passage of time and in

cases where the size of the stem or inner wall surface of the stuffing box has changed from

the original size due to such as abrasion and corrosion (although there is no especial

limitation to these cases), suitable adjustment of the tightening face pressure makes it also

possible that the gland packing is extended and deformed efficiently and softly in the directions of the inner and outer diameters, thereby fitting the size again. Therefore, the

optimum sealability can be ensured again.

There is no especial limitation on the density (hardness) of the present invention

gland packing, but it may be fitly be adjusted to the optimum density according to the

sealability as requested and peripheral apparatuses. As mentioned above, the present

invention gland packing has efficient deformability and extensibility in the directions of

the inner and outer diameters. Therefore, for example, the good deformation and

extension in the directions of the inner and outer diameters can be carried out by a

tightening face pressure smaller than the tightening face pressure that has hitherto been

regarded as necessary when the density is increased higher than usual. Accordingly, the

use of the present invention gland packing can solve the demerits coming into question

about such as conventional gland packings that have higher density than usual, especially,

rectangular high-density gland packings wherein the above demerits are for example as

follows: the lack of transmitting the stress against the tightening face pressure due to lack

of softness (deformability and extensibility) in the directions of the inner and outer

diameters; the difficulty of the equipment; the enlargement of apparatuses in compliance

with such as dynamic request; and the increase of the axis resistance as caused by the

non-uniform deformation. By such reasons, when the present invention gland packing is

molded in high density, various excellent functions (e.g. shape stability, abrasion resistance,

anticorrosion, function of receiving a shaft such as a stem (function of preventing a moving

error or vibration of the shaft), and easiness of equipment) can be given to the present

invention gland packing, though the functions are not limited to these. There is no especial limitation on the structural shape and material quality of the

present invention gland packing, but specifically, preferred examples thereof include

knitted and plaited packings, laminated packings, metal packings, graphite packings, and

resin-molded packings.

The aforementioned knitted and plaited packings are generally packings as

obtained by knitting and plaiting either one yarn comprised of various fibrous materials

(e.g. carbon fibers and aramide fibers), or a thread obtained by twisting at least two yarns,

into desired shapes by such as braiding, braiding-over-braiding, square-braiding, and

interbraiding.

The aforementioned laminated packings are generally packings as obtained by: stamping

out a sheet material; and then processing the resultant material into a desired shape by

suitable methods such as cutting; and then press-molding the processed material with such

as a mold.

The aforementioned metal packings are mainly packings as obtained by

compression-molding such as metal foils.

Among these, the graphite packings and fluororesins are particularly favorable as the

material quality as used in the present invention gland packing, because they are excellent

in chemical resistance and self-lubricity.

The aforementioned graphite packings are generally packings of which the major

material is expanded graphite. Specifically, although not especially limited, preferred

examples thereof include tape-molding-type (curling-type) packings, tape-molding-type

packings containing wire mesh, tape-molding-type packings containing metal foil, braided-type packings, laminated-type packings, and compressed-molding-type packings.

The main raw material of the graphite packings is the expanded graphite, but supplement

materials (e.g. metal foils, metal wires, metal nonwoven fabrics, various fibrous materials,

liquid lubricants, and solid lubricants) can favorably be used further. These may be used

either alone respectively or in combinations with each other.

The fluororesin packings are packings of which the major raw material is a

fluororesin. Specifically, although not especially limited, preferred examples of the raw

material include PTFE (polytetrafluoroethylene), PFA (polytetrafluoroethylene

perfluoroalkyl ether copolymers), and FEP (copolymers of tetrafluoroethylene and

hexafluoropropylene), and they are, for example, molded by cutting-processing of

sleeve-shaped molded structures or by injection molding of raw pellets. The main raw

material is the fluororesin, but supplement materials (e.g. metal foils, metal wires, metal

nonwoven fabrics, various fibrous materials, and besides, liquid lubricants and solid

lubricants for coating or combining) can favorably be used further. These may be used

either alone respectively or in combinations with each other.

There is no especial limitation on the metals as the aforementioned supplement

materials, but preferred examples thereof include aluminum, lead, copper, stainless, Monel,

and Inconel. In addition, these may be used either alone respectively or in combinations

with each other. There is no especial limitation on the shapes when they are used, but

preferred examples thereof include foils, ribbons, particles, and cotton chips.

