JPS5843634B2 - butterfly valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) [Object of the Invention] The present invention relates to a fluororesin coating for protecting the seat ring and valve body of a linear valve.

(b) [Field of application of the present invention] This invention is applicable to fluids that corrode the surfaces of rubber seat rings and plastic and metal valve bodies, particularly halogen gases (hereinafter referred to as "corrosive gases") such as chlorine gas and bromine gas. That's what it means.

) is used to protect the seat ring and valve body of linear valves used in transportation piping.

(c) [Prior art and its problems] Generally, a rubber seat ring with high sealing properties is used as a seat ring for a linear valve, but this rubber seat ring has poor wear resistance and slipperiness. , easy to deform.

This rubber seat ring (hereinafter referred to as "seat ring").

) The surface of the seat ring is made of polytetrafluoroethylene resin (hereinafter referred to as "PTFE") in order to ensure the abrasion resistance and lubricity of the sealing surface without impairing the sealing properties of the seat ring, and to prevent deformation as much as possible.

) is known to be coated with
-25705).

This thing has annular ears 3c protruding from the left and right flange parts 3b of an annular rubber seat ring 3 (see Fig. 1).
The side surfaces of the main bodies 1 and 2 are held between the flange portions 3b, and the ears 3c of the flange portions are engaged with the annular grooves 1a (2a) provided on the side surfaces of the main bodies 1.2 to remove the seat ring. The inner circumferential surface of the sea 1-IJ song and both flanges are covered with a coating layer 5 of PTFE.

Therefore, the sealing surface on the outer periphery of the valve body 6 slides on and comes into contact with the coating layer 5 of the seat ring.

This PTFE coating layer is an excellent layer that covers the shortcomings of the seat ring when used for normal fluids and compensates for strong mechanical deterioration.
When used in linear valves used in transportation piping for corrosive gases such as chlorine gas, especially these high-temperature gases, PTFE
Because of the large change in permeation of the halogen gas, there is a problem in that the C1-IJ song is corroded by the gas and its durability is significantly impaired.

This is because corrosive gas such as chlorine gas permeates through the PTFE coating layer itself, and gradually
Invading the inner peripheral surface of the song and damaging it, Sea 1-I
The elasticity of the J-song is lost, which eventually leads to a decline in pressure resistance and sealing performance.Also, the surface of the valve body is also attacked by corrosive gas, so the contact surface (sealing surface) with the seat ring on the outer periphery of the valve body must be smooth. This is because the slipperiness between the seat ring and the valve body is lost, and the sealing surface of the seat ring is damaged.

[Technical Problem of the Present Invention] The technical problem of the present invention is to prevent corrosive gas from penetrating into the sea 1-IJ song portion and to prevent corrosion of the valve body by the gas. To ensure lubricity between the sealing surface of a seat ring and the sealing surface of a valve body for a long period of time without impairing the elasticity, sealing performance and wear resistance of the valve body.

(e) [Technical means and their effects] The technical means taken to solve the above technical problem are as follows: (1) The outer peripheral surface of the seat ring is provided with (2) A coating layer (hereinafter referred to as "
PVDF coating layer.

) to cover the inner circumferential surface of the sea 1-IJ song.
) At least the outer peripheral portion of the valve body is coated with a PVDF coating layer.

This technical means works as follows.

In other words, the PVDF coating layer itself has excellent blocking properties against the permeation of corrosive gases such as chlorine gas, so even if the gas permeates through the PTFE coating layer of the seat ring, the penetration is blocked by the PVDF coating layer inside the PTFE coating layer. Since the outer periphery of the valve body is protected by the PVDF coating layer, the outer periphery of the valve body that comes into contact with the sealing surface of the seat ring does not reach the rubber seat ring. Not attacked by corrosive gases.