There is no especial limitation on the fibrous materials as the aforementioned

supplement materials, but preferred examples thereof include cotton, linen, nylon, PPS fibers, fluororesin fibers, fluororesin fibers containing graphite, carbon fibers, carbonized

fibers, graphitized fibers, metal fibers, glass fibers, aramide fibers, phenol fibers, ceramic

fibers, and asbestos. These may be used either alone respectively or in combinations with

each other.

There is no especial limitation on the liquid lubricants as the aforementioned

supplement materials, but preferred examples thereof include mineral oils, synthetic oils,

fats, synthetic fats, fluorinated oils, silicone oils, Vaseline, and various greases. These

may be used either alone respectively or in combinations with each other.

There is no especial limitation on the solid lubricants as the aforementioned

supplement materials, but preferred examples thereof include graphite, molybdenum

disulfide, tungsten disulfide, boron nitride, fluororesins, mica, talc, gold, silver, lead, and

various soft metals. These may be used either alone respectively or in combinations with

each other.

There is no especial limitation on alloys and blending resins, but preferred examples

thereof include nylon resins, PPS resins, acetal resins, phenol resins, epoxy resins, and

various rubbers. These may be used either alone respectively or in combinations with

each other.

In the case where the aforementioned expanded graphite is included as a material

when the present invention gland packing is molded, there can be obtained a gland packing

that is excellent in performances such as chemical resistance, movability, stress relaxability,

and particularly, stability in a wide temperature range, although there is no especial

limitation thereto. In addition, there is no especial limitation on a molding method for the present invention gland packing containing the aforementioned expanded graphite as a

material, but, specifically, preferred examples thereof include: 1) a tape-mold molding

method which involves curly rolling an expanded graphite tape, and thereafter

press-molding from the direction of a rolling axis; 2) a laminated-sheet molding method

which involves stamping out expanded graphite sheets into a desired shape with such as a

mold, and laminating and press-molding these resultant stamped-out sheets; 3) a molding

method which involves knitting and plaiting an expanded graphite yarn, and then

press-molding the resultant knitted and plaited material; and 4) a

three-dimensional-knitting-and-plaiting molding method which involves molding into a

desired shape with a three-dimensional-knitting-and-plaiting machine. Among these, the

1) tape-mold molding method and 2) laminated-sheet molding method are particularly

favorable.

In the case where the fluororesin such as PTFE or PFA is included as a material

that is excellent in performances such as chemical resistance, movability, and low dust

generation property, although there is no especial limitation thereto. In addition, there is

no especial limitation on a molding method for the present invention gland packing

containing the aforementioned fluororesin, but, specifically, preferred examples thereof

include: 1) in case of using the PTFE, a molding method which involves cutting-processing

sleeve-shaped molded products into a desired shape; and 2) in case of using the PFA, a

molding method which involves directly shaping raw pellets into a desired shape by such

as injection molding. In addition, as to the molding of the present invention gland packing, there is no

especial limitation on a preparing or processing method for making the aforementioned flat

portions, but it may be a preparing or processing method as usually used. Specifically,

examples thereof include methods that involve such as: changing the shape of the mold, as

used for molding, in such a manner that the aforementioned flat portions will be formed; or

once molding, and thereafter cutting-processing.

Preferred examples of the sealing apparatus comprising the present invention

gland packing include a sealing apparatus in which at least two of the aforementioned

present invention gland packings are equipped to the stem in stuffing box. In detail, for

example, as shown in Fig. 5 (a) or Fig. 6 (a), it is favorable that the stem 5 in the stuffing

box 6 is equipped with at least two of the above present invention gland packings 1 in such

a manner that they are piled in alternate orientation, and then the stem 5 and the inner wall

surface of the stuffing box 6 is sealed by tightening the packing holder 8. On this

occasion, the orientation of the shape of the equipped gland packings 1 is favorably such

that the slopes of the aforementioned other two edges (la and lb) are alternately oriented.

Incidentally, concerning how to alternately orient the slopes, there are, for example, a

pattern as shown in Fig. 5 (a) and a pattern as shown in Fig. 6 (a). In what orientation and

order the equipment is carried out can be changed according to the using object and use.

In addition, such as the number of the gland packings as equipped can be variously

changed. In addition, it is not limited to the alternating equipment of all the gland

packings, but the equipment can also be carried out in such a manner that a part of the

gland packings are piled in the same orientation and the others are piled in alternate orientation. Specifically, unless all the present invention gland packings are equipped in

the same slope orientation, the effects of the present invention can be displayed in any way

of equipment.

Of Fig. 5 (a) and Fig. 6 (a), either equipping method will do, but the form of Fig.

5 (a) is usually favorable in general. If the form of Fig. 5 (a) is selected, the contact area

between both end gland packings and the stem is in a state of being apart from the

pressurizing face of the packing holder and the inner bottom portion of the stuffing box

because of the clearance as formed between both end gland packings and the pressurizing

face and the inner bottom portion. Therefore, a so-called "protrusion (thrust)" as caused

by tightening after the equipment of the gland packings can be prevented, and the lowering

of the sealability can be prevented. The "protrusion (thrust)", for example, means that, in

Fig. 6 (a), a portion of the gland packing to which a load is applied gets into such as: a

slight opening of a portion where the stem 5 penetrates the inner bottom portion 7 of the

stuffing box; or a slight opening between the stem 5 and the packing holder 8. It causes

lowering the sealability of the apparatus.

In the sealing apparatus comprising the present invention gland packing, all the

structural factors (e.g. shape, measurements, and further, material quality) of the gland

packings 1 as used are favorably the same as those of each other gland packing in

consideration of convenience and uniform sealability regardless of each seal portion.

However, there is no especial limitation thereto. Various gland packings, of which such

as the width of the above flat portions, the respective sizes of the above angle α and angle

β, and the shape or measurements of other portions, and further the material quality are different, may be used in any combination with each other. Incidentally, as is shown in

Fig. 7 and Fig. 8, the inner bottom portion 7 side and/or the packing holder 8 side in the

stuffing box may be equipped with adapter packings 10. In addition, as is shown in Fig. 9,

at least one of the present invention gland packings may be used together with at least two

of conventional -type gland packings 10a of which the cross sectional shapes are

rectangular. In addition, as is shown in Fig. 10 and Fig. 11, the present invention gland

packings may be used together with conventional-type gland packings 10b of which the

cross sectional shapes are rectangular in such a manner that the conventional-type gland

packings are allowed to intervene between the present invention gland packings.

Furthermore, as is shown in Fig. 12, members other than the gland packing may be used

together. For example, hard rings 10b comprised of such as metals or resins are used with

them allowed to intervene, whereby the extent of tightening the entire sealing apparatus or

the balance between the sealability and the low torque can be adjusted according to the

using object and use. In this way, also when such as the adapter packings 10, the above

conventional-type gland packings 10a, or the hard rings 10b are used together, all the

structural factors (e.g. shape, measurements, and further, material quality) of the present

invention gland packings 1 are favorably the same as those of each other gland packing.

However, there is no especial limitation thereto, and the various gland packings as

mentioned above may be used in any combination with each other. If only gland

packings of a kind are used when such as a stem is sealed, there have hitherto been many

cases such as "requisite performances or items that cannot be satisfied" and "deficient

performances that cannot be compensated". Therefore, for example, at least two kinds of gland packings having different shapes, densities, and material qualities have been selected,

combined, and used. There is no especial limitation on the above requisite performances

and deficient performances, but, specifically, preferred examples thereof include

performance of uniform tightening distribution (sealability), heat resistance, pressure

resistance, and frictional resistance.

When a gland packing having a high-density character is, for example, selected

as the present invention gland packing, the efficient extensibility and deformability that the

present invention gland packing has can also be displayed in addition to the high-density

character. Therefore, the gland packing can be made to have at least both the characters

of the low density and high density as have hitherto been thought. Also in the structure of

the present invention sealing apparatus, it is favorable in view of simplification.

As is mentioned above, the present invention gland packing has the efficient

extensibility and deformability. Therefore, when at least two of the gland packings are

used for the sealing apparatus, the individual gland packings have stress-concentrated

points at the inner diameter side and outer diameter side, and the stress can efficiently be

caused even if only one kind of gland packing is used. Moreover, when the gland

packing is allowed to contact with its neighboring gland packings at the flat portions, the

stress concentration is raised at the contact portions due to synergistic effect both at the

inner diameter side and outer diameter side. Therefore, in the sealing apparatus

comprising the present invention gland packing, gland packings of a kind are favorably

used also from the viewpoint of simplifying the structure.