In addition, a PVDF coating layer is applied to the sheet link.
By coating with TFE coating layer, PVD
Since F has poor elasticity, it will impede the elasticity of the sealing surface of one seat ring. Since the annular groove of the book is formed, the sea 1
- The vicinity of the sealing surface of the IJ song body tends to deform in the radial direction.

Therefore, the deterioration of the elasticity of the sealing surface of the seatring due to coating the seatlink with the PVDF coating layer can be compensated for, and overall, the sealing surface of the seatring has the same elasticity as the conventional one. can be secured.

Furthermore, since the sliding contact between the valve body and the seat ring is made through the highly slippery PTFE coating layer coated on the seat ring and the PVDF coating layer on the valve body, the sealing surfaces of the seat ring and the valve body are durable. Regarding abrasion and slipperiness, tubules are not inhibited.

(to) [Special effects of the present invention] See! - In order to prevent the permeation of corrosive gases into the inside of the IJ song valve body sealing surface and to ensure wear resistance and lubricity between both sealing surfaces, both seat surfaces are coated with PVDF. Since it is only necessary to further coat either one of the two coating layers with a PTFE coating layer, the above-mentioned problems of the present invention can also be solved by double coating the outer circumference of the valve body with PVDF and PTFE. be able to.

However, in this case, since J'VDF has high permeability to high temperature moisture (moisture permeability 230
” cc-cyri, /cyi, 5eC-CrIIH,
F (moisture at 40°C)), the moisture in the hot corrosive gas passes through the PVDF coating layer and reaches the inner peripheral surface of the rubber seat ring.

In this state, if the shearing force associated with opening and closing the valve body is repeatedly applied, the seal of the seat ring will be greatly distorted in the shearing direction, causing the PVDF coating layer and the abutting surface of the seat ring to separate, resulting in peeling. Moisture that permeates into the space between the PVDF coating layer and the seat ring accumulates, further promoting this peeling, pushing up the PVDF coating layer, and causing friction with the valve body when the valve body opens and closes, causing the PVDF coating layer to A problem arises in that it becomes damaged and becomes unusable.

On the other hand, in the present invention, C) IJ song P
The VDF coating layer is made of PTFE (moisture permeable 36XLO-10cc-c), which has extremely low permeability to high temperature moisture.
m7'cyt -5ec-c/7T, Hg (moisture at 40°C)) coating layer, so moisture in the high temperature gas as described above is suppressed as much as possible from entering the PVDF coating layer. Therefore, peeling between the rubber sheet ring and the PVDF coating layer can be prevented.

In addition, regarding the valve body, even if the moisture of the gas passes through the PVDF coating layer, the shear stress generated in the adhesive layer between the PVDF coating layer and the surface of the valve body is small, and the strain in the shear direction of the valve body is small. Since the PVDF coating layer is small, there is no problem of peeling between the valve body and the PVDF coating layer due to the high temperature moisture permeability of the PVDF coating layer.

Unlike the case of coating a seat ring, the PVDF coating on the valve body allows the coating layer to be thicker, so that the permeation of high temperature moisture of the high temperature corrosive gas can be suppressed as much as possible.

(g) [Example] Hereinafter, an example showing a specific example of the above-mentioned technical means will be described.

(See Figures 2 and 3) The main body consists of two parts 1°2 connected by bolts 8, the center of which is a cylindrical flow channel.

A seat ring 3 having a coating layer is fitted onto the inner peripheral surface and both side surfaces of the main bodies 1 and 2.

3 is a rubber seat ring having a coating layer made of natural rubber or synthetic rubber (such as chloroprene rubber or silicone rubber); , by fitting the annular ears 3C provided at the ends of the flange portions into the annular grooves 1a (2a) provided on both sides of the main bodies 1, 2, the inner peripheral surfaces and both sides of the main bodies 1, 2 Covers the surface.

On the outer circumferential surface of the seat ring 3, avoiding the position facing the sealing surface 7 with the valve body 6, there are 1
The annular groove 3a of the book is provided.