In the sealing apparatus comprising the present invention gland packing, as is shown in Fig. 5 (a) and Fig. 6 (a), a definite space can be provided between the gland

packings 1 as equipped to the stem 5 before the packing holder 8 is tightened. The

aforementioned space is derived from that: in the cross sectional shape of the gland

packing 1, the aforementioned other two edges (la and lb) have their respective slopes of

the same orientation as to a vertical axis perpendicular to a central axis; and the at least two

gland packings are equipped in such a manner that the orientations of the above slopes will

be alternate. For the purpose that the gland packings 1 as equipped to the stem 5 in the

stuffing box 6 can, as mentioned above, display the efficient extensibility and

deformability in the directions of the inner and outer diameters, it is favorable that such

spatial room is provided.

In the sealing apparatus comprising the present invention gland packing, when

the tightening face pressure is applied by the packing holder, then, as is shown in Fig. 5 (b)

and Fig. 6 (b), the gland packings 1 utilize the space between them to become extended

and deformed while decreasing this space. Then, the stress is efficiently and

concentratedly transmitted from the mutually contacting portions of the gland packings,

and the stem 5 and the inner wall surface of the stuffing box 6 are sealed. In this case, the

tightening face pressure as applied by the packing holder is efficiently transmitted to the

gland packings 1. Therefore, all the gland packings 1 have stress-concentrated points,

especially in the above contacting portions. Especially, as is shown in Fig. 5 (a) and Fig.

6 (a), when all the present invention gland packings are, as mentioned above, equipped in

alternate orientation, the sealing effect as a whole is a multistagewise sealing effect, and

the extremely excellent sealability is displayed. In addition, in Fig. 5 (a) and Fig. 6 (a), all the present invention gland packings are equipped in alternate orientation. Therefore,

the above contacting portions, namely, the portions where the flat portions of the present

invention gland packings contact with each other, are extremely excellent

stress-concentrated points at both sides of the inner diameter side and outer diameter side,

and besides, the high sealability having substantially the same level can be displayed at any

stress-concentrated point in the stuffing box almost without depending upon the distance

from the packing holder 8. Usually, when conventional-type gland packings (e.g. gland

packings of which the cross sectional shape is rectangular or quadrangular) were used, it

was inevitable that the sealability is lowered as the distance from the packing holder 8

becomes farther. Therefore, as functions and effects of the present invention, this can be

said to be one of particularly excellent effects together with the stress concentration of the

above contacting portions.

As is shown in Figs. 7 to 12, as mentioned above, preferred examples of the

sealing apparatus comprising the present invention gland packing further include: a sealing

structure in which adapter packings are equipped at the inner bottom portion 7 side and/or

the packing holder 8 side in the stuffing box; and a sealing structure including a

combination of the present invention gland packing and the conventional-type gland

packing of which the cross sectional shape is rectangular.

Specifically, the adapter packing 10 and hard ring 10b favorably have high

strength and high elasticity, and they are favorably made of metals or resins. The adapter

packing 10 may be replaced with such as a conventional gland packing of which the cross

sectional shape of a ring portion is rectangular, and packings having various material qualities may fitly be selected. In addition, when the adapter packing 10 is used at the

inner bottom portion 7 side and/or the packing holder 8 side in the stuffing box is favorable

in that effects (e.g. preventing protrusion (thrust) of the gland packing) can be obtained.

In addition, in the sealing apparatus comprising the present invention gland

packing, a gland packing of which the shape is different from that of the present invention

gland packing may fitly be used in combination therewith. Examples of the gland

packing having such a different shape include the above-mentioned rectangular gland

packings, but there is no especial limitation thereto. In addition, when only the present

invention gland packings are used as gland packings in the sealing apparatus comprising

the present invention gland packing, at least unless all the present invention gland packings

are equipped in such a manner that they are piled in the same orientation, then the effects

of the present invention can be displayed

In the sealing apparatus comprising the present invention gland packing,

preferred examples of its form include a form in which the equipped gland packings are

such that the present invention gland packings and the rectangular gland packings are

alternately equipped in order. The most favorable examples thereof include a form of the

alternating equipment such that the equipped gland packings are as shown in Fig. 5 (a) or

Fig. 6 (a), namely, a form in which all the equipped gland packings are equipped in such a

manner that the orientations of the slopes of the other two edges of each gland packing are

different from those of its neighboring gland packing.

The sealing apparatus comprising the present invention gland packing can be

used for what has a sealing portion structure of any type such as so-called standard type or lantern-ring type, although there is no especial limitation thereto. Furthermore, although

not especially limited, specifically utilizable examples favorably include: pumps, such as

rotary pumps and reciprocating pumps; valves, such as gate valves and glove valves; and

various stirring machines.

While retaining the above-mentioned characters, the present invention gland

packing 1 can favorably be provided with various structural changes (changes in shape) as

shown below, and can be used for the present invention sealing apparatus. In addition,

the sealing apparatus can also favorably be provided with various structural changes

(changes in shape). In these, there are also included those which come to have more

excellent characters due to the structural changes.

There is no especial limitation on the above structural changes, but, as to the

aforementioned gland packing 1, preferred examples include those which are provided

with arch-shaped (arc-shaped) portions as shown in Fig. 13 (a) and (b) when taking note of

the edges la and lb that cross the axis 2b, perpendicular to the central axis 2a, at angles in

the same direction in the cross sectional shape of the gland packing 1 as shown in Fig. 2 (a).

Similarly, as to the aforementioned sealing apparatus (e.g. stuffing box or packing holder),

examples include those in which a slope is provided to the inner bottom portion 7 of the

stuffing box or to a pressurizing face 8a of the packing holder. As to these structural

changes, all the above portions that are taken note of may be either changed or not, and

they may fitly be combined. In addition, the above structural changes may be applied

either alone respectively or in combinations with each other. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, the present invention is more specifically illustrated by the following

examples of some preferred embodiments. However, the present invention is not limited

to these examples. Incidentally, hereinafter, the unit "part(s) by weight" may simply be

referred to as "part(s)" for the sake of convenience.

-Example 1-

As a major raw material, an expanded graphite tape was prepared by slitting an

expanded graphite sheet into strips having a width of 15 mm, and this tape was curly rolled.

Thereafter, the resultant rolled material was compression-molded with a mold, thus

obtaining a graphite gland packing of Example 1 (packing inner diameter: 20 mm, packing

outer diameter: 33 mm, outer-diameter-side thickness: 6.5 mm, angles α and β as shown in

Fig. 2 (a) or (b): 5° and 5° respectively, width A: 0.15t, width B: 0.15t, and density: 1.70

g/cm ) (hereinafter, referred to as a gland packing (1)). Herein, the above

"outer-diameter-side thickness" means the length of the edge Id as shown in Fig. 2 (a) or

(b).

Four rings of these gland packings (1) were equipped to a sealing apparatus as

shown in Fig. 16 (hereinafter, referred to as a sealability-testing apparatus), and then the

sealability was evaluated.

The sealability-testing apparatus comprises: an upper receptacle having such as a

stem (driving shaft) 15, a stuffing box 6, and a packing holder 8; and a lower receptacle

that is incorporated with this upper receptacle by tightening bolts 12 through an O-ring 11.

The lower receptacle is provided with the following: a pressurizing opening 13 in order to inject nitrogen gas; a gas-enclosing portion 16; and bearings 14 and thrust bearings 17 in

order to rotate the stem (driving shaft) 15. The gland packings (4 rings) as used for the

sealability test are equipped between the inner bottom portion 7 side of the stuffing box

and the pressurizing face 8a of the packing holder. Then, the inner wall surface of the

stuffing box 6 and the surface of the stem (driving shaft) 15 are sealed by tightening the

packing holder 8. Incidentally, the gland packings (1) were equipped in a pattern having

the orientation as shown in Fig. 5 (a) and Fig. 16.

When the sealability test is carried out, nitrogen gas was used as a fluid that was

sealed in the gas-enclosing portion 16 in the sealability-testing apparatus, and that was an

object of sealing. The nitrogen gas is injected from the pressurizing opening 13 into the

gas-enclosing portion 16 so that the gas pressure will be constantly 10 MPa. While this

gas pressure is maintained, the entire sealability-testing apparatus was immersed into water.

The tightening face pressure of the packing holder 8 was stepwise increased 5MPa by

5MPa from 0 MPa to 45 MPa, and the sealability was tested every step in turn. The

judgment of whether the sealability was achieved or not was made on the basis of the

leaking rate of the nitrogen gas in water. When this value was less than 5.0 ^χ 10^"5 Pa πrVs

was regarded as when the sealing was achieved. The "tightening face pressure" under

which the sealing of nitrogen gas was achieved in this way was recorded to measure the

"strain ratio" and "axis resistance per contact area". The results are shown in Table 1.