This annular groove 3a serves as a relief for the deformation of the seat ring 3 due to rotation of the valve body 6, etc., and also compensates for the deformability of the seat ring 3 in the portion sandwiched by the annular groove 3a, helping to make a close contact with the valve body 6. Its function is to obtain a sufficient sealing effect with a small contact pressure.

It is preferable that the annular groove 3a be provided at a midpoint between a position on the outer circumferential surface of the seat ring 3 facing the center line of the sealing surface 7 and a distance in the flow path direction from the inner side surface of the flange portion 3b.
The width of the groove is preferably greater than or equal to the minimum width of the sealing surface of the valve body 6, and the depth of the groove is 1/3 to 1/3 of the thickness of the seat ring 3 main body. It is preferable to make it honey by about 4 degrees.

The inner peripheral surface and both side flange portions 3b of the seat ring 3 are coated with a PTFE coating layer 5 via a PVDF coating layer 4.

The thickness of the PVDF coating layer 4 is 0.9-1.5m1
It is best to set the value to vary as much as rL.If the layer thickness becomes too large, the permeation of moisture in the high-temperature corrosive gas will be somewhat suppressed, but since PVDF has poor elasticity, the elasticity of the seat ring 3 will be destroyed. As a result, a problem arises in that excellent pressure resistance and sealing performance cannot be obtained.

Moreover, the thickness of the PTFE coating layer 5 is 1.0 to 3.
．． It is best to set it to 0m Chikuhohen.

PTFE is more elastic than PVDF, so PVDF
Even if the coating layer is thicker than DF, the elasticity of the seat ring 3 will not be lost, but it is preferably 1.0 to 1.
It is best to set it up when it is about 5 hours cold.

Formation of the coating layer on the sheet ring 3 using PVDF is performed by applying an adhesive between the preformed sheet ring and the PVDF coating layer easily obtained by powder firing, and bonding by vulcanization. .

Furthermore, the method for forming the PTFE coating layer 5 on the PVDF coating layer 4 is generally to adhere the two coating layers using an existing effective adhesive.

Reference numeral 6 denotes a valve body, which functions to open and close the flow path by rotating the spindle with which it is engaged.

The outer circumference of the valve body 6 (at least 2 times the diameter of the valve body from the outer circumference of the valve body)
0%) is the PVDF coating layer 4
covered with.

The thickness of the coating layer may be set to about 1.0 to 3.0 mm, or more depending on the case, but preferably,
It is preferable to set it between 1.0 and 2.0.

Although it is sufficient to provide the PVDF coating layer at least on the outer periphery of the valve body 6, it is somewhat costly due to the ease of coating, problems in processing the valve body, protection of the valve body, etc. However, it is better to coat the entire surface of the valve body 6 with PVDF.

The formation of the PVDF coating layer 41 on the valve body 6 is generally performed by injection molding (insert molding), wiping, or the like.

[Brief explanation of drawings]

1 is a cross-sectional view of an example of a conventional butterfly valve, and FIG. 2 is a central longitudinal sectional view of an embodiment of the present invention, with a partial front view remaining;
FIG. 3 is a cross-sectional view of FIG. 2. In the figure, 1.2 two bodies, 3: seat ring, 3a:
Annular groove, 3b: flange portion, 3C: annular ear, 4:
PVDF coating layer, 5: PTFE coating layer, 6: valve body, 1: sealing surface, 8: bolt.

Claims (1)

[Claims] 1. In a linear valve having a rubber seat ring whose inner circumferential surface is covered with a PTFE coating layer, on both sides of the seat ring's outer circumferential surface at a position opposite to the annular contact surface with the valve body. an annular groove is formed in each of the valve bodies, the inner peripheral surface of the seat ring is covered with the PTFE coating layer via the PVDF coating layer, and at least the outer peripheral part of the valve body is covered with the PVDF coating layer. linear valve.