Incidentally, the leakage of the nitrogen gas was not observed at all except in the stuffing

box 6. As to the measurement of the aforementioned leaking rate, the leaked nitrogen gas

is recovered by replacement above the water (about 3 minutes), and the leaking rate is calculated from the recovered volume and the recovering time.

In addition, the measurement methods of the tightening face pressure, strain ratio,

and axis resistance per contact area are shown below.

Tightening face pressure (MPa):

This is a tightening load per projective (unit) area of the gland packing as viewed

in the direction of the central axis when the aforementioned sealing of nitrogen gas is

achieved.

Strain ratio (%):

This is a ratio at which the equipping length of the gland packings in the

direction of the axis (length of from the pressurizing face of the packing holder to the inner

bottom portion of the stuffing box) decreases from before tightening till the

aforementioned sealing of nitrogen gas is achieved after tightening. Specifically, when

the equipping lengths of the gland packings in the direction of the axis before and after the

tightening are regarded as L and 1 respectively, then the strain ratio (%) can be calculated

from the following equation: "strain ratio (%) = (L - 1)/L ^χ 100".

Axis resistance per contact area (N/mm²):

This is a value obtained in the following way: the axis resistance (namely, force

(load) necessary for rotating the axis) under which the aforementioned sealing of nitrogen

gas is achieved is measured by a torque wrench, and the resultant measured value is

divided by the apparent contact area that is obtained by multiplying the equipping length 1

after the tightening of the gland packing by the axis circumference.

-Examples 2 to 4- Graphite gland packings of Examples 2 to 4 (hereinafter, referred to as gland

packings (2) to (4)) were obtained by repeating the same procedures as of Example 1

except that the angles α and β and the widths A and B, as adjusted in Example 1, were

changed as shown in Table 1. In addition, the same evaluations of the sealability as of

Example 1 were carried out. The results are shown in Table 1.

-Comparative Example 1-

A graphite gland packing of Comparative Example 1 (of which the cross

sectional shape is rectangular) (hereinafter, referred to as comparative gland packing (1))

was obtained by repeating the same procedure as of Example 1 except that the angle α, the

angle β, and the outer-diameter-side thickness (similarly, also inner-diameter-side

thickness) were changed to 0°, 0°, and 6.5 mm respectively. In addition, the same

evaluation of the sealability as of Example 1 was carried out. The results are shown in

Table 1.

[Table 1]

From the results as shown in Table 1 , it is understood that: in any of cases where the present invention gland packings of Examples 1 to 4 are used, gas can be sealed under

a lower tightening face pressure than that of the conventional rectangular gland packing of

Comparative Example 1. Therefore, the present invention gland packings of Examples 1

to 4 can be applied safely and can display sufficient sealability, even in a portion to which

a very high load cannot be applied. In this way, even if the tightening face pressure is

low, the present invention gland packing can achieve sufficient sealing, and it is

understood that the axis resistance can also be lowered as a result accompanying this.

Accordingly, when the present invention glad packing is applied to such as a valve, the

hand torque necessary for opening or shutting it is greatly decreased. Above all, it is

favorable to usually use the present invention gland packing for portions where the axis is

said to usually be moved so frequently that apparatuses and gland packings are remarkably

deteriorated by seal abrasion. Similarly, because a low tightening face pressure is enough,

it can be said that: the equipment and tightening are easily carried out, and no large power

is necessary even for retaining the tightened state, and the handling property is very

excellent. In addition, the compactness of the entire sealing apparatus can also be

achieved.

In this way, the following simulation was carried out in order to directly explain,

from an aspect of the functional mechanism, that such as the sealability of the present

invention gland packing is remarkably superior to that of the conventional gland packing

(of which the cross sectional shape is rectangular).

That is to say, modeled as to the gland packing (3) and the comparative gland packing (1) were sealing apparatuses comprising 4 rings in total each of both gland

packings in the form as shown in Fig. 5 (a), and the transmitted face pressures (MPa) to the

inner-diameter-side and outer-diameter-side seal faces were determined by the following

detailed simulations. Herein, simulated as to the gland packing (3) was a case where

sealing was carried out under a tightening face pressure of 20 MPa, and simulated as to the

comparative gland packing (1) were cases where sealing was carried out under tightening

face pressures of 20 MPa and 45 MPa respectively.

When the above simulations were carried out, the transmitted face pressures to the

inner-diameter-side and outer-diameter-side seal faces were determined by finite-element

analysis (FEA) in a state where the gland packings ware equipped to the sealing apparatus

and tightened, wherein the transmitted face pressures were caused by the tightening face

pressure. The method of axis-symmetrical elasticity calculation was applied to the

finite-element analysis (FEA), and then portions other than the gland packing (e.g. the axis,

stuffing box, and packing holder) were made of rigid bodies. There were a coefficient of

friction, Young's modulus, Poisson's ratio, density, and number of elements as material

constants of the gland packing. These values were set by making reference to such as a

strain ratio, righting ratio, and change of measurements per one ring of the gland packing,

and values in literature. Specifically, the coefficient of friction, Young's modulus,

Poisson's ratio, and density were set at 0.3, 117.68 MPa, 0.3, and 1.70 g/cm³ respectively.

The number of elements was set at 400 relative to the entire gland packings (4 rings) as

equipped.

Next, the "length distance" from the pressurizing face of the packing holder to the inner bottom portion of the stuffing box when the packing holder was tightened was

regarded as "1", and then graphs were prepared as shown in Figs. 14 and 15, in which the

X axis is a length distance from the pressurizing face of the packing holder, and in which

the Y axis is a "transmitted face pressure (MPa)" corresponding to this length distance.

Incidentally, the transmitted face pressure from the outer diameter side of the gland

packing to the inner wall surface of the stuffing box is shown in Fig. 14, and the

transmitted face pressure from the inner diameter side to the axis (stem) surface is shown

in Fig. 15.

From the results as shown in Figs. 14 and 15, the following is understood.

Specifically, the present invention gland packing has a stress-concentrated point where the

tightening face pressure is high efficiently transmitted to both seal faces that are located at

the inner and outer diameter sides. Therefore, when this gland packing is used for a

sealing apparatus, there exist, for a definite tightening face pressure, at least two acutely

peaking seal portions (seal portions having a large transmitted face pressure) which are

superior when compared with cases where conventional-type gland packings (of which the

cross sectional shapes are rectangular) are used. In addition, the peak sizes are on nearly

the same level in any comparison of between the inner-diameter-side peaks, between the

outer-diameter-side peaks, and between the inner-diameter-side peak and the

outer-diameter-side peak, and stable peak values are shown irrespective of the distance

from the tightening face or whether at the inner diameter side or at the outer diameter side.

Accordingly, the efficient and multistagewise sealing synergistic effect can be displayed,

and therefrom it is found that there is brought not only the excellent sealability as displayed at each peak portion, but also as a whole, sealing effects which are much more

efficient and excellent than conventional.

INDUSTRIAL APPLICATION

The present invention can provide a novel gland packing and a sealing apparatus

comprising this, wherein the gland packing displays high and stable sealability for a stem

and an inner wall surface of a stuffing box even for uses further requesting the movability

(rotation and reciprocating movement), and further, gives excellent effects, such as

decrease of moving resistance of a stem, shape stability, adaptability to a corroded and

worn-out stem and stuffing box, function for receiving shafts, easiness of equipment,

simplification of sealing structure, and compactness of a sealing apparatus.

Claims

1. A gland packing, which is a ring packing of which the cross sectional

shape is a quadrilateral, wherein both two edges at inner and outer diameter sides of the

quadrilateral are parallel to a central axis of the gland packing, and wherein the other two

edges have slopes of the same orientation as to an axis perpendicular to the central axis,

with the gland packing being characterized in that an inner-diameter-side acute

flat portions.

2. A sealing apparatus, which is equipped with gland packings that are

piled in a stuffing box, and which seals the stuffing box,

with the sealing apparatus being characterized in that:

at least one of the gland packings as equipped in the stuffing box is equipped

therein in such a manner that the orientations of the slopes of the other two edges of the at

3. A sealing apparatus according to claim 2, wherein all the gland

packings as equipped in the stuffing box are equipped therein in such a manner that the

orientations of the slopes of the other two edges of each gland packing are different from

those of its neighboring gland packing.

4. A sealing apparatus according to claim 2 or 3, which is further

equipped with an adapter packing at an inner bottom portion side and/or a packing holder

side in the stuffing box.